FormFactor (FORM) 10-Q 28 Oct 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 26, 2015	Oct. 27, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	FORMFACTOR INC.
Entity Central Index Key	1,039,399
Current Fiscal Year End Date	--12-26
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 26, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		58,160,215

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Income Statement [Abstract]
Revenues	$ 65,862	$ 73,933	$ 210,576	$ 197,245
Cost of revenues	47,407	49,791	146,028	140,754
Gross profit	18,455	24,142	64,548	56,491
Operating expenses:
Research and development	10,645	11,198	32,947	32,019
Selling, general and administrative	11,108	13,309	34,373	38,754
Restructuring charges, net	59	28	562	2,084
Impairment of long-lived assets	0	86	8	829
Total operating expenses	21,812	24,621	67,890	73,686
Operating loss	(3,357)	(479)	(3,342)	(17,195)
Interest income, net	65	75	213	233
Other income (expense), net	982	228	2,584	6
Loss before income taxes	(2,310)	(176)	(545)	(16,956)
Provision for income taxes	215	101	359	358
Net loss	$ (2,525)	$ (277)	$ (904)	$ (17,314)
Net loss per share:
Basic and Diluted (In dollars per share)	$ (0.04)	$ 0	$ (0.02)	$ (0.31)
Weighted-average number of shares used in per share calculations:
Basic and Diluted (In shares)	58,209	56,297	57,757	55,720

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (2,525)	$ (277)	$ (904)	$ (17,314)
Other comprehensive loss, net of tax:
Foreign currency translation adjustments	(161)	(814)	(409)	(376)
Unrealized gains on available-for-sale marketable securities	(7)	1	4	25
Other comprehensive loss, net of tax	(168)	(813)	(405)	(351)
Comprehensive loss	$ (2,693)	$ (1,090)	$ (1,309)	$ (17,665)

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Current assets:
Cash and cash equivalents	$ 142,185	$ 113,940
Marketable securities	41,654	49,897
Accounts receivable, net	36,682	45,152
Inventories, net	27,000	25,548
Deferred tax assets	2,029	2,036
Refundable income taxes	0	782
Prepaid expenses and other current assets	6,501	6,919
Total current assets	256,051	244,274
Restricted cash	435	435
Property, plant and equipment, net	23,821	25,498
Goodwill	30,731	30,731
Intangibles, net	28,869	38,689
Deferred tax assets	3,440	3,466
Other assets	865	1,150
Total assets	344,212	344,243
Current liabilities:
Accounts payable	21,159	20,274
Accrued liabilities	18,492	21,217
Income taxes payable	166	68
Deferred revenue	4,215	6,303
Total current liabilities	44,032	47,862
Long-term income taxes payable	1,034	1,094
Deferred tax liabilities	2,208	2,208
Deferred rent and other liabilities	3,404	3,643
Total liabilities	$ 50,678	$ 54,807
Commitments and contingencies (Note 16)
Stockholders’ equity:
Preferred stock, $0.001 par value: 10,000,000 shares authorized; no shares issued and outstanding at June 27, 2015 and December 27, 2014, respectively	$ 0	$ 0
Common stock, $0.001 par value: 250,000,000 shares authorized; 58,368,157 and 56,518,428 shares issued and outstanding at June 27, 2015 and December 27, 2014, respectively	58	57
Additional paid-in capital	717,082	711,676
Accumulated other comprehensive loss	(2,166)	(1,761)
Accumulated deficit	(421,440)	(420,536)
Total stockholders’ equity	293,534	289,436
Total liabilities and stockholders’ equity	$ 344,212	$ 344,243

Condensed Consolidated Balance5

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 26, 2015	Dec. 27, 2014
Stockholders' Equity:
Preferred stock, par value, in dollars per share	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value, in dollars per share	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	58,160,215	56,518,428
Common stock, shares outstanding	58,160,215	56,518,428

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014
Cash flows from operating activities:
Net loss	$ (904)	$ (17,314)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	17,875	24,155
(Accretion) amortization of discount on investments	(1)	199
Stock-based compensation expense	8,515	10,023
Deferred income tax provision (benefit)	7	(44)
(Recovery) provision for doubtful accounts receivable	(11)	1
Provision for excess and obsolete inventories	4,886	5,530
(Gain) loss on disposal, write-off and sale of long-lived assets	(1,009)	41
Impairment of long-lived assets	8	829
Non-cash restructuring	500	600
Foreign currency transaction (gains) losses	(191)	880
Changes in assets and liabilities:
Accounts receivable	8,327	(17,918)
Inventories	(6,337)	(10,725)
Prepaid expenses and other current assets	143	(1,087)
Refundable income taxes	782	0
Other assets	250	16
Accounts payable	1,242	5,998
Accrued liabilities	(2,906)	5,484
Income tax payable	36	160
Deferred rent and other liabilities	79	151
Deferred revenues	(2,090)	(1,564)
Net cash provided by operating activities	29,201	5,415
Cash flows from investing activities:
Acquisition of property, plant and equipment	(6,644)	(4,539)
Proceeds from sale of intellectual property and plant and equipment	1,200	820
Proceeds from sale of subsidiary	44	85
Purchases of marketable securities	(41,253)	(31,693)
Proceeds from maturities of marketable securities	49,500	58,323
Net cash provided by investing activities	2,847	22,996
Cash flows from financing activities:
Proceeds from issuances of common stock	3,418	2,813
Purchase and retirement of common stock	(6,996)	0
Payments made on capital leases	0	(271)
Net cash (used in) provided by financing activities	(3,578)	2,542
Effect of exchange rate changes on cash and cash equivalents	(225)	(885)
Net increase in cash and cash equivalents	28,245	30,068
Cash and cash equivalents, beginning of period	113,940	59,196
Cash and cash equivalents, end of period	142,185	89,264
Supplemental cash flow disclosures:
Changes in accounts payable and accrued liabilities related to property, plant and equipment purchases	(262)	(1,105)
Income and property taxes (refunded) paid, net	$ (94)	$ 789

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 26, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies Basis of presentation. The accompanying unaudited condensed consolidated interim financial statements of FormFactor, Inc. and our subsidiaries have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the instructions to Form 10-Q and Article 10 of Regulation S-X of the U.S. Securities and Exchange Commission (the “SEC”). Our interim financial statements do not include all of the information and footnotes required by generally accepted accounting principles for annual financial statements. In the opinion of management, all adjustments (consisting only of normal recurring adjustments) considered necessary to fairly present our financial position, results of operations and cash flows have been included. Operating results for the three and nine months ended September 26, 2015 are not necessarily indicative of the results that may be expected for the year ending December 26, 2015 , or for any other period. The balance sheet at December 27, 2014 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by GAAP for complete financial statements. The condensed consolidated financial statements include our accounts as well as those of our wholly-owned subsidiaries after elimination of all inter-company balances and transactions. The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in our condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates, and may result in material effects on our consolidated operating results and financial position. These financial statements and notes should be read with the consolidated financial statements and notes for the year ended December 27, 2014 included in our Annual Report on Form 10-K filed with the SEC on March 6, 2015. Fiscal year. We operate on a 52 / 53 week fiscal year, whereby the fiscal year ends on the last Saturday of December. Fiscal 2015 and 2014 each contain 52 weeks and the three and nine months ended September 26, 2015 and September 27, 2014 each contained 13 and 39 weeks, respectively. Fiscal 2015 will end on December 26, 2015 . Critical Accounting Policies. Our critical accounting policies have not changed during the three and nine months ended September 26, 2015 from those disclosed in our Annual Report on Form 10-K for the year ended December 27, 2014 .

Concentration of Credit and Oth

Concentration of Credit and Other Risks	9 Months Ended
	Sep. 26, 2015
Risks and Uncertainties [Abstract]
Concentration of Credit and Other Risks	Concentration of Credit and Other Risks Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash equivalents, marketable securities and trade receivables. Our cash equivalents and marketable securities are held in safekeeping by large, credit worthy financial institutions. We invest our excess cash primarily in U.S. banks, government and agency bonds, money market funds and corporate obligations. We have established guidelines relative to credit ratings, diversification and maturities that seek to maintain safety and liquidity. Deposits in these banks may exceed the amounts of insurance provided on such deposits. To date, we have not experienced any losses on our deposits of cash and cash equivalents. We market and sell our products to a narrow base of customers and generally do not require collateral. The following customers accounted for more than 10% of our revenues for the periods indicated: Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Samsung 23.1 % 10.8 % 16.4 % * Intel 18.1 18.9 17.9 18.3 SK hynix 15.6 15.6 15.3 18.0 Micron * 16.6 12.6 14.6 56.8 % 61.9 % 62.2 % 50.9 % * Less than 10% of revenues. At September 26, 2015 , two customers accounted for 28% and 14% of gross accounts receivable. At December 27, 2014 , two customers accounted for approximately 26% and 18% of gross accounts receivable. No other customers accounted for more than 10% of gross accounts receivable at either of these fiscal period ends. We operate in the intensely competitive semiconductor industry, including the Dynamic Random Access Memory, or DRAM, Flash memory, and System-on-Chip, or SoC markets, which have been characterized by price erosion, rapid technological change, short product life cycles and heightened foreign and domestic competition. Significant technological changes in the industry could adversely affect our operating results. Certain components for our wafer probe card products that meet our requirements are available only from a limited number of suppliers. The rapid rate of technological change and the necessity of developing and manufacturing products with short life cycles may intensify our reliance on such suppliers. The inability to obtain components as required, or to develop alternative sources, if and as required in the future, could result in delays or reductions in product shipments, which in turn could have a material adverse effect on our business, financial condition, results of operations or cash flows.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 26, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill recorded from the acquisition of MicroProbe on October 16, 2012 was $30.7 million as of September 26, 2015 and remained unchanged from the amounts recorded as of December 27, 2014 . The Company has not recorded any historical goodwill impairments as of September 26, 2015 . The changes in intangible assets during the nine months ended September 26, 2015 and the net book value of intangible assets as of September 26, 2015 and December 27, 2014 were as follows (in thousands): Intangible Assets, Gross Amount Accumulated Amortization Intangible Assets, Net Weighted Average Useful Life Other Intangible Assets (1) December 27, 2014 Additions/Disposals September 26, 2015 December 27, 2014 Expense, net September 26, 2015 December 27, 2014 September 26, 2015 September 26, 2015 Existing developed technologies (2) $ 45,300 $ 2,400 $ 47,700 $ 29,097 $ 7,830 $ 36,927 $ 16,203 $ 10,773 2.0 Trade name 4,388 — 4,388 970 328 1,298 3,418 3,090 7.0 Customer relationships 17,000 — 17,000 4,832 1,662 6,494 12,168 10,506 5.0 Total finite-lived intangible assets 66,688 2,400 69,088 34,899 9,820 44,719 31,789 24,369 In-process research and development 6,900 (2,400 ) 4,500 — — — 6,900 4,500 Total intangible assets $ 73,588 $ — $ 73,588 $ 34,899 $ 9,820 $ 44,719 $ 38,689 $ 28,869 (1 ) Excludes fully amortized intangible assets (2 ) As of September 26, 2015, we excluded approximately $5.9 million of fully amortized existing developed technology intangible assets from gross intangible assets and accumulated amortization due to the sale of these intangible assets to MarTek Inc. These intangible assets were fully amortized as of December 27, 2014 but were in use until their sale to MarTek Inc. Refer to Note 16 to the Condensed Consolidated Financial Statements- Commitments and Contingencies , for further details. During the nine months ended September 26, 2015 , a purchased in-process research and development ("IPR&D") project with a carrying value of $2.4 million was completed and reclassified as a finite-lived intangible asset, and is currently being amortized over its estimated useful life. The remaining IPR&D asset is classified as an indefinite lived intangible asset that is not currently subject to amortization but is reviewed for impairment annually or whenever events or changes in circumstances indicate that the carrying value of such asset may not be recoverable. The IPR&D asset will be subject to amortization upon completion of its respective research project and at the start of commercialization. The fair value assigned to the IPR&D asset was determined using the income approach based on estimates and judgments regarding risks inherent in the development process, including the likelihood of achieving technological success and market acceptance. If the IPR&D project is abandoned, the acquired technology attributable to the project will be expensed in the Condensed Consolidated Statements of Operations. For the three and nine months ended September 26, 2015 , amortization expense of $2.7 million and $0.7 million , and $7.8 million and $2.0 million , respectively, was included in cost of revenues and selling, general and administrative expenses, respectively. For the three and nine months ended September 27, 2014 , amortization expense of $4.4 million and $0.7 million , and $13.2 million and $2.0 million , respectively, was included in cost of revenues and selling, general and administrative expenses, respectively. Based on the carrying values of the finite-lived intangible assets recorded as of September 26, 2015 and assuming no subsequent additions to or impairment of the underlying assets, the remaining estimated annual amortization expense is expected to be as follows (in thousands): Fiscal Year Amount 2015 $ 3,317 2016 9,511 2017 3,314 2018 2,949 2019 2,447 and thereafter 2,831 Total $ 24,369

Restructuring Charges

Restructuring Charges	9 Months Ended
	Sep. 26, 2015
Restructuring and Related Activities [Abstract]
Restructuring Charges	Restructuring Charges Restructuring charges include costs related to employee termination benefits, cost of long-lived assets abandoned or impaired, as well as contract termination costs. Restructuring charges are reflected separately as "Restructuring charges, net" in the Condensed Consolidated Statements of Operations. A summary of the actions we have taken during the three and nine months ended September 26, 2015 and September 27, 2014 , the purposes of which were to improve operating efficiency, streamline and simplify our operations and reduce our operating costs, are discussed below. 2015 Restructuring Activities During the three months ended September 26, 2015 , restructuring charges recorded were insignificant. During the nine months ended September 26, 2015 , we recorded stock-based compensation expense of approximately $0.5 million relating to the modification of certain equity-based awards of a full-time employee who was notified of his termination during the fourth quarter of fiscal 2014. The severance terms relating to the modification of his equity-based awards were finalized during the first quarter of fiscal 2015 . 2014 Restructuring Activities On January 27, 2014, we announced a global organizational restructuring and cost reduction plan. As part of the plan, we eliminated 52 full-time employees. In addition, we reduced our temporary workforce by 9 positions. We recorded $2.0 million of restructuring charges during the first quarter of fiscal 2014, which was comprised of $1.4 million in severance and related benefits and $0.6 million in impairment charges for certain equipment that would no longer be utilized. During the three months ended June 28, 2014, we eliminated an additional 2 full-time employees and recorded $59 thousand in severance charges. During the three months ended September 27, 2014 , we eliminated an additional full-time position and recorded $28 thousand in severance charges. The activities comprising these restructuring activities and the related cash payments were substantially completed and paid by September 27, 2014 . The activities in the restructuring accrual for the nine months ended September 26, 2015 were as follows (in thousands): Employee Severance and Benefits Stock-based Compensation Total Accrual at December 27, 2014 $ 584 $ — $ 584 Restructuring charges 59 500 559 Cash payments (618 ) — (618 ) Adjustment to restructuring charges 3 — 3 Non-cash settlement — (500 ) (500 ) Accrual at September 26, 2015 $ 28 $ — $ 28 The activities in the restructuring accrual for the nine months ended September 27, 2014 were as follows (in thousands): Employee Severance and Benefits Property and Equipment Impairment Total Accrual at December 28, 2013 $ 138 $ — $ 138 Restructuring charges 1,484 600 2,084 Cash payments (1,592 ) — (1,592 ) Asset impairments — (600 ) (600 ) Non-cash settlements (2 ) — (2 ) Accrual at September 27, 2014 $ 28 $ — $ 28

Fair Value

Fair Value	9 Months Ended
	Sep. 26, 2015
Fair Value Disclosures [Abstract]
Fair Value	Fair Value Assets Measured at Fair Value on a Recurring Basis We measure and report certain assets and liabilities at fair value on a recurring basis, including money market funds, U.S. Treasury securities, agency securities and foreign currency derivatives (see Note 17 to the Condensed Consolidated Financial Statements - Derivative Financial Instruments , for a discussion of fair value of foreign currency derivatives). Assets measured at fair value on a recurring basis as of September 26, 2015 were as follows (in thousands): Level 1 Level 2 Total Assets: Cash equivalents Money market funds $ 81,173 $ — $ 81,173 Agency securities (Federal) — 1,500 1,500 Marketable securities U.S. Treasuries — 19,409 19,409 Agency securities (Federal) — 22,245 22,245 Total $ 81,173 $ 43,154 $ 124,327 Assets measured at fair value on a recurring basis as of December 27, 2014 was as follows (in thousands): Level 1 Level 2 Total Assets: Cash equivalents Money market funds $ 65,303 $ — $ 65,303 Marketable securities U.S. Treasuries — 42,395 42,395 Agency securities (Federal) — 7,502 7,502 Total $ 65,303 $ 49,897 $ 115,200 The Level 1 assets consist of our money market fund deposits. The Level 2 assets consist of our available-for-sale investment portfolio, which are valued utilizing a market approach. Our investments are priced by pricing vendors who provided observable inputs for their pricing without applying significant judgment. Broker pricing is used mainly when a quoted price is not available, the investment is not priced by our pricing vendors or when a broker price is more reflective of fair values in the market in which the investment trades. Our broker-priced investments are labeled as Level 2 investments because fair values of these investments are based on similar assets without applying significant judgments. In addition, all of our investments have a sufficient level of trading volume to demonstrate that the fair values used are appropriate for these investments. We did not have any transfers of assets measured at fair value on a recurring basis to or from Level 1 and Level 2 during each of the three and nine months ended September 26, 2015 and September 27, 2014 . Assets Measured at Fair Value on a Non-Recurring Basis We measure and report goodwill and intangible assets at fair value on a non-recurring basis if we determine these assets to be impaired. Refer to Note 3 to the Condensed Consolidated Financial Statements- Goodwill and Intangible Assets , for further details. There were no assets measured at fair value on a nonrecurring basis during the three and nine months ended September 26, 2015 and September 27, 2014 .

Marketable Securities

Marketable Securities	9 Months Ended
	Sep. 26, 2015
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities We classify our marketable securities as available-for-sale. All marketable securities represent the investment of funds available for current operations, notwithstanding their contractual maturities. Such marketable securities are recorded at fair value and unrealized gains and losses are recorded in accumulated other comprehensive income until realized. Marketable securities at September 26, 2015 consisted of the following (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasuries $ 19,396 $ 13 $ — $ 19,409 Agency securities (Federal) 22,245 — — 22,245 $ 41,641 $ 13 $ — $ 41,654 Marketable securities at December 27, 2014 consisted of the following (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasuries $ 42,386 $ 13 $ (4 ) $ 42,395 Agency securities (Federal) 7,502 — — 7,502 $ 49,888 $ 13 $ (4 ) $ 49,897 The marketable securities with gross unrealized losses have been in a loss position for less than twelve months as of September 26, 2015 and December 27, 2014 , respectively. When evaluating the investments for other-than-temporary impairment, we review factors such as the length of time and extent to which fair value has been below the amortized cost basis, current market liquidity, interest rate risk, financial condition of the issuer, and credit rating downgrades. We believe that the unrealized losses are not other-than-temporary. We do not have a foreseeable need to liquidate the portfolio and anticipate recovering the full cost of the securities either as market conditions improve or as the securities mature. Contractual maturities of marketable securities as of September 26, 2015 were as follows (in thousands): Amortized Cost Fair Value Due in one year or less $ 41,641 $ 41,654 Due after one year to five years — — $ 41,641 $ 41,654 There were no realized gains and losses on sales and maturities of marketable securities during the three and nine months ended September 26, 2015 and September 27, 2014 , respectively.

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts	9 Months Ended
	Sep. 26, 2015
Receivables [Abstract]
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts A reconciliation of the changes in our allowance for doubtful accounts receivable for the nine months ended September 26, 2015 and September 27, 2014 , respectively, is as follows (in thousands): September 26, September 27, Balance at beginning of period $ 266 $ 265 Additions — 5 Reductions (11 ) (4 ) Balance at end of period $ 255 $ 266

Inventories

Inventories	9 Months Ended
	Sep. 26, 2015
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of the following (in thousands): September 26, December 27, Raw materials $ 12,283 $ 10,646 Work-in-progress 13,029 12,813 Finished goods 1,688 2,089 $ 27,000 $ 25,548

Warranty

Warranty	9 Months Ended
	Sep. 26, 2015
Product Warranties Disclosures [Abstract]
Warranty	Warranty A reconciliation of the changes in our warranty liability for the nine months ended September 26, 2015 and September 27, 2014 , respectively, is as follows (in thousands): September 26, September 27, Balance at beginning of period $ 1,592 $ 691 Accruals 1,855 1,932 Settlements (2,284 ) (1,594 ) Balance at the end of period $ 1,163 $ 1,029

Long-lived Assets

Long-lived Assets	9 Months Ended
	Sep. 26, 2015
Property, Plant and Equipment [Abstract]
Long-lived Assets	Long-lived Assets Impairment of long-lived assets During the nine months ended September 26, 2015 , long-lived asset impairment charges recorded were insignificant. During the nine months ended September 27, 2014 , we recorded $0.8 million of impairments related to manufacturing assets we no longer utilized. These charges were included in "Impairment of long-lived assets" in the Condensed Consolidated Statements of Operations in their respective periods. During the three months ended September 26, 2015 , we ceased to use fully depreciated assets with an acquired cost of $0.2 million. Long-lived Assets Property, plant and equipment consisted of the following (in thousands): September 26, December 27, Machinery and equipment $ 149,948 $ 145,995 Computer equipment and software 28,838 28,953 Furniture and fixtures 5,396 5,402 Leasehold improvements 67,090 66,821 Sub total 251,272 247,171 Less: accumulated depreciation and amortization (230,433 ) (224,135 ) Net long-lived assets 20,839 23,036 Construction-in-progress 2,982 2,462 Total $ 23,821 $ 25,498 Assets held for sale There were no assets held for sale as of September 26, 2015 . During the nine months ended September 27, 2014 , we reclassified $0.6 million of building and $0.5 million of machinery and equipment from "Property, plant and equipment, net" to "Prepaid expenses and other current assets" in our balance sheet as these assets were identified as held for sale. The sale of the building closed during the third quarter of fiscal 2014 and we recorded a gain of $0.2 million on the sale during the third quarter of fiscal 2014. Refer to Note 3 to the Condensed Consolidated Financial Statements - Goodwill and Intangible Assets for further details relating to our intangible long-lived assets.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 26, 2015
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Accumulated other comprehensive loss includes foreign currency translation adjustments and unrealized losses on available-for-sale securities, net of tax, the impact of which has been excluded from earnings and reflected as components of stockholders' equity as shown below (in thousands): September 26, December 27, Unrealized loss on marketable securities, net of tax of $428 at September 26, 2015 and December 27, 2014, respectively $ (415 ) $ (419 ) Cumulative translation adjustments (1,751 ) (1,342 ) Accumulated other comprehensive loss $ (2,166 ) $ (1,761 )

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 26, 2015
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock Repurchase Program On April 16, 2015, our Board of Directors authorized a program to repurchase up to $25.0 million of outstanding common stock. Under the authorized stock repurchase program, we may repurchase shares from time-to-time on the open market. The pace of repurchase activity will depend on levels of cash generation, current stock price and other factors. The stock repurchase program was announced on April 16, 2015 and expires on April 15, 2016. The program may be modified or discontinued at any time. During the three months ended September 26, 2015 , under this repurchase authorization, we repurchased and retired 472,800 shares of common stock for approximately $3.5 million . During the nine months ended September 26, 2015 , under this repurchase authorization, we repurchased 873,162 shares of common stock for approximately $7.0 million . Repurchased shares are retired upon the settlement of the related trade transactions. Our policy related to repurchases of our common stock is to charge the excess of cost over par value to additional paid-in capital. All repurchases were made in compliance with Rule 10b-18 under the Securities Exchange Act of 1934, as amended. Restricted Stock Units Restricted stock unit (RSU) activity under our equity incentive plan during the nine months ended September 26, 2015 is set forth below: Units Weighted Average Grant Date Fair Value Restricted stock units at December 27, 2014 3,250,046 $ 6.07 Awards granted 1,507,750 8.66 Awards vested (1,924,849 ) 6.04 Awards canceled (169,019 ) 6.57 Restricted stock units at September 26, 2015 2,663,928 $ 7.52 On May 28, 2015, we issued 195,000 RSUs to seven senior executives of our company that will vest based on certain market performance criteria. The performance criteria are based on a metric called our Total Shareholder Return (TSR) for the period from April 1, 2015 to March 31, 2017 relative to the TSR of the companies identified as being part of the S&P Semiconductor Select Industry Index (FormFactor peer companies), as of April 1, 2015. The total stock-based compensation cost of approximately $1.5 million will be recognized ratably over the requisite service period. On May 5, 2014, we issued 350,000 RSUs to seven senior executives of our company that will vest based on certain market performance criteria. The performance criteria are based on our TSR for the period from April 1, 2014 to March 31, 2016 relative to the TSR of the companies identified as being part of the S&P Semiconductor Select Industry Index (FormFactor peer companies), as of April 1, 2014. The total stock-based compensation cost of approximately $1.8 million will be recognized ratably over the requisite service period. On May 6, 2013, we issued 355,000 RSUs to seven senior executives and one non-executive of our company that would vest based on certain market performance criteria. The performance criteria were based on our TSR for the period from April 1, 2013 to March 31, 2015 relative to the TSR of the companies identified as being part of the S&P Semiconductor Select Industry Index (FormFactor peer companies), as of April 1, 2013. On April 8, 2015, upon the review of the market performance criteria, our Compensation Committee certified a total earn out of 443,750 RSUs which immediately vested as of that date. The total fair value of RSUs vested during the three months ended September 26, 2015 was insignificant. The total fair value of RSUs vested during the nine months ended September 26, 2015 was $17.5 million . The total fair value of RSUs vested during the three and nine months ended September 27, 2014 was $0.2 million and $7.3 million , respectively. Stock Options During the nine months ended September 26, 2015 , we granted 450,000 stock options to our Chief Executive Officer with a grant-date fair value of approximately $1.7 million which will be recognized as stock compensation expense ratably over the service period. T he following weighted average assumptions were used in the estimated grant-date fair value calculations using the Black-Scholes option pricing model: Stock Options: Dividend yield — % Expected volatility 47.5 % Risk-free interest rate 1.57 % Expected term (in years) 5.52 During the nine months ended September 27, 2014 , we did not grant any stock options.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 26, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation We account for all stock-based compensation to employees and directors, including grants of RSUs and stock options, as stock-based compensation costs based on the fair value measured as of the date of grant. These costs are recognized as an expense in the Condensed Consolidated Statements of Operations over the requisite service period. The table below shows stock-based compensation charges included in the Condensed Consolidated Statements of Operations (in thousands): Three Months Ended Nine Months Ended September 26, September 27, September 26, September 27, Stock-based compensation included in: Cost of revenues $ 756 $ 700 $ 1,941 $ 1,855 Research and development 973 1,077 2,544 2,638 Selling, general and administrative 1,371 2,157 4,030 5,530 Total stock-based compensation 3,100 3,934 8,515 10,023 Tax effect of stock-based compensation — — — — Total stock-based compensation, net of tax $ 3,100 $ 3,934 $ 8,515 $ 10,023 During the nine months ended September 26, 2015 , we recorded stock-based compensation expense of approximately $0.5 million relating to a full-time employee who was impacted by our restructuring activities. Hence, we classified this stock-based compensation expense as a restructuring expense. The table above does not include this expense. Refer to Note 4 to the Condensed Consolidated Financial Statements - Restructuring Charges for further details. Employee Stock Purchase Plan Under our 2012 Employee Stock Purchase Plan ("ESPP"), the offering periods are 12 months commencing on February 1 of each calendar year and ending on January 31 of the subsequent calendar year, and a six month fixed offering period commencing on August 1 of each calendar year and ending on January 31 of the subsequent calendar year. The 12 month offering period consists of two six month purchase periods and the six month offering period consists of one six month purchase period. The price of the common stock purchased is 85% of the lesser of the fair market value of the common stock on the first day of the applicable offering period or the last day of each purchase period. During the three months ended September 26, 2015 and September 27, 2014 , we issued 262,788 and 265,467 ESPP shares, respectively. During the nine months ended September 26, 2015 and September 27, 2014 , we issued 565,493 and 586,386 ESPP shares, respectively. The following weighted-average assumptions were used in estimating the fair value of employees' purchase rights under our approved employee stock purchase plans: Three Months Ended Nine Months Ended September 26, September 27, September 26, September 27, ESPP: Dividend yield — % — % — % — % Expected volatility 52.2 % 41.6 % 52.1 % 41.9 % Risk-free interest rate 0.14 % 0.09 % 0.10 % 0.09 % Expected term (in years) 0.81 0.81 0.66 0.66 Unrecognized Compensation Costs At September 26, 2015 , the unrecognized stock-based compensation, adjusted for estimated forfeitures, was as follows (in thousands): Unrecognized Expense Average Expected Recognition Period in years Stock options $ 1,457 3.36 Restricted stock units 14,309 2.09 Employee stock purchase plan 463 0.35 Total unrecognized stock-based compensation expense $ 16,229

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 26, 2015
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share Basic net loss per share is computed by dividing net loss by the weighted-average number of common shares outstanding for the period. Diluted net loss per share for the three and nine months ended September 26, 2015 and September 27, 2014 , respectively, was computed by dividing net loss by the weighted-average number of common shares outstanding for the period as the inclusion of any common stock equivalents would have been anti-dilutive. A reconciliation of the numerator and denominator used in the calculation of basic and diluted net loss per share is as follows (in thousands): Three Months Ended Nine Months Ended September 26, September 27, September 26, September 27, Numerator: Net loss used in computing basic and diluted net loss per share $ (2,525 ) $ (277 ) $ (904 ) $ (17,314 ) Denominator: Weighted-average shares used in computing basic net loss per share 58,209 56,297 57,757 55,720 Add potentially dilutive securities — — — — Weighted-average shares used in computing basic and diluted net loss per share 58,209 56,297 57,757 55,720 The following table sets forth the weighted-average number of all potentially dilutive securities excluded from the computation in the table above because their effect would have been anti-dilutive (in thousands): Three Months Ended Nine Months Ended September 26, September 27, September 26, September 27, Options to purchase common stock 2,710 2,675 2,380 2,981 Restricted stock units 1,717 — 1,550 1 Employee stock purchase plan — 20 30 1 Total potentially dilutive securities 4,427 2,695 3,960 2,983

Income Taxes

Income Taxes	9 Months Ended
	Sep. 26, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recorded an income tax provision of $0.2 million and $0.4 million for the three and nine months ended September 26, 2015 and $0.1 million and $0.4 million for the three and nine months ended September 27, 2014 , respectively. Income tax provisions reflect the tax provision on our operations in the foreign and U.S jurisdictions offset by tax benefit from lapsing of statute of limitations in foreign jurisdictions. We continue to maintain a valuation allowance for our U.S. Federal and State deferred tax assets.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 26, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Contractual and purchase obligations We lease facilities under non-cancellable operating leases with various expiration dates through 2021. The facilities generally require us to pay property taxes, insurance and maintenance costs. Further, several lease agreements contain rent escalation clauses or rent holidays. For purposes of recognizing minimum rental expenses on a straight-line basis over the terms of the leases, we use the date of initial possession to begin amortization. We have the option to extend or renew most of our leases, which may increase the future minimum lease commitments. Purchase obligations are primarily for purchases of inventory and manufacturing related service contracts. Purchase obligations are defined as agreements that are enforceable and legally binding and that specify all significant terms, including: fixed or minimum quantities to be purchased; fixed, minimum or variable price provisions; and the approximate timing of the transaction. Timing of payments and actual amounts paid may be different depending on the time of receipt of goods or services or changes to agreed-upon amounts for some obligations. Our lease and purchase obligations have not materially changed as of September 26, 2015 from those disclosed in our Annual Report on Form 10-K for the year ended December 27, 2014 . Environmental Matters We are subject to U.S. Federal, State and local, and foreign governmental laws and regulations relating to the protection of the environment, including those governing the discharge of pollutants into the air and water, the management and disposal of hazardous substances and wastes, the clean-up of contaminated sites and the maintenance of a safe workplace. We believe that we comply in all material respects with the environmental laws and regulations that apply to us, including those of the California Department of Toxic Substances Control, the Bay Area Air Quality Management District, the City of Livermore Water Resources Division, County of Santa Clara Department of Environmental Health, County of San Diego Hazardous Materials Division and Encino Water District, and the California Division of Occupational Safety and Health. We did not receive any notices of violations of environmental laws and regulations during the nine months ended September 26, 2015 , or in our fiscal 2014. We do not believe that any loss from existing environmental remediation liabilities would have a material impact on our financial condition. While we believe that we are in compliance in all material respects with the environmental laws and regulations that apply to us, in the future, we may receive environmental violation notices, and if received, final resolution of the violations identified by these notices could harm our operations, which may adversely impact our operating results and cash flows. New laws and regulations, amended enforcement practices around existing laws and regulations, the discovery of previously unknown contamination at our or others' sites or the imposition of new cleanup requirements could also harm our operations, thereby adversely impacting our operating results and cash flows. Indemnification Arrangements We have entered, and may from time to time in the ordinary course of our business enter, into contractual arrangements with third parties that include indemnification obligations. Under these contractual arrangements, we have agreed to defend, indemnify and/or hold the third party harmless from and against certain liabilities. These arrangements include indemnities in favor of customers in the event that our products or services infringe a third party's intellectual property or cause property or other damages and indemnities in favor of our lessors in connection with facility leasehold liabilities that we may cause. In addition, we have entered into indemnification agreements with our directors and certain of our officers, and our bylaws contain indemnification obligations in favor of our directors, officers and agents. These indemnity arrangements may limit the type of the claim, the total amount that we can be required to be paid in connection with the indemnification obligation and the time within which an indemnification claim can be made. The duration of the indemnification obligation may vary, and for most arrangements, survives the agreement term and is indefinite. We believe that substantially all of our indemnity arrangements provide either for limitations on the maximum potential future payments we could be obligated to make, or for limitations on the types of claims and damages we could be obligated to indemnify, or both. However, it is not possible to determine or reasonably estimate the maximum potential amount of future payments under these indemnification obligations due to the varying terms of such obligations, a lack of history of prior indemnification claims, the unique facts and circumstances involved in each particular contractual arrangement and in each potential future claim for indemnification, and the contingency of any potential liabilities upon the occurrence of events that are not reasonably determinable. We have not had any material requests for indemnification under these arrangements. Our management believes that any liability for these indemnity arrangements would not be material to our accompanying consolidated financial statements. We have not recorded any liabilities for these indemnification arrangements on our consolidated balance sheet as of September 26, 2015 . Legal Matters From time to time, we may be subject to legal proceedings and claims in the ordinary course of business. For the nine months ended September 26, 2015 , we were not involved in any material legal proceedings. We identify below in "Other Litigation", a proceeding filed in fiscal 2013, which, if not resolved amicably, either (i) includes allegations that could potentially result in a material legal proceeding, or (ii) the cost to defend the allegations through trial could be material. In the future we may become a party to additional legal proceedings that may require us to spend significant resources, including proceedings designed to protect our intellectual property rights. Litigation can be expensive and disruptive to normal business operations. Moreover, the results of legal proceedings are difficult to predict, and the costs incurred in litigation can be substantial, regardless of outcome. Customs and Trade Matters From time to time, we receive communications from certain jurisdictions regarding customs and indirect tax matters such as customs duties and value added taxes. For the nine months ended September 26, 2015 , we did not receive any communications from jurisdictions regarding any material customs duties or indirect tax matters. Intellectual Property Litigation In the ordinary course of business, the Company has been, currently is, and may in the future be, involved in litigation relating to intellectual property, as well as third party initiated patent office proceedings in the United States and foreign patent offices. In March 2014, we filed a lawsuit against MarTek, Inc., a company headquartered in Tempe, Arizona ("MarTek"), asserting breach of contract, copyright infringement and related claims arising out of a licensing agreement we entered into with MarTek for the use by MarTek of certain intellectual property assets (the “IP”) relating to probers that we acquired from the bankruptcy of Electroglas, Inc. MarTek asserted counterclaims against us for breach of contract and related claims regarding that license. On July 13, 2015 (the "closing date"), we entered into an agreement with MarTek under which the parties agreed to dismiss the pending litigation and release each other from any and all claims relating to the license agreement or the IP through the closing date. As part of the agreement, we agreed to sell the IP to MarTek for $2 million , of which $1.2 million was received on July 17, 2015 and the remaining $0.8 million is in the form of a promissory note secured by the IP and scheduled to be repaid by MarTek in two equal tranches on the first and second anniversary of the closing date. During the three months ended September 26, 2015 , we recognized a net gain of approximately $1.0 million (which was classified in our Condensed Consolidated Statement of Operations under Other Income (Expense), net) from the agreement proceeds received on July 17, 2015. Other Litigation In August 2013, a former employee (“Plaintiff”) filed a class action lawsuit against the Company in the Superior Court of California, alleging violations of California’s wage and hour laws and unfair business practices on behalf of himself and all other similarly situated current and former employees at the Company’s Livermore facilities from August 21, 2009, to the present. The Plaintiff's motion to certify a class is pending. Procedurally, the case is still in the early stages of litigation. The Company denies the allegations made by the Plaintiff, and believes it has significant defenses to the claims made in the lawsuit. If the matter is not settled, the Company could incur material attorneys' fees in defending the lawsuit.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 26, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments We operate and sell our products in various global markets. As a result, we are exposed to changes in foreign currency exchange rates. We utilize foreign currency forward contracts to hedge against future movements in foreign exchange rates that affect certain existing foreign currency denominated assets and liabilities. Under this program, our strategy is to have increases or decreases in our foreign currency exposures offset by gains or losses on the foreign currency forward contracts to mitigate the risks and volatility associated with foreign currency transaction gains or losses. We do not use derivative financial instruments for speculative or trading purposes. Our derivative instruments are not designated as hedging instruments. We record the fair value of these contracts as of the end of our reporting period to our Condensed Consolidated Balance Sheet with changes in fair value recorded within “ Other income (expense), net ” in our Condensed Consolidated Statements of Operations for both realized and unrealized gains and losses. The following table provides information about our foreign currency forward contracts outstanding as of September 26, 2015 (in thousands): Currency Contract Position Contract Amount (Local Currency) Contract Amount (U.S. Dollars) Japanese Yen Sell 2,716,297 $ 22,471 Taiwan Dollar Buy (40,006 ) (1,209 ) Korean Won Buy (687,168 ) (581 ) Total USD notional amount of outstanding foreign exchange contracts $ 20,681 The contracts were entered into on September 25, 2015 and matured on October 23, 2015. Our foreign currency contracts are classified within Level 2 of the fair value hierarchy as they are valued using pricing models that utilize observable market inputs. There was no change in the value of these contracts as of September 26, 2015 . Additionally, no gains or losses relating to the outstanding derivative contracts were recorded in the three and nine months ended September 26, 2015 . The location and amount of losses and gains related to non-designated derivative instruments that matured in the three and nine months ended September 26, 2015 and September 27, 2014 in the Condensed Consolidated Statements of Operations are as follows (in thousands): Amount of Loss (Gain) Recognized on Derivatives Three Months Ended Nine Months Ended Derivatives Not Designated as Hedging Instruments Location of Loss (Gain) Recognized on Derivatives September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Foreign exchange forward contracts Other income (expense), net $ (902 ) $ 740 $ (217 ) $ 465

Business Interruption Insurance

Business Interruption Insurance Claim Recovery	9 Months Ended
	Sep. 26, 2015
Extraordinary and Unusual Items [Abstract]
Business Interruption Insurance Claim Recovery	Business Interruption Insurance Claim Recovery During the nine months ended September 26, 2015 , we received approximately $1.5 million as a result of a payment from our insurer arising from a business interruption insurance claim related to a factory fire at a customer during the second half of fiscal 2013. We recorded this cash receipt within “ Other income (expense), net ” in our Condensed Consolidated Statements of Operations.

Basis of Presentation and Sum25

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 26, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Fiscal Period, Policy	Fiscal year. We operate on a 52 / 53 week fiscal year, whereby the fiscal year ends on the last Saturday of December. Fiscal 2015 and 2014 each contain 52 weeks and the three and nine months ended September 26, 2015 and September 27, 2014 each contained 13 and 39 weeks, respectively. Fiscal 2015 will end on December 26, 2015 .
Assets Measured at Fair Value on Recurring Basis	Assets Measured at Fair Value on a Recurring Basis We measure and report certain assets and liabilities at fair value on a recurring basis, including money market funds, U.S. Treasury securities, agency securities and foreign currency derivatives (see Note 17 to the Condensed Consolidated Financial Statements - Derivative Financial Instruments , for a discussion of fair value of foreign currency derivatives)

Concentration of Credit and O26

Concentration of Credit and Other Risks (Tables)	9 Months Ended
	Sep. 26, 2015
Risks and Uncertainties [Abstract]
Schedules of Concentration of Risk, by Risk Factor	We market and sell our products to a narrow base of customers and generally do not require collateral. The following customers accounted for more than 10% of our revenues for the periods indicated: Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Samsung 23.1 % 10.8 % 16.4 % * Intel 18.1 18.9 17.9 18.3 SK hynix 15.6 15.6 15.3 18.0 Micron * 16.6 12.6 14.6 56.8 % 61.9 % 62.2 % 50.9 % * Less than 10% of revenues.

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 26, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The changes in intangible assets during the nine months ended September 26, 2015 and the net book value of intangible assets as of September 26, 2015 and December 27, 2014 were as follows (in thousands): Intangible Assets, Gross Amount Accumulated Amortization Intangible Assets, Net Weighted Average Useful Life Other Intangible Assets (1) December 27, 2014 Additions/Disposals September 26, 2015 December 27, 2014 Expense, net September 26, 2015 December 27, 2014 September 26, 2015 September 26, 2015 Existing developed technologies (2) $ 45,300 $ 2,400 $ 47,700 $ 29,097 $ 7,830 $ 36,927 $ 16,203 $ 10,773 2.0 Trade name 4,388 — 4,388 970 328 1,298 3,418 3,090 7.0 Customer relationships 17,000 — 17,000 4,832 1,662 6,494 12,168 10,506 5.0 Total finite-lived intangible assets 66,688 2,400 69,088 34,899 9,820 44,719 31,789 24,369 In-process research and development 6,900 (2,400 ) 4,500 — — — 6,900 4,500 Total intangible assets $ 73,588 $ — $ 73,588 $ 34,899 $ 9,820 $ 44,719 $ 38,689 $ 28,869 (1 ) Excludes fully amortized intangible assets (2 ) As of September 26, 2015, we excluded approximately $5.9 million of fully amortized existing developed technology intangible assets from gross intangible assets and accumulated amortization due to the sale of these intangible assets to MarTek Inc. These intangible assets were fully amortized as of December 27, 2014 but were in use until their sale to MarTek Inc. Refer to Note 16 to the Condensed Consolidated Financial Statements- Commitments and Contingencies , for further details.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Based on the carrying values of the finite-lived intangible assets recorded as of September 26, 2015 and assuming no subsequent additions to or impairment of the underlying assets, the remaining estimated annual amortization expense is expected to be as follows (in thousands): Fiscal Year Amount 2015 $ 3,317 2016 9,511 2017 3,314 2018 2,949 2019 2,447 and thereafter 2,831 Total $ 24,369

Restructuring Charges (Tables)

Restructuring Charges (Tables)	9 Months Ended
	Sep. 26, 2015
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost	The activities in the restructuring accrual for the nine months ended September 26, 2015 were as follows (in thousands): Employee Severance and Benefits Stock-based Compensation Total Accrual at December 27, 2014 $ 584 $ — $ 584 Restructuring charges 59 500 559 Cash payments (618 ) — (618 ) Adjustment to restructuring charges 3 — 3 Non-cash settlement — (500 ) (500 ) Accrual at September 26, 2015 $ 28 $ — $ 28 The activities in the restructuring accrual for the nine months ended September 27, 2014 were as follows (in thousands): Employee Severance and Benefits Property and Equipment Impairment Total Accrual at December 28, 2013 $ 138 $ — $ 138 Restructuring charges 1,484 600 2,084 Cash payments (1,592 ) — (1,592 ) Asset impairments — (600 ) (600 ) Non-cash settlements (2 ) — (2 ) Accrual at September 27, 2014 $ 28 $ — $ 28

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 26, 2015
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	Assets measured at fair value on a recurring basis as of September 26, 2015 were as follows (in thousands): Level 1 Level 2 Total Assets: Cash equivalents Money market funds $ 81,173 $ — $ 81,173 Agency securities (Federal) — 1,500 1,500 Marketable securities U.S. Treasuries — 19,409 19,409 Agency securities (Federal) — 22,245 22,245 Total $ 81,173 $ 43,154 $ 124,327 Assets measured at fair value on a recurring basis as of December 27, 2014 was as follows (in thousands): Level 1 Level 2 Total Assets: Cash equivalents Money market funds $ 65,303 $ — $ 65,303 Marketable securities U.S. Treasuries — 42,395 42,395 Agency securities (Federal) — 7,502 7,502 Total $ 65,303 $ 49,897 $ 115,200

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
	Sep. 26, 2015
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Securities Reconciliation	Marketable securities at September 26, 2015 consisted of the following (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasuries $ 19,396 $ 13 $ — $ 19,409 Agency securities (Federal) 22,245 — — 22,245 $ 41,641 $ 13 $ — $ 41,654 Marketable securities at December 27, 2014 consisted of the following (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasuries $ 42,386 $ 13 $ (4 ) $ 42,395 Agency securities (Federal) 7,502 — — 7,502 $ 49,888 $ 13 $ (4 ) $ 49,897
Investments Classified by Contractual Maturity Date	Contractual maturities of marketable securities as of September 26, 2015 were as follows (in thousands): Amortized Cost Fair Value Due in one year or less $ 41,641 $ 41,654 Due after one year to five years — — $ 41,641 $ 41,654

Allowance for Doubtful Accoun31

Allowance for Doubtful Accounts (Tables)	9 Months Ended
	Sep. 26, 2015
Receivables [Abstract]
Schedule of Credit Losses for Financing Receivables, Current	A reconciliation of the changes in our allowance for doubtful accounts receivable for the nine months ended September 26, 2015 and September 27, 2014 , respectively, is as follows (in thousands): September 26, September 27, Balance at beginning of period $ 266 $ 265 Additions — 5 Reductions (11 ) (4 ) Balance at end of period $ 255 $ 266

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 26, 2015
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	Inventories consisted of the following (in thousands): September 26, December 27, Raw materials $ 12,283 $ 10,646 Work-in-progress 13,029 12,813 Finished goods 1,688 2,089 $ 27,000 $ 25,548

Warranty (Tables)

Warranty (Tables)	9 Months Ended
	Sep. 26, 2015
Product Warranties Disclosures [Abstract]
Schedule of Product Warranty Liability	A reconciliation of the changes in our warranty liability for the nine months ended September 26, 2015 and September 27, 2014 , respectively, is as follows (in thousands): September 26, September 27, Balance at beginning of period $ 1,592 $ 691 Accruals 1,855 1,932 Settlements (2,284 ) (1,594 ) Balance at the end of period $ 1,163 $ 1,029

Long-lived Assets (Tables)

Long-lived Assets (Tables)	9 Months Ended
	Sep. 26, 2015
Property, Plant and Equipment [Abstract]
Long-lived assets	Property, plant and equipment consisted of the following (in thousands): September 26, December 27, Machinery and equipment $ 149,948 $ 145,995 Computer equipment and software 28,838 28,953 Furniture and fixtures 5,396 5,402 Leasehold improvements 67,090 66,821 Sub total 251,272 247,171 Less: accumulated depreciation and amortization (230,433 ) (224,135 ) Net long-lived assets 20,839 23,036 Construction-in-progress 2,982 2,462 Total $ 23,821 $ 25,498

Accumulated Other Comprehensi35

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 26, 2015
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Loss	Accumulated other comprehensive loss includes foreign currency translation adjustments and unrealized losses on available-for-sale securities, net of tax, the impact of which has been excluded from earnings and reflected as components of stockholders' equity as shown below (in thousands): September 26, December 27, Unrealized loss on marketable securities, net of tax of $428 at September 26, 2015 and December 27, 2014, respectively $ (415 ) $ (419 ) Cumulative translation adjustments (1,751 ) (1,342 ) Accumulated other comprehensive loss $ (2,166 ) $ (1,761 )

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 26, 2015
Stockholders' Equity Note [Abstract]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	Restricted stock unit (RSU) activity under our equity incentive plan during the nine months ended September 26, 2015 is set forth below: Units Weighted Average Grant Date Fair Value Restricted stock units at December 27, 2014 3,250,046 $ 6.07 Awards granted 1,507,750 8.66 Awards vested (1,924,849 ) 6.04 Awards canceled (169,019 ) 6.57 Restricted stock units at September 26, 2015 2,663,928 $ 7.52
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	T he following weighted average assumptions were used in the estimated grant-date fair value calculations using the Black-Scholes option pricing model: Stock Options: Dividend yield — % Expected volatility 47.5 % Risk-free interest rate 1.57 % Expected term (in years) 5.52

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 26, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	The table below shows stock-based compensation charges included in the Condensed Consolidated Statements of Operations (in thousands): Three Months Ended Nine Months Ended September 26, September 27, September 26, September 27, Stock-based compensation included in: Cost of revenues $ 756 $ 700 $ 1,941 $ 1,855 Research and development 973 1,077 2,544 2,638 Selling, general and administrative 1,371 2,157 4,030 5,530 Total stock-based compensation 3,100 3,934 8,515 10,023 Tax effect of stock-based compensation — — — — Total stock-based compensation, net of tax $ 3,100 $ 3,934 $ 8,515 $ 10,023
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions	The following weighted-average assumptions were used in estimating the fair value of employees' purchase rights under our approved employee stock purchase plans: Three Months Ended Nine Months Ended September 26, September 27, September 26, September 27, ESPP: Dividend yield — % — % — % — % Expected volatility 52.2 % 41.6 % 52.1 % 41.9 % Risk-free interest rate 0.14 % 0.09 % 0.10 % 0.09 % Expected term (in years) 0.81 0.81 0.66 0.66
Schedule of Unrecognized Compensation Cost, Nonvested Awards	At September 26, 2015 , the unrecognized stock-based compensation, adjusted for estimated forfeitures, was as follows (in thousands): Unrecognized Expense Average Expected Recognition Period in years Stock options $ 1,457 3.36 Restricted stock units 14,309 2.09 Employee stock purchase plan 463 0.35 Total unrecognized stock-based compensation expense $ 16,229

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 26, 2015
Earnings Per Share [Abstract]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share	A reconciliation of the numerator and denominator used in the calculation of basic and diluted net loss per share is as follows (in thousands): Three Months Ended Nine Months Ended September 26, September 27, September 26, September 27, Numerator: Net loss used in computing basic and diluted net loss per share $ (2,525 ) $ (277 ) $ (904 ) $ (17,314 ) Denominator: Weighted-average shares used in computing basic net loss per share 58,209 56,297 57,757 55,720 Add potentially dilutive securities — — — — Weighted-average shares used in computing basic and diluted net loss per share 58,209 56,297 57,757 55,720
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table sets forth the weighted-average number of all potentially dilutive securities excluded from the computation in the table above because their effect would have been anti-dilutive (in thousands): Three Months Ended Nine Months Ended September 26, September 27, September 26, September 27, Options to purchase common stock 2,710 2,675 2,380 2,981 Restricted stock units 1,717 — 1,550 1 Employee stock purchase plan — 20 30 1 Total potentially dilutive securities 4,427 2,695 3,960 2,983

Derivative Financial Instrume39

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 26, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Foreign Exchange Contracts, Statement of Financial Position	The following table provides information about our foreign currency forward contracts outstanding as of September 26, 2015 (in thousands): Currency Contract Position Contract Amount (Local Currency) Contract Amount (U.S. Dollars) Japanese Yen Sell 2,716,297 $ 22,471 Taiwan Dollar Buy (40,006 ) (1,209 ) Korean Won Buy (687,168 ) (581 ) Total USD notional amount of outstanding foreign exchange contracts $ 20,681
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	The location and amount of losses and gains related to non-designated derivative instruments that matured in the three and nine months ended September 26, 2015 and September 27, 2014 in the Condensed Consolidated Statements of Operations are as follows (in thousands): Amount of Loss (Gain) Recognized on Derivatives Three Months Ended Nine Months Ended Derivatives Not Designated as Hedging Instruments Location of Loss (Gain) Recognized on Derivatives September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Foreign exchange forward contracts Other income (expense), net $ (902 ) $ 740 $ (217 ) $ 465

Basis of Presentation and Sum40

Basis of Presentation and Summary of Significant Accounting Policies (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 26, 2015	Dec. 27, 2014
Number of weeks in period	91 days	91 days	273 days	273 days		364 days
Forecast
Number of weeks in period					364 days

Concentration of Credit and O41

Concentration of Credit and Other Risks (Details) - Customer Concentration Risk - Customer	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 27, 2014
Revenues
Concentration Risk [Line Items]
Concentration risk percentage	56.80%	61.90%	62.20%	50.90%
Revenues | Micron
Concentration Risk [Line Items]
Concentration risk percentage		16.60%	12.60%	14.60%
Revenues | Intel
Concentration Risk [Line Items]
Concentration risk percentage	18.10%	18.90%	17.90%	18.30%
Revenues | Samsung
Concentration Risk [Line Items]
Concentration risk percentage	23.10%	10.80%	16.40%
Revenues | SK Hynix
Concentration Risk [Line Items]
Concentration risk percentage	15.60%	15.60%	15.30%	18.00%
Accounts Receivable
Concentration Risk [Line Items]
Number of customers			2		2
Accounts Receivable | Major Customer 1
Concentration Risk [Line Items]
Concentration risk percentage			28.00%		26.00%
Accounts Receivable | Major Customer 2
Concentration Risk [Line Items]
Concentration risk percentage			14.00%		18.00%

Goodwill and Intangible Asset42

Goodwill and Intangible Assets (Goodwill) (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 30,731	$ 30,731

Goodwill and Intangible Asset43

Goodwill and Intangible Assets (Intangible Assets) (Details)	9 Months Ended
	Sep. 26, 2015USD ($)	Dec. 27, 2014USD ($)
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Gross Amount, Beginning balance	$ 66,688,000
Additions/Disposals	2,400,000
Intangible Assets, Gross Amount, Ending balance	69,088,000
Accumulated Amortization, Beginning balance	34,899,000
Expense, net	9,820,000
Accumulated Amortization, Ending balance	44,719,000
Total	24,369,000	$ 31,789,000
Intangible Assets Net Excluding Goodwill [Roll Forward]
Intangible Assets, Gross Amount, Beginning balance	73,588,000
Additions/Disposals	0
Intangible Assets, Gross Amount, Ending balance	73,588,000
Intangible Assets, Net (Excluding Goodwill)	28,869,000	38,689,000
In-process research and development
Indefinite-lived Intangible Assets [Roll Forward]
In-process research and development, Beginning Balance	6,900,000
In-process research and development, Additions and Disposals	(2,400,000)
In-process research and development, Ending Balance	4,500,000
Intangible Assets Net Excluding Goodwill [Roll Forward]
In-process research and development project acquired and reclassified	2,400,000
Existing developed technologies (2)
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Gross Amount, Beginning balance	45,300,000
Additions/Disposals	2,400,000
Intangible Assets, Gross Amount, Ending balance	47,700,000
Accumulated Amortization, Beginning balance	29,097,000
Expense, net	7,830,000
Accumulated Amortization, Ending balance	36,927,000
Total	$ 10,773,000	16,203,000
Weighted Average Useful Life	2 years
Existing developed technologies (2) | MarTek
Finite-lived Intangible Assets [Roll Forward]
Intangible assets held for sale	$ 5,900
Trade name
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Gross Amount, Beginning balance	4,388,000
Additions/Disposals	0
Intangible Assets, Gross Amount, Ending balance	4,388,000
Accumulated Amortization, Beginning balance	970,000
Expense, net	328,000
Accumulated Amortization, Ending balance	1,298,000
Total	$ 3,090,000	3,418,000
Weighted Average Useful Life	7 years
Customer relationships
Finite-lived Intangible Assets [Roll Forward]
Intangible Assets, Gross Amount, Beginning balance	$ 17,000,000
Intangible Assets, Gross Amount, Ending balance	17,000,000
Accumulated Amortization, Beginning balance	4,832,000
Expense, net	1,662,000
Accumulated Amortization, Ending balance	6,494,000
Total	$ 10,506,000	$ 12,168,000
Weighted Average Useful Life	5 years

Goodwill and Intangible Asset44

Goodwill and Intangible Assets (Amortization) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 27, 2014
Property, Plant and Equipment [Line Items]
Amortization of intangible assets			$ 9,820
Finite-Lived Intangible Assets, Net, Amortization Expense, Rolling Maturity [Abstract]
2,015	$ 3,317		3,317
2,016	9,511		9,511
2,017	3,314		3,314
2,018	2,949		2,949
2,019	2,447		2,447
and thereafter	2,831		2,831
Total	24,369		24,369		$ 31,789
Cost of Sales | Intellectual Property
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	2,700	$ 4,400	7,800	$ 13,200
Selling, general and administrative | Intellectual Property
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	$ 700	$ 700	$ 2,000	$ 2,000

Restructuring Charges (Narrativ

Restructuring Charges (Narrative) (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 26, 2015USD ($)	Jun. 28, 2014USD ($)Employee	Mar. 29, 2014USD ($)positions	Sep. 26, 2015USD ($)	Sep. 27, 2014USD ($)Employee
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 2,000	$ 559	$ 2,084
Number of employees eliminated | Employee		2			52
Number of temporary positions eliminated | positions			9
Stock-based Compensation
Restructuring Cost and Reserve [Line Items]
Restructuring charges				500
Employee Severance and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 28	$ 59	$ 1,400	$ 59	$ 1,484
Property and Equipment Impairment
Restructuring Cost and Reserve [Line Items]
Restructuring charges					$ 600
Asset impairments			$ 600

Restructuring Charges (Activiti

Restructuring Charges (Activities) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 26, 2015	Jun. 28, 2014	Mar. 29, 2014	Sep. 26, 2015	Sep. 27, 2014
Restructuring Reserve [Roll Forward]
Accrual at beginning of period			$ 138	$ 584	$ 138
Restructuring charges			2,000	559	2,084
Cash payments				(618)	(1,592)
Adjustment to restructuring charges				3
Asset impairments					(600)
Non-cash settlements				(500)	(2)
Accrual at end of period	$ 28			28	28
Employee Severance and Benefits
Restructuring Reserve [Roll Forward]
Accrual at beginning of period			138	584	138
Restructuring charges	28	$ 59	1,400	59	1,484
Cash payments				(618)	(1,592)
Adjustment to restructuring charges				3
Asset impairments					0
Non-cash settlements					(2)
Accrual at end of period	28			28	28
Stock-based Compensation
Restructuring Reserve [Roll Forward]
Accrual at beginning of period				0
Restructuring charges				500
Cash payments				0
Adjustment to restructuring charges				0
Non-cash settlements				(500)
Accrual at end of period	$ 0			$ 0
Property and Equipment Impairment
Restructuring Reserve [Roll Forward]
Accrual at beginning of period			$ 0		0
Restructuring charges					600
Cash payments					0
Asset impairments					(600)
Non-cash settlements					0
Accrual at end of period					$ 0

Fair Value (Details)

Fair Value (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	$ 41,654	$ 49,897
Total	124,327	115,200
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	81,173	65,303
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	43,154	49,897
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	81,173	65,303
Money market funds | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	81,173	65,303
Money market funds | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Agency securities (Federal)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	1,500
Marketable securities	22,245	7,502
Agency securities (Federal) | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0
Marketable securities	0	0
Agency securities (Federal) | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	1,500
Marketable securities	22,245	7,502
U.S. Treasuries
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	19,409	42,395
U.S. Treasuries | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	0	0
U.S. Treasuries | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities	$ 19,409	$ 42,395

Marketable Securities (Details)

Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 41,641	$ 49,888
Gross Unrealized Gains	13	13
Gross Unrealized Losses	0	(4)
Fair Value	41,654	49,897
Amortized Cost
Due in one year or less	41,641
Due after one year to five years	0
Amortized Cost	41,641
Fair Value
Due in one year or less	41,654
Due after one year to five years	0
Fair Value	41,654
U.S. Treasuries
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,396	42,386
Gross Unrealized Gains	13	13
Gross Unrealized Losses	0	(4)
Fair Value	19,409	42,395
Agency securities (Federal)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	22,245	7,502
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 22,245	$ 7,502

Allowance for Doubtful Accoun49

Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 266	$ 265
Additions	0	5
Reductions	(11)	(4)
Balance at end of period	$ 255	$ 266

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Inventory Disclosure [Abstract]
Raw materials	$ 12,283	$ 10,646
Work-in-progress	13,029	12,813
Finished goods	1,688	2,089
Inventory, Net	$ 27,000	$ 25,548

Warranty (Details)

Warranty (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance at beginning of period	$ 1,592	$ 691
Accruals	1,855	1,932
Settlements	(2,284)	(1,594)
Balance at the end of period	$ 1,163	$ 1,029

Long-lived Assets (Narrative) (

Long-lived Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-lived assets to be disposed of	$ 0	$ 86	$ 8	$ 829
Gain on sale of assets		$ 200
Building
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-lived assets to be disposed of			600
Machinery and equipment
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-lived assets to be disposed of			$ 500

Long-lived Assets (Details)

Long-lived Assets (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Property, Plant and Equipment [Line Items]
Sub total	$ 251,272	$ 247,171
Less: accumulated depreciation and amortization	(230,433)	(224,135)
Net long-lived assets	20,839	23,036
Construction-in-progress	2,982	2,462
Total	23,821	25,498
Machinery and equipment
Property, Plant and Equipment [Line Items]
Sub total	149,948	145,995
Computer equipment and software
Property, Plant and Equipment [Line Items]
Sub total	28,838	28,953
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Sub total	5,396	5,402
Leasehold improvements
Property, Plant and Equipment [Line Items]
Sub total	$ 67,090	$ 66,821

Accumulated Other Comprehensi54

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized loss on marketable securities, net of tax of $428 at September 26, 2015 and December 27, 2014, respectively	$ (415)	$ (419)
Cumulative translation adjustments	(1,751)	(1,342)
Accumulated other comprehensive loss	(2,166)	(1,761)
Unrealized loss on marketable securities, tax benefit	$ 428	$ 428

Stockholders' Equity (Narrative

Stockholders' Equity (Narrative) (Details)	May. 28, 2015USD ($)executiveshares	Apr. 08, 2015shares	May. 05, 2014USD ($)executiveshares	May. 06, 2013executiveshares	Sep. 26, 2015USD ($)shares	Sep. 27, 2014USD ($)	Sep. 26, 2015USD ($)shares	Sep. 27, 2014USD ($)	Apr. 16, 2015USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense					$ 3,100,000	$ 3,934,000	$ 8,515,000	$ 10,023,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted | shares	195,000		350,000	355,000
Number of recipients | executive	7		7
Stock-based compensation expense	$ 1,500,000		$ 1,800,000
Awards vested | shares		443,750
Restricted Stock Units | Senior Executives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of recipients | executive				7
Restricted Stock Units | Non-executives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of recipients | executive				1
Stock options | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted | shares							450,000
Stock-based compensation expense							$ 1,700,000
Equity Incentive Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vested | shares							1,924,849
Total fair value of restricted stock units vested during the period						$ 200,000	$ 17,500,000	$ 7,300,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program authorized amount									$ 25,000,000
Stock repurchased during the period (in shares) | shares					472,800		873,162
Stock repurchased during the period, amount					$ 3,500,000		$ 7,000,000

Stockholders' Equity (Restricte

Stockholders' Equity (Restricted Stock Units) (Details) - Restricted Stock Units - $ / shares	Apr. 08, 2015	Sep. 26, 2015
Units
Awards vested	(443,750)
Equity Incentive Plan
Units
Beginning balance, restricted stock units		3,250,046
Awards granted		1,507,750
Awards vested		(1,924,849)
Awards canceled		(169,019)
Ending balance, restricted stock units		2,663,928
Weighted Average Grant Date Fair Value
Beginning Balance, Weighted Average Grant Date Fair Value		$ 6.07
Awards granted		8.66
Awards vested		6.04
Awards canceled		6.57
Ending Balance, Weighted Average Grant Date Fair Value		$ 7.52

Stockholders' Equity (Weighted

Stockholders' Equity (Weighted Average Assumptions) (Details) - Stock options	9 Months Ended
	Sep. 26, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
Expected volatility	47.50%
Risk-free interest rate	1.57%
Expected term (in years)	5 years 6 months 6 days

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Mar. 29, 2014	Sep. 26, 2015	Sep. 27, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restructuring charges			$ 2,000	$ 559	$ 2,084
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock, percent of market value				85.00%
Stock issued during the period	262,788	265,467		565,493	586,386
Stock-based Compensation
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restructuring charges				$ 500

Stock-Based Compensation (Inclu

Stock-Based Compensation (Included in Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 3,100	$ 3,934	$ 8,515	$ 10,023
Tax effect of stock-based compensation	0	0	0	0
Total stock-based compensation, net of tax	3,100	3,934	8,515	10,023
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	756	700	1,941	1,855
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	973	1,077	2,544	2,638
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 1,371	$ 2,157	$ 4,030	$ 5,530

Stock-Based Compensation (Weigh

Stock-Based Compensation (Weighted Average Assumptions) (Details) - Employee stock purchase plan	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility	52.20%	41.60%	52.10%	41.90%
Risk-free interest rate	0.14%	0.09%	0.10%	0.09%
Expected term (in years)	9 months 21 days	9 months 21 days	7 months 27 days	7 months 27 days

Stock-Based Compensation (Unrec

Stock-Based Compensation (Unrecognized Compensation Costs) (Details) $ in Thousands	9 Months Ended
	Sep. 26, 2015USD ($)
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Total unrecognized stock-based compensation expense	$ 16,229
Stock options
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Stock options	$ 1,457
Average Expected Recognition Period in years	3 years 4 months 8 days
Restricted stock units
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Restricted stock units and employee stock purchase plan	$ 14,309
Average Expected Recognition Period in years	2 years 1 month 4 days
Employee stock purchase plan
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized [Abstract]
Restricted stock units and employee stock purchase plan	$ 463
Average Expected Recognition Period in years	4 months 6 days

Net Loss per Share (Details)

Net Loss per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Numerator:
Net loss used in computing basic and diluted net loss per share	$ (2,525)	$ (277)	$ (904)	$ (17,314)
Denominator:
Weighted-average shares used in computing basic net loss per share	58,209	56,297	57,757	55,720
Add potentially dilutive securities	0	0	0	0
Weighted-average shares used in computing basic and diluted net loss per share	58,209	56,297	57,757	55,720

Net Loss per Share (Weighted-Av

Net Loss per Share (Weighted-Average Dilutive Securities) (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive securities	4,427	2,695	3,960	2,983
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive securities	2,710	2,675	2,380	2,981
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive securities	1,717	0	1,550	1
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive securities	0	20	30	1

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Income Tax Disclosure [Abstract]
Income tax provision	$ 215	$ 101	$ 359	$ 358

Commitments and Contingencies (

Commitments and Contingencies (Details) - MarTek $ in Millions	Jul. 17, 2015USD ($)	Jul. 13, 2015USD ($)tranche	Sep. 26, 2015USD ($)
Settled Litigation | Other income (expense), net
Loss Contingencies [Line Items]
Gain related to legal settlement			$ 1
Intellectual Property
Loss Contingencies [Line Items]
Litigation settlement amount		$ 2
Receivable from legal settlement, number of equal tranches | tranche		2
Cash | Intellectual Property
Loss Contingencies [Line Items]
Litigation settlement amount	$ 1.2
Notes Receivable | Intellectual Property
Loss Contingencies [Line Items]
Litigation settlement amount	$ 0.8

Derivative Financial Instrume66

Derivative Financial Instruments (Details) - Not Designated as Hedging Instrument - Foreign Exchange Forward ₩ in Thousands, ¥ in Thousands, TWD in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015USD ($)	Sep. 27, 2014USD ($)	Sep. 26, 2015USD ($)	Sep. 27, 2014USD ($)	Sep. 26, 2015KRW (₩)	Sep. 26, 2015TWD	Sep. 26, 2015JPY (¥)
Derivatives, Fair Value [Line Items]
Total USD notional amount of outstanding foreign exchange contracts	$ 20,681		$ 20,681
Other income (expense), net
Derivatives, Fair Value [Line Items]
Foreign exchange forward contracts	(902)	$ 740	(217)	$ 465
Sell | Japanese Yen
Derivatives, Fair Value [Line Items]
Derivative asset contract amount	22,471		22,471				¥ 2,716,297
Buy | Taiwan Dollar
Derivatives, Fair Value [Line Items]
Derivative liability contract amount	(1,209)		(1,209)			TWD (40,006)
Buy | Korean Won
Derivatives, Fair Value [Line Items]
Derivative liability contract amount	$ (581)		$ (581)		₩ (687,168)

Business Interruption Insuran67

Business Interruption Insurance Claim Recovery (Details) $ in Millions	3 Months Ended
	Sep. 26, 2015USD ($)
Other income (expense), net
Business Interruption Loss [Line Items]
Proceeds from payment from insurer arising from business interruption insurance claim	$ 1.5