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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Apr. 01, 2017	Apr. 18, 2017
Document and Entity Information
Entity Registrant Name	SILICON LABORATORIES INC
Entity Central Index Key	0001038074
Document Type	10-Q
Document Period End Date	Apr. 01, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-30
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		42,358,718
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q1

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Apr. 01, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 225,399	$ 141,106
Short-term investments	396,327	153,961
Accounts receivable, net	75,852	74,401
Inventories	61,308	59,578
Prepaid expenses and other current assets	54,360	61,805
Total current assets	813,246	490,851
Long-term investments	5,257	5,196
Property and equipment, net	130,635	129,559
Goodwill	288,629	276,130
Other intangible assets, net	103,638	103,565
Other assets, net	58,021	76,543
Total assets	1,399,426	1,081,844
Current liabilities:
Accounts payable	43,781	39,577
Accrued expenses	47,416	50,100
Deferred income on shipments to distributors	49,700	45,568
Income taxes	4,396	4,450
Total current liabilities	145,293	139,695
Long-term debt		72,500
Convertible debt	332,502
Other non-current liabilities	42,797	42,691
Total liabilities	520,592	254,886
Commitments and contingencies
Stockholders' equity:
Preferred stock-$0.0001 par value; 10,000 shares authorized; no shares issued and outstanding
Common stock - $0.0001 par value; 250,000 shares authorized; 42,348 and 41,889 shares issued and outstanding at April 1,2017 and Deceber 31, 2016, respectively	4	4
Additional paid-in capital	59,714	24,463
Retained earnings	819,641	801,999
Accumulated other comprehensive income (loss)	(525)	492
Total stockholders' equity	878,834	826,958
Total liabilities and stockholders' equity	$ 1,399,426	$ 1,081,844

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Apr. 01, 2017	Dec. 31, 2016
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	250,000	250,000
Common stock, shares issued	42,348	41,889
Common stock, shares outstanding	42,348	41,889

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Condensed Consolidated Statements of Income
Revenues	$ 179,028	$ 162,025
Cost of revenues	73,867	66,494
Gross margin	105,161	95,531
Operating expenses:
Research and development	52,324	49,046
Selling, general and administrative	40,155	39,637
Operating expenses	92,479	88,683
Operating income	12,682	6,848
Other income (expense):
Interest income	696	271
Interest expense	198	(655)
Other, net	(120)	(391)
Income before income taxes	13,456	6,073
Provision (benefit) for income taxes	(1,970)	265
Net income	$ 15,426	$ 5,808
Earnings per share:
Basic (in dollars per share)	$ 0.37	$ 0.14
Diluted (in dollars per share)	$ 0.36	$ 0.14
Weighted-average common shares outstanding:
Basic (in shares)	42,096	41,629
Diluted (in shares)	43,030	42,199

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 15,426	$ 5,808
Net changes to available-for-sale securities:
Unrealized gain (losses) arising during the period	245	(251)
Net changes to cash flow hedges:
Unrealized losses arising during the period		(286)
Reclassification for (gains) losses included in net income	(1,808)	66
Other comprehensive loss, before tax	(1,563)	(471)
Benefit from income taxes	(546)	(165)
Other comprehensive loss	(1,017)	(306)
Comprehensive income	$ 14,409	$ 5,502

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Operating Activities
Net income	$ 15,426	$ 5,808
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation of property and equipment	3,596	3,310
Amortization of other intangible assets and other assets	6,752	7,980
Amortization of debt discount and debt issuance costs	869
Stock-based compensation expense	10,486	10,344
Income tax benefit (shortfall) from stock-based awards		(1,025)
Excess income tax benefit from stock-based awards		(6)
Deferred income taxes	(4,059)	(38)
Changes in operating assets and liabilities:
Accounts receivable	(1,252)	(990)
Inventories	(1,636)	4,580
Prepaid expenses and other assets	6,708	9,159
Accounts payable	5,565	1,559
Accrued expenses	(3,889)	6,260
Deferred income on shipments to distributors	4,038	5,558
Income taxes	945	494
Other non-current liabilities	(1,536)	(10,584)
Net cash provided by operating activities	42,013	42,409
Investing Activities
Purchases of available-for-sale investments	(267,777)	(44,547)
Sales and maturities of available-for-sale investments	25,595	46,654
Purchases of property and equipment	(4,543)	(2,303)
Purchases of other assets	(1,446)	(1,107)
Acquisition of business, net of cash acquired	(13,658)
Net cash used in investing activities	(261,829)	(1,303)
Financing Activities
Proceeds from issuance of long-term debt, net	390,000
Payments on debt	(72,500)	(2,500)
Repurchases of common stock		(18,484)
Payment of taxes withheld for vested stock awards	(13,553)	(7,517)
Proceeds from the issuance of common stock	162
Net cash provided by (used in) financing activities	304,109	(28,501)
Increase in cash and cash equivalents	84,293	12,605
Cash and cash equivalents at beginning of period	141,106	114,085
Cash and cash equivalents at end of period	$ 225,399	$ 126,690

Significant Accounting Policies	3 Months Ended
Significant Accounting Policies	Apr. 01, 2017
Significant Accounting Policies
Significant Accounting Policies	1. Significant Accounting Policies Basis of Presentation and Principles of Consolidation The Condensed Consolidated Financial Statements included herein are unaudited; however, they contain all normal recurring accruals and adjustments which, in the opinion of management, are necessary to present fairly the condensed consolidated financial position of Silicon Laboratories Inc. and its subsidiaries (collectively, the “Company”) at April 1, 2017 and December 31, 2016, the condensed consolidated results of its operations for the three months ended April 1, 2017 and April 2, 2016, the Condensed Consolidated Statements of Comprehensive Income for the three months ended April 1, 2017 and April 2, 2016, and the Condensed Consolidated Statements of Cash Flows for the three months ended April 1, 2017 and April 2, 2016. All intercompany balances and transactions have been eliminated in consolidation. The condensed consolidated results of operations for the three months ended April 1, 2017 are not necessarily indicative of the results to be expected for the full year. The accompanying unaudited Condensed Consolidated Financial Statements do not include certain footnotes and financial presentations normally required under U.S. generally accepted accounting principles (GAAP). Therefore, these Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and notes thereto for the year ended December 31, 2016, included in the Company’s Form 10-K filed with the Securities and Exchange Commission (SEC) on February 1, 2017. The Company prepares financial statements on a 52- or 53-week fiscal year that ends on the Saturday closest to December 31. Fiscal 2017 will have 52 weeks and fiscal 2016 had 52 weeks. In a 52-week year, each fiscal quarter consists of 13 weeks. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Among the significant estimates affecting the financial statements are those related to inventories, stock-based compensation, investments in auction-rate securities, acquired intangible assets, goodwill, long-lived assets and income taxes. Actual results could differ from those estimates, and such differences could be material to the financial statements. Reclassifications Certain reclassifications have been made to prior year financial statements to conform to current year presentation. Revenue Recognition Revenues are generated predominately by sales of the Company’s products. The Company recognizes revenue when all of the following criteria are met: 1) there is persuasive evidence that an arrangement exists, 2) delivery of goods has occurred, 3) the sales price is fixed or determinable, and 4) collectibility is reasonably assured. Generally, revenue from product sales to direct customers and contract manufacturers is recognized upon shipment. A portion of the Company’s sales are made to distributors under agreements allowing certain rights of return and price protection related to the final selling price to the end customers. Accordingly, the Company defers revenue and cost of revenue on such sales until the distributors sell the product to the end customers. The net balance of deferred revenue less deferred cost of revenue associated with inventory shipped to a distributor but not yet sold to an end customer is recorded in the deferred income on shipments to distributors liability on the Consolidated Balance Sheet. Such net deferred income balance reflects the Company’s estimate of the impact of rights of return and price protection. A small portion of the Company’s revenues is derived from the sale of patents. The above revenue recognition criteria for patent sales are generally met upon the execution of the patent sale agreement. Recent Accounting Pronouncements In January 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-03, Accounting Changes and Error Corrections (Topic 250) and Investments—Equity Method and Joint Ventures (Topic 323). This ASU amends the disclosure requirements for ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), ASU No. 2016-02, Leases (Topic 842) and ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This ASU states that if a registrant does not know or cannot reasonably estimate the impact that the adoption of the above ASUs is expected to have on the financial statements, then in addition to making a statement to that effect, the registrant should consider additional qualitative financial statement disclosures to assist the reader in assessing the significance of the impact that the standard will have on the financial statements of the registrant when adopted. This ASU was effective upon issuance. The adoption did not have a material impact on the Company’s financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. This ASU eliminates Step 2 from the goodwill impairment test. Instead, an entity should recognize an impairment charge for the amount by which the carrying value exceeds the reporting unit’s fair value, not to exceed the total amount of goodwill allocated to that reporting unit. This ASU is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. The Company is currently evaluating the effect that the adoption of this ASU will have on its financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This ASU clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. This ASU is effective for annual periods beginning after December 15, 2017, including interim periods within those periods. The Company is currently evaluating the effect that the adoption of this ASU will have on its financial statements. In August 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. This ASU requires the recognition of the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The amendments in this ASU should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company early adopted this ASU on January 1, 2017. The adoption did not have a material impact on its financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. This ASU provides guidance on statement of cash flows presentation for eight specific cash flow issues where diversity in practice exists. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the effect of the adoption of this ASU, but anticipates that the adoption will not have a material impact on its financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic326): Measurement of Credit Losses on Financial Instruments. This ASU requires instruments measured at amortized cost to be presented at the net amount expected to be collected. Entities are also required to record allowances for available-for-sale debt securities rather than reduce the carrying amount. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company is currently evaluating the effect of the adoption of this ASU, but anticipates that the adoption will not have a material impact on its financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. This ASU simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The Company adopted this ASU on January 1, 2017. Amendments related to the classification of excess tax benefits on the statement of cash flows were applied prospectively. Prior periods have not been adjusted. In connection with its adoption of ASU 2016-09, the Company recorded excess tax benefits of $3.3 million in the three months ended April 1, 2017. The adoption had no other material impact on the Company’s financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The core principle of Topic 842 is that a lessee should recognize the assets and liabilities that arise from leases. For operating leases, a lessee is required to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in the statement of financial position. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company is currently evaluating the effect that the adoption of this ASU will have on its financial statements. The Company currently expects that most of its operating lease commitments will be subject to the new standard and recognized as right-of-use assets and operating lease liabilities upon the adoption of ASU 2016-02, which will increase the total assets and total liabilities that it reports relative to such amounts prior to adoption. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. This ASU addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. This ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company is currently evaluating the effect of the adoption of this ASU, but anticipates that the adoption will not have a material impact on its financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes the revenue recognition requirements in Accounting Standards Codification (ASC) 605, Revenue Recognition. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance provides a five-step process to achieve that core principle. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which deferred the effective date of ASU 2014-09 to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. In 2016, the FASB issued the following amendments to ASC 606: ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), which clarifies the implementation guidance on principal versus agent considerations; ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies guidance on identification of performance obligations and licensing implementation; ASU No. 2016-12, Compensation—Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which provides clarifying guidance on assessing collectibility, presentation of sales taxes, noncash consideration, contract modifications and completed contracts; and ASU No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which clarifies narrow aspects of ASC 606 or corrects unintended application of the guidance. The standard may be applied retrospectively to each prior period presented (full retrospective method) or retrospectively with the cumulative effect recognized as of the date of initial application (modified retrospective method). Under the new standard, the Company expects the timing of revenue recognition from sales to distributors to be accelerated. The Company will recognize revenue at the time of sale to the distributor, net of the impact of estimated price adjustments and rights of return. The Company currently anticipates adopting this standard using the modified retrospective method. Under this method, incremental disclosures will be provided to present each financial statement line item for fiscal 2018 under the prior standard. The Company has completed an initial assessment of the new standard and is continuing to evaluate the effect that the adoption will have on its financial statements.

Earnings Per Share

3 Months Ended

Apr. 01, 2017

Earnings Per Share

Earnings Per Share

2. Earnings Per Share

The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share data):

	Three Months Ended
	April 1, 2017		April 2, 2016
Net income	$	15,426	$	5,808

Shares used in computing basic earnings per share	42,096		41,629

Effect of dilutive securities:
Stock options and other stock-based awards	934		570
Shares used in computing diluted earnings per share	43,030		42,199

Earnings per share:
Basic	$	0.37	$	0.14
Diluted	$	0.36	$	0.14

For the three months ended April 1, 2017 and April 2, 2016, approximately 0.3 million and 0.8 million shares, respectively, consisting of restricted stock awards (RSUs), market stock awards (MSUs) and stock options, were not included in the diluted earnings per share calculation since the shares were anti-dilutive.

The Company intends to settle the principal amount of its convertible senior notes in cash and any excess value in shares in the event of a conversion. Accordingly, shares issuable upon conversion of the principal amount have been excluded from the calculation of diluted earnings per share. If the market value of the notes under certain prescribed conditions exceeds the conversion amount, the excess will be included in the denominator for the computation of diluted earnings per share using the treasury stock method. As of April 1, 2017, no such shares were included in the denominator for the calculation of diluted earnings per share.

Fair Value of Financial Instruments

3 Months Ended

Apr. 01, 2017

Fair Value of Financial Instruments

Fair Value of Financial Instruments

3. Fair Value of Financial Instruments

The fair values of the Company’s financial instruments are recorded using a hierarchical disclosure framework based upon the level of subjectivity of the inputs used in measuring assets and liabilities. The three levels are described below:

Level 1 - Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2 - Inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

Level 3 - Inputs are unobservable for the asset or liability and are developed based on the best information available in the circumstances, which might include the Company’s own data.

The following summarizes the valuation of the Company’s financial instruments (in thousands). The tables do not include either cash on hand or assets and liabilities that are measured at historical cost or any basis other than fair value.

	Fair Value Measurements at April 1, 2017 Using
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash equivalents:
Money market funds	$	85,090	$	—	$	—	$	85,090
Certificates of deposit	—		32,183		—		32,183
Commercial paper	—		30,582		—		30,582
Municipal bonds	—		6,034		—		6,034
Corporate bonds	—		1,498		—		1,498
Total cash equivalents	$	85,090	$	70,297	$	—	$	155,387

Short-term investments:
Variable-rate demand notes	$	—	$	117,770	$	—	$	117,770
Corporate bonds	—		108,828		—		108,828
Municipal bonds	—		78,555		—		78,555
U.S. government bonds	50,437		—		—		50,437
Asset-backed securities	—		25,519		—		25,519
Agency bonds	—		7,482		—		7,482
Commercial paper	—		6,239		—		6,239
International government bonds	—		1,497		—		1,497
Total short-term investments	$	50,437	$	345,890	$	—	$	396,327

Long-term investments:
Auction rate securities	$	—	$	—	$	5,257	$	5,257
Total long-term investments	$	—	$	—	$	5,257	$	5,257

Total	$	135,527	$	416,187	$	5,257	$	556,971

Liabilities:
Other non-current liabilities:
Contingent consideration	$	—	$	—	$	3,829	$	3,829
Total	$	—	$	—	$	3,829	$	3,829

	Fair Value Measurements at December 31, 2016 Using
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash equivalents:
Money market funds	$	69,432	$	—	$	—	$	69,432
Certificates of deposit	—		7,153		—		7,153
Municipal bonds	—		3,904		—		3,904
Total cash equivalents	$	69,432	$	11,057	$	—	$	80,489

Short-term investments:
Municipal bonds	$	—	$	79,702	$	—	$	79,702
Corporate bonds	—		31,036		—		31,036
Variable-rate demand notes	—		16,400		—		16,400
U.S. government bonds	12,416		—		—		12,416
Asset-backed securities	—		8,173		—		8,173
Commercial paper	—		5,233		—		5,233
International government bonds	—		1,001		—		1,001
Total short-term investments	$	12,416	$	141,545	$	—	$	153,961

Long-term investments:
Auction rate securities	$	—	$	—	$	5,196	$	5,196
Total long-term investments	$	—	$	—	$	5,196	$	5,196

Other assets, net:
Derivative instruments	$	—	$	1,808	$	—	$	1,808
Total	$	—	$	1,808	$	—	$	1,808

Total	$	81,848	$	154,410	$	5,196	$	241,454

Valuation methodology

The Company’s cash equivalents and short-term investments that are classified as Level 2 are valued using non-binding market consensus prices that are corroborated with observable market data; quoted market prices for similar instruments in active markets; or pricing models, such as a discounted cash flow model, with all significant inputs derived from or corroborated with observable market data. Investments classified as Level 3 are valued using a discounted cash flow model. The assumptions used in preparing the discounted cash flow model include estimates for interest rates, amount of cash flows, expected holding periods of the securities and a discount to reflect the Company’s inability to liquidate the securities. The Company’s derivative instruments are valued using discounted cash flow models. The assumptions used in preparing the valuation models include quoted interest swap rates, foreign exchange rates, forward and spot prices for currencies, and market observable data of similar instruments.

The Company’s contingent consideration is valued using a probability weighted discounted cash flow model. The assumptions used in preparing the discounted cash flow model include estimates for the outcome if the milestone goal is achieved, the probability of achieving each outcome and discount rates.

Available-for-sale investments

The Company’s investments typically have original maturities greater than ninety days as of the date of purchase. Investments are reported at fair value, with unrealized gains and losses, net of tax, recorded as a component of accumulated other comprehensive income (loss) in the Consolidated Balance Sheet. The following summarizes the contractual underlying maturities of the Company’s available-for-sale investments at April 1, 2017 (in thousands):

	Cost		Fair Value
Due in one year or less	$	291,314	$	291,287
Due after one year through ten years	149,197		149,157
Due after ten years	117,270		116,527
	$	557,781	$	556,971

The available-for-sale investments that were in a continuous unrealized loss position, aggregated by length of time that individual securities have been in a continuous loss position, were as follows (in thousands):

	Less Than 12 Months					12 Months or Greater					Total
As of April 1, 2017	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Corporate bonds	$	45,299	$	(145	)	$	—	$	—		$	45,299	$	(145	)
Municipal bonds	38,781		(42		)	—		—			38,781		(42		)
U.S. government bonds	28,251		(23		)	—		—			28,251		(23		)
Asset-backed securities	17,478		(22		)	—		—			17,478		(22		)
Auction rate securities	—		—			5,257		(742		)	5,257		(742		)
Agency bonds	3,498		(1		)	—		—			3,498		(1		)
International government bonds	1,497		(2		)	—		—			1,497		(2		)
	$	134,804	$	(235	)	$	5,257	$	(742	)	$	140,061	$	(977	)

	Less Than 12 Months					12 Months or Greater					Total
As of December 31, 2016	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Municipal bonds	$	69,379	$	(140	)	$	—	$	—		$	69,379	$	(140	)
Corporate bonds	18,561		(128		)	—		—			18,561		(128		)
U.S. government bonds	10,364		(16		)	—		—			10,364		(16		)
Auction rate securities	—		—			5,196		(804		)	5,196		(804		)
Asset-backed securities	3,176		(4		)	—		—			3,176		(4		)
	$	101,480	$	(288	)	$	5,196	$	(804	)	$	106,676	$	(1,092	)

The gross unrealized losses as of April 1, 2017 and December 31, 2016 were due primarily to the illiquidity of the Company’s auction-rate securities and, to a lesser extent, to changes in market interest rates. The Company’s auction-rate securities have been illiquid since 2008 when auctions for the securities failed because sell orders exceeded buy orders. These securities have a contractual maturity date of 2046 at April 1, 2017. The Company is unable to predict if these funds will become available before their maturity date.

The Company does not expect to need access to the capital represented by any of its auction-rate securities prior to their maturities. The Company does not intend to sell, and believes it is not more likely than not that it will be required to sell, its auction-rate securities before their anticipated recovery in market value or final settlement at the underlying par value. The Company believes that the credit ratings and credit support of the security issuers indicate that they have the ability to settle the securities at par value. As such, the Company has determined that no other-than-temporary impairment losses existed as of April 1, 2017.

At April 1, 2017 and December 31, 2016, there were no material unrealized gains associated with the Company’s available-for-sale investments.

Level 3 fair value measurements

The following summarizes quantitative information about Level 3 fair value measurements.

Auction rate securities

Fair Value at April 1, 2017 (000s)		Valuation Technique	Unobservable Input	Weighted Average
$	5,257	Discounted cash flow	Estimated yield	0.9%

			Expected holding period	10 years

			Estimated discount rate	3.56%

The Company has followed an established internal control procedure used in valuing auction rate securities. The procedure involves the analysis of valuation techniques and evaluation of unobservable inputs commonly used by market participants to price similar instruments, and which have been demonstrated to provide reasonable estimates of prices obtained in actual market transactions. Outputs from the valuation process are assessed against various market sources when they are available, including marketplace quotes, recent trades of similar illiquid securities, benchmark indices and independent pricing services. The technique and unobservable input parameters may be recalibrated periodically to achieve an appropriate estimation of the fair value of the securities.

Significant changes in any of the unobservable inputs used in the fair value measurement of auction rate securities in isolation could result in a significantly lower or higher fair value measurement. An increase in expected yield would result in a higher fair value measurement, whereas an increase in expected holding period or estimated discount rate would result in a lower fair value measurement. Generally, a change in the assumptions used for expected holding period is accompanied by a directionally similar change in the assumptions used for estimated yield and discount rate.

Contingent consideration

Fair Value at April 1, 2017 (000s)		Valuation Technique	Unobservable Input	Weighted Average
$	3,829	Discounted cash flow	Expected term	9 months

			Estimated discount rate	12.0%

The Company has followed an established internal control procedure used in valuing contingent consideration. The valuation of contingent consideration for the Zentri acquisition is based on a discounted cash flow model. The fair value of this valuation is estimated on a quarterly basis through a collaborative effort by the Company’s sales, marketing and finance departments.

Significant changes in any of the unobservable inputs used in the fair value measurement of contingent consideration in isolation could result in a significantly lower or higher fair value. A change in projected revenue would be accompanied by a directionally similar change in fair value.

The following summarizes the activity in Level 3 financial instruments for the three months ended April 1, 2017 (in thousands):

Assets

Auction Rate Securities	Three Months Ended
Beginning balance	$	5,196
Gain included in other comprehensive loss	61
Balance at April 1, 2017	$	5,257

Liabilities

Contingent Consideration (1)	Three Months Ended
Beginning balance	$	—
Issues	3,829
Balance at April 1, 2017	$	3,829

(1) In connection with the acquisition of Zentri, the Company recorded contingent consideration based upon the expected achievement of a milestone goal. Changes to the fair value of contingent consideration due to changes in assumptions used in preparing the valuation model are recorded in selling, general and administrative expenses in the Consolidated Statement of Income.

Fair values of other financial instruments

The Company’s debt is recorded at cost, but is measured at fair value for disclosure purposes. The Company’s convertible senior notes are traded in less active markets and are therefore classified as a Level 2 fair value measurement. The fair value of the convertible senior notes at April 1, 2017 was $426.3 million. The Company’s prior debt under the Credit Facility bore interest at the Eurodollar rate plus an applicable margin. Fair value was estimated based on Level 2 inputs, using a discounted cash flow analysis of future principal payments and projected interest based on current market rates. As of April 1, 2017 and December 31, 2016, the fair value of the Company’s debt under the Credit Facility was approximately $0.0 and $72.5 million, respectively.

The Company’s other financial instruments, including cash, accounts receivable and accounts payable, are recorded at amounts that approximate their fair values due to their short maturities.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Derivative Financial Instruments

3 Months Ended

Apr. 01, 2017

Derivative Financial Instruments

Derivative Financial Instruments

4. Derivative Financial Instruments

The Company uses derivative financial instruments to manage certain exposures to the variability of interest rates and foreign currency exchange rates. The Company’s objective is to offset increases and decreases in expenses resulting from these exposures with gains and losses on the derivative contracts, thereby reducing volatility of earnings. The Company does not use derivative contracts for speculative or trading purposes. The Company recognizes derivatives, on a gross basis, in the Consolidated Balance Sheet at fair value. Cash flows from derivatives are classified according to the nature of the cash receipt or payment in the Consolidated Statement of Cash Flows.

Interest Rate Swaps

The Company is exposed to interest rate fluctuations in the normal course of its business, including through its Credit Facility. The interest payments on the facility are calculated using a variable-rate of interest. The Company entered into an interest rate swap agreement with an original notional value of $72.5 million and, effectively, converted the Eurodollar portion of the variable-rate interest payments to fixed-rate interest payments through July 2020. The Company terminated the swap agreement on March 6, 2017 in connection with the payoff of its Credit Facility.

The Company’s interest rate swap agreement was designated and qualified as a cash flow hedge. The effective portion of the gain or loss on the interest rate swap was recorded in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity and was subsequently recognized as interest expense in the Consolidated Statement of Income when the hedged exposure affected earnings. The termination of the swap agreement resulted in the reclassification of $1.8 million of unrealized gains that were previously recorded in accumulated other comprehensive income (loss) into earnings during the three months ended April 1, 2017. The Company did not discontinue any other cash flow hedges in any of the periods presented.

The Company’s derivative financial instrument in cash flow hedging relationships consisted of the following (in thousands):

		Fair Value
	Balance Sheet Location	April 1, 2017		December 31, 2016
Interest rate swap	Other assets, net	$	—	$	1,808

The before-tax effect of derivative instruments in cash flow hedging relationships was as follows (in thousands):

	Gain (Loss) Recognized in OCI on Derivatives (Effective Portion) during the:						Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) during the:
	Three Months Ended					Location of Loss	Three Months Ended
	April 1, 2017		April 2, 2016			Reclassified into Income	April 1, 2017		April 2, 2016
Interest rate swaps	$	—	$	(286	)	Interest expense	$	1,808	$	(66	)

Foreign Currency Forward Contracts

The Company uses foreign currency forward contracts to manage exposure to foreign exchange risk. These instruments are used to reduce the earnings impact that exchange rate fluctuations have on non-U.S. dollar balance sheet exposures. The Company recognizes gains and losses on the foreign currency forward contracts in other, net in the Consolidated Statement of Income in the same period as the remeasurement loss and gain of the related foreign currency denominated asset or liability. The Company does not apply hedge accounting to its foreign currency derivative instruments.

As of April 1, 2017 and April 2, 2016, the Company held one foreign currency forward contract denominated in Norwegian Krone with a notional value of $4.0 million and $4.8 million, respectively. The fair value of the contracts was not material as of April 1, 2017 or April 2, 2016. The contract held as of April 1, 2017 has a maturity date of June 28, 2017 and it was not designated as a hedging instrument.

The before-tax effect of derivative instruments not designated as hedging instruments was as follows (in thousands):

	Three Months Ended
Gain (Loss) Recognized in Income	April 1, 2017			April 2, 2016			Location
Foreign currency forward contracts	$	(94	)	$	(300	)	Other, net

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

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+ Details

Balance Sheet Details

3 Months Ended

Apr. 01, 2017

Balance Sheet Details

Balance Sheet Details

5. Balance Sheet Details

The following shows the details of selected Condensed Consolidated Balance Sheet items (in thousands):

Inventories

	April 1, 2017		December 31, 2016
Work in progress	$	42,493	$	40,755
Finished goods	18,815		18,823
	$	61,308	$	59,578

Acquisitions	3 Months Ended
Acquisitions	Apr. 01, 2017
Acquisitions
Acquisitions	6. Acquisitions Zentri On January 20, 2017, the Company acquired Zentri, Inc., a private company. Zentri is an innovator in low-power, cloud-connected Wi-Fi® technologies for the Internet of Things (IoT). The Company acquired Zentri for approximately $18.1 million, including initial cash consideration of approximately $14.3 million, and potential additional consideration with an estimated fair value of approximately $3.8 million at the date of acquisition. The amount of potential additional consideration is up to approximately $10.0 million based on fiscal 2017 revenue from certain Zentri products. The purchase price was allocated as follows: intangible assets—$6.7 million; goodwill—$12.5 million; and other net liabilities—$1.1 million. The goodwill is not deductible for tax purposes. The allocation of the purchase price is preliminary and subject to change, primarily for the valuation of certain assets and accruals and the finalization of income tax matters. Accordingly, adjustments may be made to the values of the assets acquired and liabilities assumed as additional information is obtained about the facts and circumstances that existed at the valuation date. Pro forma information related to this acquisition has not been presented because it would not be materially different from amounts reported.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

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+ Details

Debt

3 Months Ended

Apr. 01, 2017

Debt

Debt

7. Debt

1.375% Convertible Senior Notes

On March 6, 2017, the Company completed a private offering of $400 million principal amount convertible senior notes (the “Notes”). The Notes bear interest semi-annually at a rate of 1.375% per year and will mature on March 1, 2022, unless repurchased, redeemed or converted at an earlier date. The Company used $72.5 million of the proceeds to pay off the remaining balance of its Amended Credit Agreement.

The Notes are convertible at an initial conversion rate of 10.7744 shares of common stock per $1,000 principal amount of the Notes, which is equivalent to a conversion price of approximately $92.81 per share. The conversion rate is subject to adjustment under certain circumstances. Holders may convert the Notes under the following circumstances: during any calendar quarter after the calendar quarter ending on June 30, 2017 if the closing price of the Company’s common stock for at least 20 trading days in the 30 consecutive trading days ending on the last trading day of the preceding calendar quarter is greater than or equal to 130% of the conversion price of the Notes; during the five business day period after any ten consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the closing sale price of our common stock and the conversion rate on each such trading day; if specified distributions or corporate events occur; if the Notes are called for redemption; or at any time after December 1, 2021. The Company may redeem all or any portion of the Notes, at its option, on or after March 6, 2020, if the last reported sale price of the Company’s common stock has been at least 130% of the conversion price then in effect for at least 20 trading days during any 30 consecutive trading day period. Upon conversion, the Notes may be settled in cash, shares of the Company’s common stock or a combination of cash and shares, at the Company’s election.

The principal balance of the Notes was separated into liability and equity components, and was recorded initially at fair value. The excess of the principal amount of the liability component over its carrying amount represents the debt discount, which is amortized to interest expense over the term of the Notes using the effective interest method. The carrying amount of the liability component was estimated by discounting the contractual cash flows of similar non-convertible debt at an appropriate market rate at the date of issuance.

The Company incurred debt issuance costs of approximately $10.6 million, which was allocated to the liability and equity components in proportion to the allocation of the proceeds. The costs allocated to the liability component are being amortized as interest expense over the term of the Notes using the effective interest method.

The carrying amount of the Notes consisted of the following (in thousands):

	April 1, 2017
Liability component
Principal	$	400,000
Unamortized debt discount	(58,561		)
Unamortized debt issuance costs	(8,937		)
Net carrying amount	$	332,502

Equity component
Net carrying amount	$	57,718

The liability component of the Notes is recorded in long-term debt on the Consolidated Balance Sheet. The equity component of the Notes is recorded in additional paid-in capital. The effective interest rate for the liability component was 4.75%. As of April 1, 2017, the remaining period over which the debt discount and debt issuance costs will be amortized was 4.9 years.

Interest expense related to the Notes was comprised of the following (in thousands):

	Three Months Ended
	April 1, 2017
Contractual interest expense	$	382
Amortization of debt discount	754
Amortization of debt issuance costs	115
	$	1,251

Amended Credit Agreement

On July 31, 2012, the Company and certain of its domestic subsidiaries (the “Guarantors”) entered into a $230 million five-year Credit Agreement (the “Credit Agreement”), which consisted of a $100 million Term Loan Facility and a $130 million Revolving Credit Facility. On July 24, 2015, the Company and the Guarantors amended the Credit Agreement (the “Amended Credit Agreement”) in order to, among other things, increase the borrowing capacity under the Revolving Credit Facility to $300 million (the “Credit Facility”), eliminate the Term Loan Facility and extend the maturity date to five years from the closing date. On July 24, 2015, the Company borrowed $82.5 million under the Amended Credit Agreement and paid off the remaining balance of its Term Loan Facility. In connection with the Company’s offering of the Notes, it entered into a second amendment to the Credit Agreement (the “Second Amended Credit Agreement”) and paid off the remaining balance of $72.5 million.

The Second Amended Credit Agreement retained the key terms and provisions of the first Amended Credit Agreement, including a $25 million letter of credit sublimit and a $10 million swingline loan sublimit. The Company also has an option to increase the size of the borrowing capacity by up to an aggregate of $200 million in additional commitments, subject to certain conditions.

The Revolving Credit Facility, other than swingline loans, will bear interest at the Eurodollar rate plus an applicable margin or, at the option of the Company, a base rate (defined as the highest of the Wells Fargo prime rate, the Federal Funds rate plus 0.50% and the Eurodollar Base Rate plus 1.00%) plus an applicable margin. Swingline loans accrue interest at the base rate plus the applicable margin for base rate loans. The applicable margins for the Eurodollar rate loans range from 1.25% to 2.00% and for base rate loans range from 0.25% to 1.00%, depending in each case, on the leverage ratio as defined in the Agreement.

The Second Amended Credit Agreement contains various conditions, covenants and representations with which the Company must be in compliance in order to borrow funds and to avoid an event of default, including financial covenants that the Company must maintain a leverage ratio (funded debt/EBITDA) of no more than 3.00 to 1 and a minimum fixed charge coverage ratio (EBITDA/interest payments, income taxes and capital expenditures) of no less than 1.25 to 1. As of April 1, 2017, the Company was in compliance with all covenants of the Second Amended Credit Agreement. The Company’s obligations under the Second Amended Credit Agreement are guaranteed by the Guarantors and are secured by a security interest in substantially all assets of the Company and the Guarantors.

Stockholders' Equity

3 Months Ended

Apr. 01, 2017

Stockholders' Equity

Stockholders' Equity

8. Stockholders’ Equity

Common Stock

The Company issued 0.5 million shares of common stock during the three months ended April 1, 2017.

Share Repurchase Programs

The Board of Directors authorized the following share repurchase programs (in thousands):

Program Authorization Date	Program Termination Date	Program Amount
January 2017	December 2017	$	100,000
August 2015	December 2016	$	100,000

These programs allow for repurchases to be made in the open market or in private transactions, including structured or accelerated transactions, subject to applicable legal requirements and market conditions. The Company did not repurchase any shares of its common stock during the three months ended April 1, 2017. The Company repurchased 0.4 million shares of its common stock for $18.5 million during the three months ended April 2, 2016. These shares were retired upon repurchase.

Accumulated Other Comprehensive Income (Loss)

The components of accumulated other comprehensive income (loss), net of taxes, were as follows (in thousands):

	Unrealized Gain on Cash Flow Hedge			Net Unrealized Losses on Available-For-Sale Securities			Total
Balance at December 31, 2016	$	1,175		$	(683	)	$	492

Other comprehensive income (loss) before reclassifications	—			158			158
Amount reclassified from accumulated other comprehensive income (loss)	(1,175		)	—			(1,175		)
Net change for the period	(1,175		)	158			(1,017		)

Balance at April 1, 2017	$	—		$	(525	)	$	(525	)

Reclassifications From Accumulated Other Comprehensive Income (Loss)

The following table summarizes the effect on net income from reclassifications out of accumulated other comprehensive income (loss) (in thousands):

	Three Months Ended
Reclassification	April 1, 2017			April 2, 2016
Gains (losses) on cash flow hedges to:
Interest expense	$	1,808		$	(66	)

Income tax benefit	(633		)	23

Total reclassifications	$	1,175		$	(43	)

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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+ Details

Stock-Based Compensation

3 Months Ended

Apr. 01, 2017

Stock-Based Compensation

Stock-Based Compensation

9. Stock-Based Compensation

In fiscal 2009, the stockholders of the Company approved the 2009 Stock Incentive Plan (the “2009 Plan”) and the 2009 Employee Stock Purchase Plan (the “2009 Purchase Plan”). In fiscal 2014, the stockholders of the Company approved amendments to both the 2009 Plan and the 2009 Purchase Plan. The amendments authorized additional shares of common stock for issuance, to comply with changes in applicable law, improve the Company’s corporate governance and to implement other best practices. The amended plans are currently effective.

Stock-based compensation costs are based on the fair values on the date of grant for stock awards and stock options and on the date of enrollment for the employee stock purchase plans. The fair values of stock awards (such as RSUs, performance stock units (PSUs) and restricted stock awards (RSAs)) are estimated based on their intrinsic values. The fair values of MSUs are estimated using a Monte Carlo simulation. The fair values of stock options and employee stock purchase plans are estimated using the Black-Scholes option-pricing model.

The following table presents details of stock-based compensation costs recognized in the Condensed Consolidated Statements of Income (in thousands):

	Three Months Ended
	April 1, 2017		April 2, 2016
Cost of revenues	$	258	$	266
Research and development	5,246		4,910
Selling, general and administrative	4,982		5,168
	10,486		10,344
Income tax benefit	5,282		2,236
	$	5,204	$	8,108

The increase in income tax benefit in the three months ended April 1, 2017 was primarily due to the recognition of excess tax benefits in connection with the Company’s adoption of ASU 2016-09. The Company had approximately $88.8 million of total unrecognized compensation costs related to granted stock options and awards as of April 1, 2017 that are expected to be recognized over a weighted-average period of approximately 2.5 years. There were no significant stock-based compensation costs capitalized into assets in any of the periods presented.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Apr. 01, 2017
Commitments and Contingencies
Commitments and Contingencies	10. Commitments and Contingencies Patent Litigation On January 21, 2014, Cresta Technology Corporation (“Cresta Technology”), a Delaware corporation, filed a lawsuit against the Company, Samsung Electronics Co., Ltd., Samsung Electronics America, Inc., LG Electronics Inc. and LG Electronics U.S.A., Inc. in the United States District Court in the District of Delaware, alleging infringement of three United States Patents (the “Cresta Patents”). The Delaware District Court action has been stayed. The Company challenged the validity of the claims of the Cresta Patents through a series of Inter-Partes Review (IPR) proceedings at the Patent Trial and Appeal Board (PTAB) of the United States Patent and Trademark Office (USPTO). On October 21, 2015, the USPTO issued final written decisions on a first set of reviewed claims finding all of the reviewed claims invalid. The Federal Circuit summarily affirmed the USPTO’s first determination on November 8, 2016 and the mandate issued on December 16, 2016, rendering the USPTO’s determination final. On August 11, 2016, the PTAB issued its final written decisions in proceedings against a second set of claims in the Cresta Patents and found these claims unpatentable. On October 13, 2016, the patent owner, now known as CF Crespe LLC, filed a notice of appeal with the Federal Circuit. That appeal is currently pending. No hearing date has been set. On March 18, 2016, Cresta Technology filed for chapter 7 bankruptcy in the United States Bankruptcy Court for the Northern District of California. On May 13, 2016, the Bankruptcy Court approved an agreement for DBD Credit Funding LLC (“DBD”) to buy Cresta Technology’s entire IP portfolio and certain related litigation. Following that sale, DBD (through an apparent assignee, CF Crespe LLC) has substituted in the Delaware District Court action and the appeal proceedings at the U.S. Court of Appeals for the Federal Circuit for the second set of IPRs. On July 16, 2014, the Company filed a lawsuit against Cresta Technology in the United States District Court in the Northern District of California alleging infringement of six United States Patents. The Company is seeking a permanent injunction and an award of damages and attorney fees. As a result of the chapter 7 bankruptcy filing by Cresta Technology, these proceedings were stayed. However, as a result of the May 13, 2016 sale order by the Bankruptcy Court, DBD and CF Crespe LLC were ordered to substitute in as Defendant for Cresta Technology. DBD and CF Crespe LLC have appealed the Bankruptcy Court’s order in that regard. Subject to that appeal, the Company’s patent infringement trial against DBD and CF Crespe LLC is set to begin October 2, 2017. As is customary in the semiconductor industry, the Company provides indemnification protection to its customers for intellectual property claims related to the Company’s products. The Company has not accrued any material liability on its Consolidated Balance Sheet related to such indemnification obligations in connection with the Cresta Technology litigation. The Company intends to continue to vigorously defend against Cresta Technology’s (now DBD and CF Crespe LLC’s) allegations and to continue to pursue its claims against DBD and CF Crespe LLC and their patents. At this time, the Company cannot predict the outcome of these matters or the resulting financial impact to it, if any. Other The Company is involved in various other legal proceedings that have arisen in the normal course of business. While the ultimate results of these matters cannot be predicted with certainty, the Company does not expect them to have a material adverse effect on its Consolidated Financial Statements.

Related Party Transactions	3 Months Ended
Related Party Transactions	Apr. 01, 2017
Related Party Transactions
Related Party Transactions	11. Related Party Transactions In August 2016, Bill Bock, a member of the Company’s board of directors, joined the board of directors of Spredfast. Spredfast has been a tenant in one of the buildings at the Company’s headquarters in Austin, Texas since May 2013. During the three months ended April 1, 2017 and April 2, 2016, the Company received payments from Spredfast of $0.9 million and $0.8 million, respectively, in connection with the leased facilities.

Income Taxes	3 Months Ended
Income Taxes	Apr. 01, 2017
Income Taxes
Income Taxes	12. Income Taxes Provision (benefit) for income taxes includes both domestic and foreign income taxes at the applicable tax rates adjusted for non-deductible expenses, research and development tax credits and other permanent differences. Income tax expense was $(2.0) million and $0.3 million for the three months ended April 1, 2017 and April 2, 2016, resulting in effective tax rates of (14.6)% and 4.4%, respectively. The effective tax rate for the three months ended April 1, 2017 decreased from the prior period primarily due to excess tax benefits from stock-based compensation from the adoption of ASU 2016-09 offset by a decrease in the foreign tax rate benefit. On July 27, 2015, the U.S. Tax Court (the “Court”) issued an opinion in Altera Corp. v. Commissioner related to the treatment of stock-based compensation expense in an intercompany cost-sharing arrangement. A final decision was entered by the Court on December 1, 2015. In its opinion, the Court accepted Altera’s position of excluding stock-based compensation from its cost-sharing arrangement and concluded that the related U.S. Treasury Regulations were invalid. In February 2016, the U.S. Internal Revenue Service (the “IRS”) appealed the decision to the U.S Court of Appeals for the Ninth Circuit. Although the IRS has appealed the decision, and the U.S. Treasury has not withdrawn the requirement to include stock-based compensation from its regulations, based on the facts and circumstances of the Tax Court Case, the Company believes that it is more likely than not that the Tax Court decision will be upheld. Therefore, the Company continues to reflect the effects of the decision in its Condensed Consolidated Financial Statements. This change to cost-sharing is expected to increase the Company’s cumulative foreign earnings at the time of final resolution of the case. As such, the Company continues to accrue a deferred tax liability for the U.S. tax cost of potential repatriation of the associated foreign earnings because at this time, the Company cannot reasonably conclude that it will have the ability and intent to indefinitely reinvest these contingent earnings. The overall net impact on the Company’s Condensed Consolidated Financial Statements is not material. The Company will continue to monitor ongoing developments and potential impacts to its Consolidated Financial Statements. As of April 1, 2017, the Company had gross unrecognized tax benefits of $3.6 million, of which $2.2 million would affect the effective tax rate if recognized. The Company recognizes interest and penalties related to unrecognized tax benefits in the provision (benefit) for income taxes. These amounts were not material for any of the periods presented. Tax years 2012 through 2016 remain open to examination by the major taxing jurisdictions to which the Company is subject. The Company is not currently under audit in any major taxing jurisdiction. The Company believes it is reasonably possible that the gross unrecognized tax benefits will decrease by approximately $1.9 million in the next 12 months due to the lapse of the statute of limitations applicable to tax deductions and tax credits claimed on prior year tax returns.

Significant Accounting Policies (Policies)	3 Months Ended
Significant Accounting Policies (Policies)	Apr. 01, 2017
Significant Accounting Policies
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Among the significant estimates affecting the financial statements are those related to inventories, stock-based compensation, investments in auction-rate securities, acquired intangible assets, goodwill, long-lived assets and income taxes. Actual results could differ from those estimates, and such differences could be material to the financial statements.
Reclassifications	Reclassifications Certain reclassifications have been made to prior year financial statements to conform to current year presentation.
Revenue Recognition	Revenue Recognition Revenues are generated predominately by sales of the Company’s products. The Company recognizes revenue when all of the following criteria are met: 1) there is persuasive evidence that an arrangement exists, 2) delivery of goods has occurred, 3) the sales price is fixed or determinable, and 4) collectibility is reasonably assured. Generally, revenue from product sales to direct customers and contract manufacturers is recognized upon shipment. A portion of the Company’s sales are made to distributors under agreements allowing certain rights of return and price protection related to the final selling price to the end customers. Accordingly, the Company defers revenue and cost of revenue on such sales until the distributors sell the product to the end customers. The net balance of deferred revenue less deferred cost of revenue associated with inventory shipped to a distributor but not yet sold to an end customer is recorded in the deferred income on shipments to distributors liability on the Consolidated Balance Sheet. Such net deferred income balance reflects the Company’s estimate of the impact of rights of return and price protection. A small portion of the Company’s revenues is derived from the sale of patents. The above revenue recognition criteria for patent sales are generally met upon the execution of the patent sale agreement.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In January 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-03, Accounting Changes and Error Corrections (Topic 250) and Investments—Equity Method and Joint Ventures (Topic 323). This ASU amends the disclosure requirements for ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), ASU No. 2016-02, Leases (Topic 842) and ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This ASU states that if a registrant does not know or cannot reasonably estimate the impact that the adoption of the above ASUs is expected to have on the financial statements, then in addition to making a statement to that effect, the registrant should consider additional qualitative financial statement disclosures to assist the reader in assessing the significance of the impact that the standard will have on the financial statements of the registrant when adopted. This ASU was effective upon issuance. The adoption did not have a material impact on the Company’s financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. This ASU eliminates Step 2 from the goodwill impairment test. Instead, an entity should recognize an impairment charge for the amount by which the carrying value exceeds the reporting unit’s fair value, not to exceed the total amount of goodwill allocated to that reporting unit. This ASU is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. The Company is currently evaluating the effect that the adoption of this ASU will have on its financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This ASU clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. This ASU is effective for annual periods beginning after December 15, 2017, including interim periods within those periods. The Company is currently evaluating the effect that the adoption of this ASU will have on its financial statements. In August 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. This ASU requires the recognition of the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The amendments in this ASU should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company early adopted this ASU on January 1, 2017. The adoption did not have a material impact on its financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. This ASU provides guidance on statement of cash flows presentation for eight specific cash flow issues where diversity in practice exists. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the effect of the adoption of this ASU, but anticipates that the adoption will not have a material impact on its financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic326): Measurement of Credit Losses on Financial Instruments. This ASU requires instruments measured at amortized cost to be presented at the net amount expected to be collected. Entities are also required to record allowances for available-for-sale debt securities rather than reduce the carrying amount. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company is currently evaluating the effect of the adoption of this ASU, but anticipates that the adoption will not have a material impact on its financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. This ASU simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The Company adopted this ASU on January 1, 2017. Amendments related to the classification of excess tax benefits on the statement of cash flows were applied prospectively. Prior periods have not been adjusted. In connection with its adoption of ASU 2016-09, the Company recorded excess tax benefits of $3.3 million in the three months ended April 1, 2017. The adoption had no other material impact on the Company’s financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The core principle of Topic 842 is that a lessee should recognize the assets and liabilities that arise from leases. For operating leases, a lessee is required to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in the statement of financial position. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company is currently evaluating the effect that the adoption of this ASU will have on its financial statements. The Company currently expects that most of its operating lease commitments will be subject to the new standard and recognized as right-of-use assets and operating lease liabilities upon the adoption of ASU 2016-02, which will increase the total assets and total liabilities that it reports relative to such amounts prior to adoption. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. This ASU addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. This ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company is currently evaluating the effect of the adoption of this ASU, but anticipates that the adoption will not have a material impact on its financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes the revenue recognition requirements in Accounting Standards Codification (ASC) 605, Revenue Recognition. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance provides a five-step process to achieve that core principle. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which deferred the effective date of ASU 2014-09 to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. In 2016, the FASB issued the following amendments to ASC 606: ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), which clarifies the implementation guidance on principal versus agent considerations; ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies guidance on identification of performance obligations and licensing implementation; ASU No. 2016-12, Compensation—Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which provides clarifying guidance on assessing collectibility, presentation of sales taxes, noncash consideration, contract modifications and completed contracts; and ASU No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which clarifies narrow aspects of ASC 606 or corrects unintended application of the guidance. The standard may be applied retrospectively to each prior period presented (full retrospective method) or retrospectively with the cumulative effect recognized as of the date of initial application (modified retrospective method). Under the new standard, the Company expects the timing of revenue recognition from sales to distributors to be accelerated. The Company will recognize revenue at the time of sale to the distributor, net of the impact of estimated price adjustments and rights of return. The Company currently anticipates adopting this standard using the modified retrospective method. Under this method, incremental disclosures will be provided to present each financial statement line item for fiscal 2018 under the prior standard. The Company has completed an initial assessment of the new standard and is continuing to evaluate the effect that the adoption will have on its financial statements.

Earnings Per Share (Tables)

3 Months Ended

Apr. 01, 2017

Earnings Per Share

Schedule of computation of basic and diluted earnings per share

The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share data):

	Three Months Ended
	April 1, 2017		April 2, 2016
Net income	$	15,426	$	5,808

Shares used in computing basic earnings per share	42,096		41,629

Effect of dilutive securities:
Stock options and other stock-based awards	934		570
Shares used in computing diluted earnings per share	43,030		42,199

Earnings per share:
Basic	$	0.37	$	0.14
Diluted	$	0.36	$	0.14

Fair Value of Financial Instruments (Tables)

3 Months Ended

Apr. 01, 2017

Fair Value of Financial Instruments

Financial assets and liabilities measured at fair value on a recurring basis

	Fair Value Measurements at April 1, 2017 Using
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash equivalents:
Money market funds	$	85,090	$	—	$	—	$	85,090
Certificates of deposit	—		32,183		—		32,183
Commercial paper	—		30,582		—		30,582
Municipal bonds	—		6,034		—		6,034
Corporate bonds	—		1,498		—		1,498
Total cash equivalents	$	85,090	$	70,297	$	—	$	155,387

Short-term investments:
Variable-rate demand notes	$	—	$	117,770	$	—	$	117,770
Corporate bonds	—		108,828		—		108,828
Municipal bonds	—		78,555		—		78,555
U.S. government bonds	50,437		—		—		50,437
Asset-backed securities	—		25,519		—		25,519
Agency bonds	—		7,482		—		7,482
Commercial paper	—		6,239		—		6,239
International government bonds	—		1,497		—		1,497
Total short-term investments	$	50,437	$	345,890	$	—	$	396,327

Long-term investments:
Auction rate securities	$	—	$	—	$	5,257	$	5,257
Total long-term investments	$	—	$	—	$	5,257	$	5,257

Total	$	135,527	$	416,187	$	5,257	$	556,971

Liabilities:
Other non-current liabilities:
Contingent consideration	$	—	$	—	$	3,829	$	3,829
Total	$	—	$	—	$	3,829	$	3,829

	Fair Value Measurements at December 31, 2016 Using
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash equivalents:
Money market funds	$	69,432	$	—	$	—	$	69,432
Certificates of deposit	—		7,153		—		7,153
Municipal bonds	—		3,904		—		3,904
Total cash equivalents	$	69,432	$	11,057	$	—	$	80,489

Short-term investments:
Municipal bonds	$	—	$	79,702	$	—	$	79,702
Corporate bonds	—		31,036		—		31,036
Variable-rate demand notes	—		16,400		—		16,400
U.S. government bonds	12,416		—		—		12,416
Asset-backed securities	—		8,173		—		8,173
Commercial paper	—		5,233		—		5,233
International government bonds	—		1,001		—		1,001
Total short-term investments	$	12,416	$	141,545	$	—	$	153,961

Long-term investments:
Auction rate securities	$	—	$	—	$	5,196	$	5,196
Total long-term investments	$	—	$	—	$	5,196	$	5,196

Other assets, net:
Derivative instruments	$	—	$	1,808	$	—	$	1,808
Total	$	—	$	1,808	$	—	$	1,808

Total	$	81,848	$	154,410	$	5,196	$	241,454

Summarization of contractual underlying maturities of available-for-sale investments

The following summarizes the contractual underlying maturities of the Company’s available-for-sale investments at April 1, 2017 (in thousands):

	Cost		Fair Value
Due in one year or less	$	291,314	$	291,287
Due after one year through ten years	149,197		149,157
Due after ten years	117,270		116,527
	$	557,781	$	556,971

Schedule of available-for-sale investments in continuous unrealized loss position by length of time

	Less Than 12 Months					12 Months or Greater					Total
As of April 1, 2017	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Corporate bonds	$	45,299	$	(145	)	$	—	$	—		$	45,299	$	(145	)
Municipal bonds	38,781		(42		)	—		—			38,781		(42		)
U.S. government bonds	28,251		(23		)	—		—			28,251		(23		)
Asset-backed securities	17,478		(22		)	—		—			17,478		(22		)
Auction rate securities	—		—			5,257		(742		)	5,257		(742		)
Agency bonds	3,498		(1		)	—		—			3,498		(1		)
International government bonds	1,497		(2		)	—		—			1,497		(2		)
	$	134,804	$	(235	)	$	5,257	$	(742	)	$	140,061	$	(977	)

	Less Than 12 Months					12 Months or Greater					Total
As of December 31, 2016	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Municipal bonds	$	69,379	$	(140	)	$	—	$	—		$	69,379	$	(140	)
Corporate bonds	18,561		(128		)	—		—			18,561		(128		)
U.S. government bonds	10,364		(16		)	—		—			10,364		(16		)
Auction rate securities	—		—			5,196		(804		)	5,196		(804		)
Asset-backed securities	3,176		(4		)	—		—			3,176		(4		)
	$	101,480	$	(288	)	$	5,196	$	(804	)	$	106,676	$	(1,092	)

Summary of quantitative information about level 3 asset fair value measurements

Auction rate securities

Fair Value at April 1, 2017 (000s)		Valuation Technique	Unobservable Input	Weighted Average
$	5,257	Discounted cash flow	Estimated yield	0.9%

			Expected holding period	10 years

			Estimated discount rate	3.56%

Contingent consideration

Fair Value at April 1, 2017 (000s)		Valuation Technique	Unobservable Input	Weighted Average
$	3,829	Discounted cash flow	Expected term	9 months

			Estimated discount rate	12.0%

Summary of activity in Level 3 financial instruments

The following summarizes the activity in Level 3 financial instruments for the three months ended April 1, 2017 (in thousands):

Assets

Auction Rate Securities	Three Months Ended
Beginning balance	$	5,196
Gain included in other comprehensive loss	61
Balance at April 1, 2017	$	5,257

Liabilities

Contingent Consideration (1)	Three Months Ended
Beginning balance	$	—
Issues	3,829
Balance at April 1, 2017	$	3,829

Derivative Financial Instruments (Tables)

3 Months Ended

Apr. 01, 2017

Derivative Financial Instruments

Schedule of derivative financial instrument

The Company’s derivative financial instrument in cash flow hedging relationships consisted of the following (in thousands):

		Fair Value
	Balance Sheet Location	April 1, 2017		December 31, 2016
Interest rate swap	Other assets, net	$	—	$	1,808

Schedule of before-tax effect of derivative instruments in cash flow hedging relationships

The before-tax effect of derivative instruments in cash flow hedging relationships was as follows (in thousands):

	Gain (Loss) Recognized in OCI on Derivatives (Effective Portion) during the:						Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) during the:
	Three Months Ended					Location of Loss	Three Months Ended
	April 1, 2017		April 2, 2016			Reclassified into Income	April 1, 2017		April 2, 2016
Interest rate swaps	$	—	$	(286	)	Interest expense	$	1,808	$	(66	)

Schedule of before-tax effect of derivative instruments not designated as hedging instruments

The before-tax effect of derivative instruments not designated as hedging instruments was as follows (in thousands):

	Three Months Ended
Gain (Loss) Recognized in Income	April 1, 2017			April 2, 2016			Location
Foreign currency forward contracts	$	(94	)	$	(300	)	Other, net

Balance Sheet Details (Tables)

3 Months Ended

Apr. 01, 2017

Balance Sheet Details

Inventories

The following shows the details of selected Condensed Consolidated Balance Sheet items (in thousands):

Inventories

	April 1, 2017		December 31, 2016
Work in progress	$	42,493	$	40,755
Finished goods	18,815		18,823
	$	61,308	$	59,578

Debt (Tables)

3 Months Ended

Apr. 01, 2017

Debt

Summary of information about the equity and liability components of the convertible senior notes

The carrying amount of the Notes consisted of the following (in thousands):

	April 1, 2017
Liability component
Principal	$	400,000
Unamortized debt discount	(58,561		)
Unamortized debt issuance costs	(8,937		)
Net carrying amount	$	332,502

Equity component
Net carrying amount	$	57,718

Schedule of components of interest expense

Interest expense related to the Notes was comprised of the following (in thousands):

	Three Months Ended
	April 1, 2017
Contractual interest expense	$	382
Amortization of debt discount	754
Amortization of debt issuance costs	115
	$	1,251

Stockholders' Equity (Tables)

3 Months Ended

Apr. 01, 2017

Stockholders' Equity

Schedule of share repurchase programs

The Board of Directors authorized the following share repurchase programs (in thousands):

Program Authorization Date	Program Termination Date	Program Amount
January 2017	December 2017	$	100,000
August 2015	December 2016	$	100,000

Schedule of components of accumulated other comprehensive income (loss), net of taxes

The components of accumulated other comprehensive income (loss), net of taxes, were as follows (in thousands):

	Unrealized Gain on Cash Flow Hedge			Net Unrealized Losses on Available-For-Sale Securities			Total
Balance at December 31, 2016	$	1,175		$	(683	)	$	492

Other comprehensive income (loss) before reclassifications	—			158			158
Amount reclassified from accumulated other comprehensive income (loss)	(1,175		)	—			(1,175		)
Net change for the period	(1,175		)	158			(1,017		)

Balance at April 1, 2017	$	—		$	(525	)	$	(525	)

Schedule of reclassifications out of accumulated other comprehensive income (loss)

The following table summarizes the effect on net income from reclassifications out of accumulated other comprehensive income (loss) (in thousands):

	Three Months Ended
Reclassification	April 1, 2017			April 2, 2016
Gains (losses) on cash flow hedges to:
Interest expense	$	1,808		$	(66	)

Income tax benefit	(633		)	23

Total reclassifications	$	1,175		$	(43	)

Stock-Based Compensation (Tables)

3 Months Ended

Apr. 01, 2017

Stock-Based Compensation

Schedule of stock-based compensation costs recognized in the Condensed Consolidated Statements of Income

The following table presents details of stock-based compensation costs recognized in the Condensed Consolidated Statements of Income (in thousands):

	Three Months Ended
	April 1, 2017		April 2, 2016
Cost of revenues	$	258	$	266
Research and development	5,246		4,910
Selling, general and administrative	4,982		5,168
	10,486		10,344
Income tax benefit	5,282		2,236
	$	5,204	$	8,108

Significant Accounting Policies (Details)	3 Months Ended	12 Months Ended
Significant Accounting Policies (Details)	Apr. 01, 2017	Dec. 31, 2016
Basis of Presentation and Principles of Consolidation
Length of fiscal year	364 days	364 days
Number of days in each fiscal quarter for 52-week fiscal year	91 days
Low end of range
Basis of Presentation and Principles of Consolidation
Length of fiscal year	364 days
High end of range
Basis of Presentation and Principles of Consolidation
Length of fiscal year	371 days

Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Recent Accounting Pronouncements
Excess tax benefit	$ (1,970)	$ 265
Accounting Standards Update 2016-09 - Compensation-Stock Compensation \| Scenario, Adjustment
Recent Accounting Pronouncements
Excess tax benefit	$ (3,300)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Earnings Per Share
Net income	$ 15,426	$ 5,808
Shares used in computing basic earnings per share (in shares)	42,096	41,629
Effect of dilutive securities:
Stock options and other stock-based awards (in shares)	934	570
Shares used in computing diluted earnings per share (in shares)	43,030	42,199
Earnings per share:
Basic (in dollars per share)	$ 0.37	$ 0.14
Diluted (in dollars per share)	$ 0.36	$ 0.14
Shares excluded from computation of diluted earning per share (in shares)	300	800

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Apr. 01, 2017	Dec. 31, 2016
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	$ 396,327	$ 153,961
Total long-term investments	5,257	5,196
Assets and liabilities measured at fair value on recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	85,090	69,432
Total short-term investments	50,437	12,416
Total assets at fair value	135,527	81,848
Assets and liabilities measured at fair value on recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money market funds
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	85,090	69,432
Assets and liabilities measured at fair value on recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| U.S. government bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	50,437	12,416
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	70,297	11,057
Total short-term investments	345,890	141,545
Derivative instruments		1,808
Other assets, net		1,808
Total assets at fair value	416,187	154,410
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2) \| Certificates of deposit
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	32,183	7,153
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2) \| Municipal bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	6,034	3,904
Total short-term investments	78,555	79,702
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2) \| Corporate bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	1,498
Total short-term investments	108,828	31,036
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2) \| Variable-rate demand notes
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	117,770	16,400
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2) \| Asset-backed securities
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	25,519	8,173
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2) \| Agency bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	7,482
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2) \| Commercial paper
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	30,582
Total short-term investments	6,239	5,233
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2) \| International government bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	1,497	1,001
Assets and liabilities measured at fair value on recurring basis \| Significant Unobservable Inputs (Level 3)
Financial assets and liabilities measured at fair value on a recurring basis
Total long-term investments	5,257	5,196
Total assets at fair value	5,257	5,196
Contingent consideration, noncurrent	3,829
Total liabilities at fair value	3,829
Assets and liabilities measured at fair value on recurring basis \| Significant Unobservable Inputs (Level 3) \| Auction rate securities
Financial assets and liabilities measured at fair value on a recurring basis
Total long-term investments	5,257	5,196
Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	155,387	80,489
Total short-term investments	396,327	153,961
Total long-term investments	5,257	5,196
Derivative instruments		1,808
Other assets, net		1,808
Total assets at fair value	556,971	241,454
Contingent consideration, noncurrent	3,829
Total liabilities at fair value	3,829
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Money market funds
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	85,090	69,432
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Certificates of deposit
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	32,183	7,153
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Municipal bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	6,034	3,904
Total short-term investments	78,555	79,702
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Corporate bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	1,498
Total short-term investments	108,828	31,036
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Variable-rate demand notes
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	117,770	16,400
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| U.S. government bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	50,437	12,416
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Asset-backed securities
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	25,519	8,173
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Agency bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	7,482
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Commercial paper
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	30,582
Total short-term investments	6,239	5,233
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| International government bonds
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	1,497	1,001
Assets and liabilities measured at fair value on recurring basis \| Fair Value \| Auction rate securities
Financial assets and liabilities measured at fair value on a recurring basis
Total long-term investments	$ 5,257	$ 5,196

Fair Value of Financial Instruments - Available-for-sale investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Dec. 31, 2016
Cost
Due in one year or less, Cost	$ 291,314
Due after one year through ten years, Cost	149,197
Due after ten years, Cost	117,270
Total Cost	557,781
Fair Value
Due in one year or less, Fair Value	291,287
Due after one year through ten years, Fair Value	149,157
Due after ten years, Fair Value	116,527
Total Fair Value	556,971
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	134,804	$ 101,480
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	5,257	5,196
Total fair value of available-for-sale securities, continuous loss position	140,061	106,676
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(235)	(288)
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(742)	(804)
Available-for-sale securities, total gross unrealized losses	(977)	(1,092)
Other than temporary impairment losses
Other-than-temporary impairment losses	0
Corporate bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	45,299	18,561
Total fair value of available-for-sale securities, continuous loss position	45,299	18,561
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(145)	(128)
Available-for-sale securities, total gross unrealized losses	(145)	(128)
Municipal bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	38,781	69,379
Total fair value of available-for-sale securities, continuous loss position	38,781	69,379
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(42)	(140)
Available-for-sale securities, total gross unrealized losses	(42)	(140)
U.S. government bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	28,251	10,364
Total fair value of available-for-sale securities, continuous loss position	28,251	10,364
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(23)	(16)
Available-for-sale securities, total gross unrealized losses	(23)	(16)
Asset-backed securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	17,478	3,176
Total fair value of available-for-sale securities, continuous loss position	17,478	3,176
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(22)	(4)
Available-for-sale securities, total gross unrealized losses	(22)	(4)
Auction rate securities
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for twelve months or longer	5,257	5,196
Total fair value of available-for-sale securities, continuous loss position	5,257	5,196
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for 12 months or greater, gross unrealized losses	(742)	(804)
Available-for-sale securities, total gross unrealized losses	(742)	$ (804)
Agency bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	3,498
Total fair value of available-for-sale securities, continuous loss position	3,498
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(1)
Available-for-sale securities, total gross unrealized losses	(1)
International government bonds
Continuous unrealized loss position, Fair Value
Fair value of available-for-sale securities, continuous loss position for less than twelve months	1,497
Total fair value of available-for-sale securities, continuous loss position	1,497
Continuous unrealized loss position, Gross Unrealized Losses
Available-for-sale securities, continuous loss position for less than 12 months, gross unrealized losses	(2)
Available-for-sale securities, total gross unrealized losses	$ (2)

Fair Value of Financial Instruments - Auction rate securities and Contingent consideration (Details) - Significant Unobservable Inputs (Level 3) - Weighted Average - Discounted cash flow	3 Months Ended
	Apr. 01, 2017
Assets and liabilities measured at fair value on recurring basis
Quantitative information for Level 3 Fair Value Measurements Assets
Expected holding period	9 months
Estimated discount rate (as a percent)	12.00%
Auction rate securities
Quantitative information for Level 3 Fair Value Measurements Assets
Estimated yield (as a percent)	0.90%
Expected holding period	10 years
Estimated discount rate (as a percent)	3.56%

Fair Value of Financial Instruments - Assets in Level 3 (Details) - Assets and liabilities measured at fair value on recurring basis - Significant Unobservable Inputs (Level 3) - Auction rate securities $ in Thousands	3 Months Ended
	Apr. 01, 2017 USD ($)
Fair value assets reconciliation of changes
Balance at the beginning of the period	$ 5,196
Gain included in other comprehensive loss	61
Balance at the end of the period	$ 5,257

Fair Value of Financial Instruments - Liabilities in Level 3 (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Dec. 31, 2016
Fair value liabilities reconciliation of changes
Fair value of debt	$ 0	$ 72,500
Assets and liabilities measured at fair value on recurring basis \| Significant Unobservable Inputs (Level 3) \| Contingent consideration
Fair value liabilities reconciliation of changes
Issues	3,829
Balance at the end of the period	3,829
Convertible Senior Notes
Fair value liabilities reconciliation of changes
Fair value of debt	$ 426,300

Derivative Financial Instruments (Details) $ in Millions	Apr. 01, 2017 USD ($)
Cash flow hedges \| Interest rate swaps
Notional amount
Original notional value	$ 72.5

Derivative Financial Instruments - Financial Instrument (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016	Dec. 31, 2016
Derivative financial instrument
Reclassification for (gains) losses included in net income	$ (1,808)	$ 66
Other assets, net
Derivative financial instrument
Fair value of interest rate swap			$ 1,808

Derivative Financial Instruments - Before-tax Effect (Details) $ in Thousands	3 Months Ended
	Apr. 01, 2017 USD ($) contract	Apr. 02, 2016 USD ($) contract
Not Designated as Hedging Instrument \| Foreign currency forward contracts
Derivative Instruments, Gain (Loss)
Number of foreign currency forward contract held \| contract	1	1
Original notional value	$ 4,000	$ 4,800
Not Designated as Hedging Instrument \| Foreign currency forward contracts \| Other income (expense), net
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in Income	(94)	(300)
Cash flow hedges \| Interest rate swaps
Derivative Instruments, Gain (Loss)
Gain (Loss) Recognized in OCI on Derivatives (Effective Portion) during period		(286)
Original notional value	72,500
Cash flow hedges \| Interest rate swaps \| Interest expense
Derivative Instruments, Gain (Loss)
Loss Reclassified from Accumulated OCI into Income (Effective Portion) during period	$ 1,808	$ (66)

Balance Sheet Details (Details) - USD ($) $ in Thousands	Apr. 01, 2017	Dec. 31, 2016
Inventories
Work in progress	$ 42,493	$ 40,755
Finished goods	18,815	18,823
Total inventories	$ 61,308	$ 59,578

Acquisitions (Details) - Zentri $ in Millions	Jan. 20, 2017 USD ($)
Acquisition
Purchase price of acquisition	$ 18.1
Cash consideration	14.3
Earn-Out, fair value	3.8
Potential maximum contingent consideration that could be paid	10.0
Purchase price allocation
Intangible assets	6.7
Goodwill tax deductible	12.5
Other net liabilities	$ 1.1

Debt - Convertible Senior Notes (Details)	Mar. 06, 2017 USD ($) item $ / shares	Apr. 01, 2017 USD ($)
Amended Credit Agreement
Debt
Repayment of debt	$ 72,500,000
1.375% Convertible Senior Notes
Debt
Principal amount of convertible senior notes sold in private placement	$ 400,000,000	$ 400,000,000
Stated interest rate	1.375%
Conversion rate	10.7744
Principal amount of notes	$ 1,000
Initial conversion price \| $ / shares	$ 92.81
Number of trading days within 30 trading day period \| item	20
Number of consecutive trading days	30 days
Minimum amount the sales price of the Company's stock exceeds the conversion price (as a percent)	130.00%
Number of consecutive business days after the 10 consecutive trading day period	5 days
Number of consecutive trading days before the five consecutive business days	10 days
Maximum amount the sales price of the Company's stock exceeds the conversion price (as a percent)	98.00%

Debt - Carrying amount of notes and interest expense (Details) - 1.375% Convertible Senior Notes - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Mar. 06, 2017
Debt
Total Debt issuance costs		$ 10,600
Liability component
Principal	$ 400,000	$ 400,000
Unamortized debt discount	(58,561)
Unamortized debt issuance costs	(8,937)
Net carrying amount	332,502
Equity component
Net carrying amount	$ 57,718
Effective interest rate	4.75%
Amortization of debt discount and debt issuance costs	4 years 10 months 24 days
Interest expense related to the Notes
Contractual interest expense	$ 382
Amortization of debt discount	754
Amortization of debt issuance costs	115
Interest Expense, Total	$ 1,251

Debt - Amended Credit Agreement (Details) $ in Millions			3 Months Ended
Debt - Amended Credit Agreement (Details) $ in Millions	Jul. 24, 2015 USD ($)	Jul. 31, 2012 USD ($)	Apr. 01, 2017
Credit Agreement
Debt
Maximum borrowing capacity		$ 230.0
Term of debt instrument		5 years
Amount borrowed under the Amended Credit Agreement	$ 82.5
Revolving Credit Facility
Debt
Maximum borrowing capacity	$ 300.0	$ 130.0
Term of debt instrument	5 years
Sublimit on letters of credit	$ 25.0
Sublimit on swingline loan	10.0
Additional increase in borrowing capacity of the line of credit available at the entity's option	200.0
Amended Credit Agreement
Debt
Repayment of credit facility amount	$ 72.5
Maximum leverage ratio			3.00
Minimum fixed charge coverage ratio			1.25
Revolving credit facility, other than swingline loans \| Federal Funds
Debt
Interest rate added to the base rate (as a percent)			0.50%
Revolving credit facility, other than swingline loans \| Eurodollar base rate
Debt
Interest rate added to the base rate (as a percent)			1.00%
Revolving credit facility, other than swingline loans \| Eurodollar \| Low end of range
Debt
Interest rate added to the base rate (as a percent)			1.25%
Revolving credit facility, other than swingline loans \| Eurodollar \| High end of range
Debt
Interest rate added to the base rate (as a percent)			2.00%
Term loan facility, revolving credit facility, swingline and other loans \| Base rate \| Low end of range
Debt
Interest rate added to the base rate (as a percent)			0.25%
Term loan facility, revolving credit facility, swingline and other loans \| Base rate \| High end of range
Debt
Interest rate added to the base rate (as a percent)			1.00%
Term Loan Facility
Debt
Maximum borrowing capacity		$ 100.0

Stockholders' Equity - Components of AOCI (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016	Jan. 31, 2017	Aug. 31, 2015
Number of shares of common stock issued	0.5
Program Amount authorized to repurchase			$ 100,000	$ 100,000
Repurchase of common stock (in shares)	0.0	0.4
Repurchase of common stock		$ 18,500
Components of accumulated other comprehensive income (loss), net of taxes
Balance	$ 826,958
Other comprehensive loss	(1,017)	$ (306)
Balance	878,834
Unrealized Gain on Cash Flow Hedge
Components of accumulated other comprehensive income (loss), net of taxes
Balance	1,175
Amount reclassified from accumulated other comprehensive income (loss)	(1,175)
Other comprehensive loss	(1,175)
Net Unrealized Losses on Available-For-Sale Securities
Components of accumulated other comprehensive income (loss), net of taxes
Balance	(683)
Other comprehensive income (loss) before reclassifications	158
Other comprehensive loss	158
Balance	(525)
Accumulated Other Comprehensive Loss
Components of accumulated other comprehensive income (loss), net of taxes
Balance	492
Other comprehensive income (loss) before reclassifications	158
Amount reclassified from accumulated other comprehensive income (loss)	(1,175)
Other comprehensive loss	(1,017)
Balance	$ (525)

Stockholders' Equity - Reclassified from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Amounts Reclassified from AOCI
Income tax benefit	$ 1,970	$ (265)
Net income	15,426	5,808
Reclassifications From Accumulated Other Comprehensive Income (Loss)
Amounts Reclassified from AOCI
Income tax benefit	(633)	23
Net income	1,175	(43)
Unrealized Gain on Cash Flow Hedge \| Reclassifications From Accumulated Other Comprehensive Income (Loss)
Amounts Reclassified from AOCI
Interest expense	$ 1,808	$ (66)

Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
Stock-Based Compensation (Details) - USD ($) $ in Thousands	Apr. 01, 2017	Apr. 02, 2016
Stock-based compensation costs
Share based compensation cost	$ 10,486	$ 10,344
Income tax benefit	5,282	2,236
Share based compensation cost after tax	5,204	8,108
Total unrecognized compensation costs related to awards	$ 88,800
Weighted-average period of recognition of unrecognized compensation costs	2 years 6 months
Cost of revenues
Stock-based compensation costs
Share based compensation cost	$ 258	266
Research and development
Stock-based compensation costs
Share based compensation cost	5,246	4,910
Selling, general and administrative
Stock-based compensation costs
Share based compensation cost	$ 4,982	$ 5,168

Commitments and Contingencies (Details) - patent	Jul. 16, 2014	Jan. 21, 2014
Cresta Technology
Patent Litigation
Number of patents allegedly infringed	6	3

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Mr. Bock
Related Party Transaction
Lease payments	$ 0.9	$ 0.8

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Apr. 01, 2017	Apr. 02, 2016
Income Taxes
Income tax benefit	$ 1,970	$ (265)
Effective income tax rate reconciliation
Effective income tax rate (as a percent)	(14.60%)	4.40%
Components of deferred taxes
Gross unrecognized tax benefits	$ 3,600
Gross unrecognized tax benefits which would affect the effective tax rate if recognized	2,200
Amount of estimated decrease in unrecognized tax benefits	$ 1,900