FormFactor (FORM) 10-Q31 Oct 142014 Q3 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 27, 2014	Oct. 30, 2014
Document Information [Line Items]	'	'
Entity Registrant Name	'FORMFACTOR INC.	'
Entity Central Index Key	'0001039399	'
Current Fiscal Year End Date	'--12-27	'
Entity Filer Category	'Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	27-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	56,411,839

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		9 Months Ended
Share data in Thousands, except Per Share data, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Revenues	$73,933,000	$67,634,000	$197,245,000	$182,987,000
Cost of revenues	49,791,000	55,088,000	140,754,000	144,961,000
Gross profit	24,142,000	12,546,000	56,491,000	38,026,000
Operating expenses:	'	'	'	'
Research and development	11,198,000	10,301,000	32,019,000	32,145,000
Selling, general and administrative	13,309,000	12,952,000	38,754,000	41,057,000
Restructuring charges, net	28,000	143,000	2,084,000	4,215,000
Loss on sale of subsidiary	0	0	0	300,000
Impairment of long-lived assets	86,000	15,000	829,000	194,000
Total operating expenses	24,621,000	23,411,000	73,686,000	77,911,000
Operating loss	-479,000	-10,865,000	-17,195,000	-39,885,000
Interest income, net	75,000	95,000	233,000	298,000
Other income (expense), net	228,000	-91,000	6,000	541,000
Loss before income taxes	-176,000	-10,861,000	-16,956,000	-39,046,000
Provision (benefit) for income taxes	100,000	-100,000	400,000	-200,000
Net loss	($277,000)	($10,714,000)	($17,314,000)	($38,894,000)
Net loss per share:	'	'	'	'
Basic and Diluted (In dollars per share)	$0	($0.20)	($0.31)	($0.72)
Weighted-average number of shares used in per share calculations:	'	'	'	'
Basic and Diluted (In shares)	56,297	54,437	55,720	54,070

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Net loss	($277)	($10,714)	($17,314)	($38,894)
Other comprehensive (loss) income, net of tax:	'	'	'	'
Foreign currency translation adjustments	-814	267	-376	-1,298
Unrealized gains (losses) on available-for-sale marketable securities	1	10	25	-112
Other comprehensive (loss) income, net of tax	-813	277	-351	-1,410
Comprehensive loss	($1,090)	($10,437)	($17,665)	($40,304)

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (Unaudited) (USD $)	Sep. 27, 2014	Dec. 28, 2013
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Current assets:	'	'
Cash and cash equivalents	$89,264	$59,196
Marketable securities	65,103	91,895
Accounts receivable, net	47,776	30,189
Inventories, net	25,902	20,707
Deferred tax assets	2,837	2,776
Refundable income taxes	782	782
Prepaid expenses and other current assets	7,730	6,106
Total current assets	239,394	211,651
Restricted cash	435	435
Property, plant and equipment, net	26,610	35,190
Goodwill	30,731	30,731
Intangibles, net	42,255	57,470
Deferred tax assets	3,881	3,960
Other assets	1,225	1,271
Total assets	344,531	340,708
Current liabilities:	'	'
Accounts payable	21,267	16,313
Accrued liabilities	19,102	13,985
Capital leases, current portion	0	270
Income taxes payable	625	172
Deferred revenue	5,466	7,030
Total current liabilities	46,460	37,770
Long-term income taxes payable	2,208	2,497
Deferred tax liabilities	3,029	3,029
Deferred rent and other liabilities	3,603	3,326
Total liabilities	55,300	46,622
Commitments and contingencies (Note 17)	'	'
Stockholdersâ€™ equity:	'	'
Preferred stock, $0.001 par value: 10,000,000 shares authorized; no shares issued and outstanding at September 27, 2014 and December 28, 2013, respectively	0	0
Common stock, $0.001 par value: 250,000,000 shares authorized; 56,411,839 and 54,649,600 shares issued and outstanding at September 27, 2014 and December 28, 2013, respectively	56	55
Additional paid-in capital	708,440	695,631
Accumulated other comprehensive loss	-600	-249
Accumulated deficit	-418,665	-401,351
Total stockholdersâ€™ equity	289,231	294,086
Total liabilities and stockholdersâ€™ equity	$344,531	$340,708

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Sep. 27, 2014	Dec. 28, 2013
Stockholders' Equity:	'	'
Preferred stock, par value, in dollars per share	$0.00	$0.00
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	$0.00	$0.00
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	56,411,839	54,649,600
Common stock, shares outstanding	56,411,839	54,649,600

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013
Cash flows from operating activities:	'	'
Net loss	($17,314)	($38,894)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation and amortization	24,155	21,854
Amortization of discount on investments	199	307
Stock-based compensation expense	10,023	9,125
Deferred income tax (benefit) provision	-44	146
Provision (recovery) for doubtful accounts receivable	1	-19
Provision for excess and obsolete inventories	5,530	7,829
Loss on disposal and write-off of long-lived assets	41	354
Impairment of long-lived assets	829	194
Loss on sale of subsidiary	0	300
Non-cash restructuring	600	2,743
Foreign currency transaction losses	880	224
Changes in assets and liabilities:	'	'
Accounts receivable	-17,918	-17,994
Inventories	-10,725	-6,747
Prepaid expenses and other current assets	-1,087	1,857
Refundable income taxes	0	5,133
Other assets	16	437
Accounts payable	5,998	10,740
Accrued liabilities	5,484	-1,122
Income tax payable	160	6
Deferred rent and other liabilities	151	53
Deferred revenues	-1,564	920
Net cash provided by (used in) operating activities	5,415	-2,554
Cash flows from investing activities:	'	'
Acquisition of property, plant and equipment	-4,539	-7,363
Proceeds from sale of property, plant and equipment	820	0
Proceeds (use of cash) from sale of subsidiary	85	-238
Purchases of marketable securities	-31,693	-69,211
Proceeds from maturities of marketable securities	58,323	63,470
Change in restricted cash	0	-118
Proceeds from sale of marketable securities	0	2,000
Net cash provided by (used in) investing activities	22,996	-11,460
Cash flows from financing activities:	'	'
Proceeds from issuances of common stock	2,813	2,607
Purchase and retirement of common stock	0	-5
Payments made on capital leases	-271	-473
Net cash provided by financing activities	2,542	2,129
Effect of exchange rate changes on cash and cash equivalents	-885	-888
Net increase (decrease) in cash and cash equivalents	30,068	-12,773
Cash and cash equivalents, beginning of period	59,196	72,243
Cash and cash equivalents, end of period	89,264	59,470
Supplemental cash flow disclosures:	'	'
Changes in accounts payable and accrued liabilities related to property, plant and equipment purchases	-1,105	-2,293
Income and property taxes paid (refunded), net	$789	($6,238)

Basis_of_Presentation_and_Summ

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 27, 2014
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 27, 2014 are not necessarily indicative of the results that may be expected for the year ending December 27, 2014, or for any other period. The balance sheet at December 28, 2013 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 28, 2013 included in our Annual Report on Form 10-K filed with the SEC on March 7, 2014.

	Fiscal year. We operate on a 52/53 week fiscal year, whereby the fiscal year ends on the last Saturday of December. Fiscal 2014 and 2013 each contain 52 weeks and the three and nine months ended September 27, 2014 and September 28, 2013 each contained 13 and 39 weeks, respectively. Fiscal 2014 will end on December 27, 2014.

	Critical Accounting Policies. Our critical accounting policies have not changed during the three and nine months ended September 27, 2014 from those disclosed in our Annual Report on Form 10-K for the year ended December 28, 2013.

	Reclassifications. Certain reclassifications have been made to the prior year's Condensed Consolidated Balance Sheet to conform to the current period presentation.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	9 Months Ended
Recent Accounting Pronouncements	Sep. 27, 2014
Accounting Policies [Abstract]	'
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements

	In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, "Revenue from Contracts with Customers". The guidance requires an entity to recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which an entity expects to be entitled in exchange for those goods or services. The guidance also requires expanded disclosures relating to the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Additionally, qualitative and quantitative disclosures are required about customer contracts, significant judgments and changes in judgments, and assets recognized from the costs to obtain or fulfill a contract. The standard permits the use of either the retrospective or cumulative effect transition methods. This guidance will replace most existing revenue recognition guidance in United States generally accepted accounting principles when it becomes effective, which for us will be at the beginning of the first quarter of fiscal year 2017 using one of the two prescribed transition methods. Early adoption is not permitted. We are evaluating the impact of the revenue recognition guidance on our consolidated financial statements and related disclosures. We have not yet selected a transition method nor have we determined the effect of the standard on our ongoing financial reporting.

	In August 2014, the FASB issued ASU No. 2014-15, "Presentation of Financial Statements-Going Concern (Subtopic 205-40)". This ASU provides guidance to determine when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date that the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The standard will be effective for us in fiscal year 2017. We are evaluating the impact of the adoption of this accounting standard update on our consolidated financial statements and related disclosures.

Concentration_of_Credit_and_Ot

Concentration of Credit and Other Risks	9 Months Ended
	Sep. 27, 2014
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
		27-Sep-14		28-Sep-13		September 27, 2014		September 28, 2013
	Intel	18.9	%	15.5	%	18.3	%	15.8	%
	Micron	16.6		19		14.6		10.2

	SK hynix	15.6		12.4		18		17

	Samsung	10.8		*		*		*

		61.9	%	46.9	%	50.9	%	43	%
	* Less than 10% of revenues.
	At September 27, 2014, two customers accounted for 25% and 22% of gross accounts receivable. At December 28, 2013, three customers accounted for approximately 21%, 15% and 11% 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-cyclical market patterns 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
Goodwill and Intangible Assets	Sep. 27, 2014
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 27, 2014 and remained unchanged from the amounts recorded as of December 28, 2013. The Company has not recorded any historical goodwill impairments as of September 27, 2014.

	The changes in intangible assets during the nine months ended September 27, 2014 and the net book value of intangible assets as of September 27, 2014 and December 28, 2013 were as follows (in thousands):


		Intangible Assets, Gross Amount						Accumulated Amortization						Intangible Assets, Net				Weighted Average Useful Life
	Other Intangible Assets (1)	28-Dec-13		Additions/Disposals		September 27, 2014		28-Dec-13		Expense, net		September 27, 2014		December 28, 2013		September 27, 2014		September 27, 2014
	Existing developed technologies	$	51,248	$	—	$	51,248	$	18,955	$	13,197	$	32,152	$	32,293	$	19,096	2
	Existing developed technologies	$	51,248	$	—	$	51,248	$	18,955	$	13,197	$	32,152	$	32,293	$	19,096	2
	Trade name	4,388		—		4,388		530		330		860		3,858		3,528		8
	Trade name	4,388		—		4,388		530		330		860		3,858		3,528		8
	Customer relationships	17,000		—		17,000		2,581		1,688		4,269		14,419		12,731		6
	Customer relationships	17,000		—		17,000		2,581		1,688		4,269		14,419		12,731		6
	Total finite-lived intangible assets	72,636		—		72,636		22,066		15,215		37,281		50,570		35,355
	Total finite-lived intangible assets	72,636		—		72,636		22,066		15,215		37,281		50,570		35,355
	In-process research and development	6,900		—		6,900		—		—		—		6,900		6,900
	In-process research and development	6,900		—		6,900		—		—		—		6,900		6,900
	Total intangible assets	$	79,536	$	—	$	79,536	$	22,066	$	15,215	$	37,281	$	57,470	$	42,255
	Total intangible assets	$	79,536	$	—	$	79,536	$	22,066	$	15,215	$	37,281	$	57,470	$	42,255
	(1) Excludes fully amortized intangible assets

	The in-process research and development ("IPR&D") assets are classified as indefinite lived intangible assets that are not currently subject to amortization but are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. The IPR&D assets will be subject to amortization upon completion of their respective research projects and at the start of commercialization. The fair values assigned to IPR&D assets were 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 an 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 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. For the three and nine months ended September 28, 2013, amortization expense of $3.4 million and $0.7 million, and $10.4 million and $2.2 million, respectively, was included in cost of revenues and selling, general and administrative expenses.
	Based on the carrying values of the finite-lived intangible assets recorded as of September 27, 2014 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
	2014	$	3,566
	2014	$	3,566
	2015	12,739
	2015	12,739
	2016	8,720
	2016	8,720
	2017	2,551
	2017	2,551
	2018	2,501
	2018	2,501
	and thereafter	5,278
	and thereafter	5,278
	Total	$	35,355
	Total	$	35,355

Restructuring_Charges

Restructuring Charges	9 Months Ended
	Sep. 27, 2014
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 nine months ended September 27, 2014 and September 28, 2013, the purposes of which were to improve operating efficiency, streamline and simplify our operations and reduce our operating costs, are discussed below.

	2014 Restructuring Activities

	On January 27, 2014, we announced a global organizational restructuring and cost reduction plan (the "Q1 2014 Restructuring Plan"). As part of the plan, the Company 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 liabilities we accrued represent our best estimate of the obligations we expect to incur and could be subject to adjustment as market conditions change. The activities comprising these restructuring activities and the related cash payments were substantially completed and paid by September 27, 2014.

	2013 Restructuring Activities

	In the first quarter of fiscal 2013, we implemented a restructuring plan (the "Q1 2013 Restructuring Plan") which resulted in the reduction of our global workforce by 31 employees across the organization. In addition we reduced our temporary workforce by approximately 20 positions. We also suspended development activities and engineering efforts for our next generation DRAM Matrix platform and terminated development activities for a certain SoC product platform. We recorded $4.0 million of restructuring charges during the first quarter of fiscal 2013, which was comprised of $1.3 million in severance and related benefits and $2.7 million in impairment charges for certain equipment that would no longer be utilized. In the second quarter of fiscal 2013, we recorded $0.1 million of severance and related benefits due to the reduction of 4 employees across the organization. The activities comprising these restructuring activities were completed in fiscal 2013.

	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


	The activities in the restructuring accrual for the nine months ended September 28, 2013 were as follows (in thousands)



		Employee Severance and Benefits			Property and Equipment Impairment			Contract Termination and Other Costs			Total
	Accrual at December 29, 2012	$	548		$	—		$	68		$	616

	Restructuring charges	1,613			2,743			14			4,370

	Cash payments	(1,851		)	(32		)	(17		)	(1,900		)
	Asset impairment	—			(2,743		)	—			(2,743		)

	Adjustment to restructuring charges	(152		)	(5		)	—			(157		)

	Other settlements	9			37			(65		)	(19		)

	Accrual at September 28, 2013	$	167		$	—		$	—		$	167

Fair_Value

Fair Value	9 Months Ended
	Sep. 27, 2014
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, commercial paper and foreign currency derivatives (see Note 18 to the Condensed Consolidated Financial Statements - Derivative Financial Instruments, for a discussion of fair value of foreign currency derivatives).

	Fair value measured on a recurring basis as of September 27, 2014 was as follows (in thousands):


		Level 1		Level 2		Total
	Assets:
	Cash equivalents
	Money market funds	$	50,087	$	—	$	50,087

	Marketable securities
	U.S. Treasuries	—		47,437		47,437

	Agency securities (Federal)	—		17,666		17,666

	Total	$	50,087	$	65,103	$	115,190


	Fair value measured on a recurring basis as of December 28, 2013 was as follows (in thousands):




		Level 1		Level 2		Total
	Assets:
	Cash equivalents
	Money market funds	$	27,943	$	—	$	27,943

	Commercial paper	—		11,623		11,623

	Marketable securities
	U.S. Treasuries	—		49,014		49,014

	Agency securities (Federal)	—		31,258		31,258

	Total	$	27,943	$	91,895	$	119,838


	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 27, 2014 and September 28, 2013.
	Assets Measured at Fair Value on a Non-Recurring Basis

	There were no assets measured at fair value on a nonrecurring basis during the three and nine months ended September 27, 2014.

Marketable_Securities

Marketable Securities	9 Months Ended
	Sep. 27, 2014
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 27, 2014 consisted of the following (in thousands):



		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	U.S. Treasuries	$	47,381	$	55	$	—		$	47,436

	Agency securities (Federal)	17,666		1		—			17,667

		$	65,047	$	56	$	—		$	65,103



	Marketable securities at December 28, 2013 consisted of the following (in thousands):



		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	U.S. Treasuries	$	48,991	$	33	$	(10	)	$	49,014

	Commercial paper	11,623		—		—			11,623

	Agency securities (Federal)	31,261		1		(4		)	31,258

		$	91,875	$	34	$	(14	)	$	91,895


	The marketable securities with gross unrealized losses have been in a loss position for less than twelve months as of September 27, 2014 and December 28, 2013, 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, review of current market liquidity, interest rate risk, the financial condition of the issuer, as well as 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 27, 2014 were as follows (in thousands):




		Amortized Cost		Fair Value
	Due in one year or less	$	45,664	$	45,696

	Due after one year to five years	19,383		19,407

		$	65,047	$	65,103


	Realized gains and losses on sales and maturities of marketable securities were immaterial for the three and nine months ended September 27, 2014 and September 28, 2013, respectively.

Allowance_for_Doubtful_Account

Allowance for Doubtful Accounts	9 Months Ended
	Sep. 27, 2014
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 27, 2014 and September 28, 2013, respectively, is as follows (in thousands):




		September 27,			September 28,
		2014			2013
	Balance at beginning of period	$	265		$	290

	Additions	5			—

	Reductions	(4		)	(19		)
	Balance at end of period	$	266		$	271

Inventories

Inventories	9 Months Ended
	Sep. 27, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories

	Inventories consisted of the following (in thousands):


		September 27,		December 28,
		2014		2013
	Raw materials	$	9,988	$	7,411

	Work-in-progress	14,342		10,531

	Finished goods	1,572		2,765

		$	25,902	$	20,707

Warranty

Warranty	9 Months Ended
	Sep. 27, 2014
Product Warranties Disclosures [Abstract]	'
Warranty	'
	Warranty

	A reconciliation of the changes in our warranty liability for the nine months ended September 27, 2014 and September 28, 2013, respectively, is as follows (in thousands):


		September 27,			September 28,
		2014			2013
	Balance at beginning of period	$	691		$	734

	Accruals	1,932			1,230

	Settlements	(1,594		)	(930		)
	Balance at the end of period	$	1,029		$	1,034

Longlived_Assets

Long-lived Assets	9 Months Ended
	Sep. 27, 2014
Long-Lived Assets Disclosure [Abstract]	'
Long-lived Assets	'
	Long-lived Assets

	Impairment of long-lived assets

	During the three and nine months ended September 27, 2014, we recorded $86 thousand and $0.8 million of impairments related to manufacturing assets we no longer utilize. During the three and nine months ended September 28, 2013, we recorded $15 thousand and $0.2 million, respectively, of impairments related to manufacturing assets we no longer utilize. These charges are included in "Impairment of long-lived assets" in the Condensed Consolidated Statements of Operations in their respective periods.

	During the three months ended September 27, 2014, we ceased to use fully depreciated assets with an acquired cost of $0.3 million.

	Long-lived Assets

	Property, plant and equipment consisted of the following (in thousands):



		September 27,			December 28,
		2014			2013
	Building	$	—		$	790

	Machinery and equipment	146,757			143,463

	Computer equipment and software	34,352			34,547

	Capital leases	—			866

	Furniture and fixtures	5,444			5,495

	Leasehold improvements	66,921			67,384

	Sub total	253,474			252,545

	Less: accumulated depreciation and amortization	(228,062		)	(221,346		)
	Net long-lived assets	25,412			31,199

	Construction-in-progress	1,198			3,991

	Total	$	26,610		$	35,190





	Assets held for sale

	During the nine months ended September 27, 2014, we reclassified $0.8 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 building was sold during the third quarter of fiscal 2014 and we recorded a gain of $0.2 million on the sale.

	Refer to Note 4 to the Condensed Consolidated Financial Statements - Goodwill and Intangible Assets for further details relating to our intangible long-lived assets.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 27, 2014
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. Components of accumulated other comprehensive loss were as follows (in thousands):



		September 27,			December 28,
		2014			2013
	Unrealized loss on marketable securities, net of tax of $439 at September 27, 2014 and $428 at December 28, 2013, respectively	$	(384	)	$	(409	)
	Cumulative translation adjustments	(216		)	160

	Accumulated other comprehensive loss	$	(600	)	$	(249	)

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Sep. 27, 2014
Stockholders' Equity Note [Abstract]	'
Stockholders' Equity	'
	Stockholders’ Equity

	Restricted Stock Units

	Restricted stock unit activity under our equity incentive plans during the nine months ended September 27, 2014 is set forth below:



		Units		Weighted Average Grant Date Fair Value
	Restricted stock units at December 28, 2013	2,929,639		$	5.88

	Awards granted	1,900,000		6.52

	Awards vested	(1,175,853	)	6.42

	Awards canceled	(255,801	)	6.06

	Restricted stock units at September 27, 2014	3,397,985		$	6.04


	On May 5, 2014, we issued 350,000 shares of restricted stock units to seven senior executives of our company that will vest based on certain market performance criteria. The performance criteria are based on the Company's Total Shareholder Return (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 compensation cost will be recognized ratably over the requisite service period. During the nine months ended September 27, 2014, we recorded $0.4 million of stock-based compensation expense related to these awards.

	The total fair value of restricted stock units vested during the three and nine months ended September 27, 2014 and September 28, 2013 was $0.2 million and $7.3 million, and $0.1 million and $3.4 million, respectively.

	Stock Options

	During the three and nine months ended September 27, 2014 and September 28, 2013, we did not grant any stock options.

StockBased_Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 27, 2014
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 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 27,			September 28,				September 27,			September 28,
		2014			2013				2014			2013
	Stock-based compensation included in:

	Cost of revenues	$	700		$	547			$	1,855		$	1,709

	Research and development	1,077			810				2,638			2,652

	Selling, general and administrative	2,157			1,601				5,530			4,764

	Total stock-based compensation	3,934			2,958				10,023			9,125

	Tax effect of stock-based compensation	—			—				—			—

	Total stock-based compensation, net of tax	$	3,934		$	2,958			$	10,023		$	9,125


	Employee Stock Purchase Plan

	Under the 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 27, 2014 and September 28, 2013, we issued 265,467 and 296,245 ESPP shares, respectively. During the nine months ended September 27, 2014 and September 28, 2013, we issued 586,386 and 583,173 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 27,		September 28,			September 27,			September 28,
		2014		2013			2014			2013
	ESPP:

	Dividend yield	—	%	—	%		—	%		—	%
	Expected volatility	41.6	%	39.7	%		41.9	%		39.6	%
	Risk-free interest rate	0.09	%	0.13	%		0.09	%		0.12	%
	Expected term (in years)	0.81		0.81			0.66			0.66



	Unrecognized Compensation Costs

	At September 27, 2014, the unrecognized stock-based compensation, adjusted for estimated forfeitures, was as follows (in thousands):


		Unrecognized Expense			Average Expected Recognition Period in years
	Stock options	$	219		0.57

	Restricted stock units	12,152			1.4

	Employee stock purchase plan	350			0.35

	Total unrecognized stock-based compensation expense	$	12,721

Net_Loss_per_Share

Net Loss per Share	9 Months Ended
	Sep. 27, 2014
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 27, 2014 and September 28, 2013, respectively, was based only on the weighted-average number of shares outstanding during that 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 27,				September 28,			September 27,			September 28,
		2014				2013			2014			2013
	Numerator:

	Net loss used in computing basic and diluted net loss per share	$	(277	)		$	(10,714	)	$	(17,314	)	$	(38,894	)
	Denominator:
	Weighted-average shares used in computing basic net loss per share	56,297				54,437			55,720			54,070

	Add potentially dilutive securities	—				—			—			—

	Weighted-average shares used in computing basic and diluted net loss per share	56,297				54,437			55,720			54,070


	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 27,			September 28,			September 27,		September 28,
		2014			2013			2014		2013
	Options to purchase common stock	2,675			3,577			2,981		3,917

	Restricted stock units	—			278			1		512

	Employee stock purchase plan	20			46			1		1

	Total potentially dilutive securities	2,695			3,901			2,983		4,430

Income_Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 27, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes

	We recorded an income tax provision of $0.1 million and $0.4 million for the three and nine months ended September 27, 2014, respectively, and an income tax benefit of $0.1 million and $0.2 million, respectively, for the three and nine months ended September 28, 2013. Income tax provisions reflect the tax provision on our operations in the U.S. and foreign jurisdictions and the tax benefit from the lapsing of the 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
Commitments and Contingencies	Sep. 27, 2014
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. During the three months ended September 27, 2014, we extended an operating lease term relating to our San Jose, California facility from April 2016 to November 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 27, 2014 from those disclosed in our Annual Report on Form 10-K as of December 28, 2013.

	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 27, 2014, or in our fiscal 2013. We do not believe that any loss from environmental remediation liabilities would be in an amount material to our financial statements.
	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 wafer probe cards 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 27, 2014.
	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 27, 2014, 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 27, 2014, 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 commercial litigation relating to intellectual property, as well as third party initiated patent office proceedings in the United States and foreign patent offices.

	No provision has been made for intellectual property litigation because we believe that it is not probable that a liability had been incurred as of September 27, 2014. We could incur material attorneys' fees in prosecuting and defending actions related to intellectual property.

	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. In February 2014, the Court granted the Company’s motion to strike portions of Plaintiff’s first amended complaint, clarifying the scope of the putative class. A second amended complaint has also been filed. Procedurally, the case is in the early stages of litigation and no defined class has been certified. The parties participated in a mediation during the third quarter of fiscal 2014, which did not result in a settlement. The Company currently believes that any settlement reached would be in an amount that is not material to the Company's financial statements. The Company denies the allegations contained in the lawsuit and, based on available information, believes it has significant defenses to the allegations of the lawsuit. If the matter is not settled, the Company could incur material attorneys’ fees in defending the lawsuit.

Derivative_Financial_Instrumen

Derivative Financial Instruments	9 Months Ended
	Sep. 27, 2014
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 27, 2014 (in thousands):


	Currency	Contract Position	Contract Amount (Local Currency)		Contract Amount (U.S. Dollars)
	Japanese Yen	Sell	1,440,176		$	13,154

	Taiwan Dollar	Buy	(30,418	)	(1,005		)
	Korean Won	Buy	(1,819,141	)	(1,741		)
	Total USD notional amount of outstanding foreign exchange contracts				$	10,408


	The contracts were entered into on September 26, 2014 and matured on October 24, 2014. 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 27, 2014. Additionally, no gains or losses relating to the outstanding derivative contracts were recorded in the three and nine months ended September 27, 2014.

	The location and amount of gains and losses related to non-designated derivative instruments that matured in the three and nine months ended September 27, 2014 and September 28, 2013 in the Condensed Consolidated Statements of Operations are as follows (in thousands):



			Amount of Gain (Loss) Recognized on Derivatives
			Three Months Ended						Nine Months Ended
	Derivatives Not Designated as Hedging Instruments	Location of Gain (Loss) Recognized on Derivatives	September 27, 2014			September 28, 2013				September 27, 2014		September 28, 2013
	Foreign exchange forward contracts	Other income (expense), net	$	740		$	(19	)		$	465	$	(270	)

Basis_of_Presentation_and_Summ1

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 27, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Fiscal Period, Policy	'
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 2014 and 2013 each contain 52 weeks and the three and nine months ended September 27, 2014 and September 28, 2013 each contained 13 and 39 weeks, respectively. Fiscal 2014 will end on December 27, 2014.
Fair Value Measurement, Policy	'
	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, commercial paper and foreign currency derivatives (see Note 18 to the Condensed Consolidated Financial Statements - Derivative Financial Instruments, for a discussion of fair value of foreign currency derivatives)

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	9 Months Ended
Goodwill and Intangible Assets (Tables)	Sep. 27, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of Finite-Lived Intangible Assets	'
	The changes in intangible assets during the nine months ended September 27, 2014 and the net book value of intangible assets as of September 27, 2014 and December 28, 2013 were as follows (in thousands):


		Intangible Assets, Gross Amount						Accumulated Amortization						Intangible Assets, Net				Weighted Average Useful Life
	Other Intangible Assets (1)	28-Dec-13		Additions/Disposals		September 27, 2014		28-Dec-13		Expense, net		September 27, 2014		December 28, 2013		September 27, 2014		September 27, 2014
	Existing developed technologies	$	51,248	$	—	$	51,248	$	18,955	$	13,197	$	32,152	$	32,293	$	19,096	2
	Existing developed technologies	$	51,248	$	—	$	51,248	$	18,955	$	13,197	$	32,152	$	32,293	$	19,096	2
	Trade name	4,388		—		4,388		530		330		860		3,858		3,528		8
	Trade name	4,388		—		4,388		530		330		860		3,858		3,528		8
	Customer relationships	17,000		—		17,000		2,581		1,688		4,269		14,419		12,731		6
	Customer relationships	17,000		—		17,000		2,581		1,688		4,269		14,419		12,731		6
	Total finite-lived intangible assets	72,636		—		72,636		22,066		15,215		37,281		50,570		35,355
	Total finite-lived intangible assets	72,636		—		72,636		22,066		15,215		37,281		50,570		35,355
	In-process research and development	6,900		—		6,900		—		—		—		6,900		6,900
	In-process research and development	6,900		—		6,900		—		—		—		6,900		6,900
	Total intangible assets	$	79,536	$	—	$	79,536	$	22,066	$	15,215	$	37,281	$	57,470	$	42,255
	Total intangible assets	$	79,536	$	—	$	79,536	$	22,066	$	15,215	$	37,281	$	57,470	$	42,255
	(1) Excludes fully amortized intangible assets
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	'
	Based on the carrying values of the finite-lived intangible assets recorded as of September 27, 2014 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
	2014	$	3,566
	2014	$	3,566
	2015	12,739
	2015	12,739
	2016	8,720
	2016	8,720
	2017	2,551
	2017	2,551
	2018	2,501
	2018	2,501
	and thereafter	5,278
	and thereafter	5,278
	Total	$	35,355
	Total	$	35,355

Restructuring_Charges_Tables

Restructuring Charges (Tables)	9 Months Ended
	Sep. 27, 2014
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 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


	The activities in the restructuring accrual for the nine months ended September 28, 2013 were as follows (in thousands)



		Employee Severance and Benefits			Property and Equipment Impairment			Contract Termination and Other Costs			Total
	Accrual at December 29, 2012	$	548		$	—		$	68		$	616

	Restructuring charges	1,613			2,743			14			4,370

	Cash payments	(1,851		)	(32		)	(17		)	(1,900		)
	Asset impairment	—			(2,743		)	—			(2,743		)

	Adjustment to restructuring charges	(152		)	(5		)	—			(157		)

	Other settlements	9			37			(65		)	(19		)

	Accrual at September 28, 2013	$	167		$	—		$	—		$	167

Fair_Value_Tables

Fair Value (Tables)	9 Months Ended
	Sep. 27, 2014
Fair Value Disclosures [Abstract]	'
Fair Value, Assets Measured on Recurring Basis	'
	Fair value measured on a recurring basis as of September 27, 2014 was as follows (in thousands):


		Level 1		Level 2		Total
	Assets:
	Cash equivalents
	Money market funds	$	50,087	$	—	$	50,087

	Marketable securities
	U.S. Treasuries	—		47,437		47,437

	Agency securities (Federal)	—		17,666		17,666

	Total	$	50,087	$	65,103	$	115,190


	Fair value measured on a recurring basis as of December 28, 2013 was as follows (in thousands):




		Level 1		Level 2		Total
	Assets:
	Cash equivalents
	Money market funds	$	27,943	$	—	$	27,943

	Commercial paper	—		11,623		11,623

	Marketable securities
	U.S. Treasuries	—		49,014		49,014

	Agency securities (Federal)	—		31,258		31,258

	Total	$	27,943	$	91,895	$	119,838

Marketable_Securities_Tables

Marketable Securities (Tables)	9 Months Ended
	Sep. 27, 2014
Investments, Debt and Equity Securities [Abstract]	'
Schedule of Available-for-sale Securities Reconciliation	'
	Marketable securities at September 27, 2014 consisted of the following (in thousands):



		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	U.S. Treasuries	$	47,381	$	55	$	—		$	47,436

	Agency securities (Federal)	17,666		1		—			17,667

		$	65,047	$	56	$	—		$	65,103



	Marketable securities at December 28, 2013 consisted of the following (in thousands):



		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	U.S. Treasuries	$	48,991	$	33	$	(10	)	$	49,014

	Commercial paper	11,623		—		—			11,623

	Agency securities (Federal)	31,261		1		(4		)	31,258

		$	91,875	$	34	$	(14	)	$	91,895

Investments Classified by Contractual Maturity Date	'
	Contractual maturities of marketable securities as of September 27, 2014 were as follows (in thousands):




		Amortized Cost		Fair Value
	Due in one year or less	$	45,664	$	45,696

	Due after one year to five years	19,383		19,407

		$	65,047	$	65,103

Allowance_for_Doubtful_Account1

Allowance for Doubtful Accounts (Tables)	9 Months Ended
	Sep. 27, 2014
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 27, 2014 and September 28, 2013, respectively, is as follows (in thousands):




		September 27,			September 28,
		2014			2013
	Balance at beginning of period	$	265		$	290

	Additions	5			—

	Reductions	(4		)	(19		)
	Balance at end of period	$	266		$	271

Inventory_Tables

Inventory (Tables)	9 Months Ended
	Sep. 27, 2014
Inventory Disclosure [Abstract]	'
Schedule of Inventory, Current	'
	Inventories consisted of the following (in thousands):


		September 27,		December 28,
		2014		2013
	Raw materials	$	9,988	$	7,411

	Work-in-progress	14,342		10,531

	Finished goods	1,572		2,765

		$	25,902	$	20,707

Warranty_Tables

Warranty (Tables)	9 Months Ended
	Sep. 27, 2014
Product Warranties Disclosures [Abstract]	'
Schedule of Product Warranty Liability	'
	A reconciliation of the changes in our warranty liability for the nine months ended September 27, 2014 and September 28, 2013, respectively, is as follows (in thousands):


		September 27,			September 28,
		2014			2013
	Balance at beginning of period	$	691		$	734

	Accruals	1,932			1,230

	Settlements	(1,594		)	(930		)
	Balance at the end of period	$	1,029		$	1,034

Longlived_Assets_Tables

Long-lived Assets (Tables)	9 Months Ended
	Sep. 27, 2014
Long-Lived Assets Disclosure [Abstract]	'
Property, plant and equipment Including Construction-in-progress	'
	Property, plant and equipment consisted of the following (in thousands):



		September 27,			December 28,
		2014			2013
	Building	$	—		$	790

	Machinery and equipment	146,757			143,463

	Computer equipment and software	34,352			34,547

	Capital leases	—			866

	Furniture and fixtures	5,444			5,495

	Leasehold improvements	66,921			67,384

	Sub total	253,474			252,545

	Less: accumulated depreciation and amortization	(228,062		)	(221,346		)
	Net long-lived assets	25,412			31,199

	Construction-in-progress	1,198			3,991

	Total	$	26,610		$	35,190

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 27, 2014
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. Components of accumulated other comprehensive loss were as follows (in thousands):



		September 27,			December 28,
		2014			2013
	Unrealized loss on marketable securities, net of tax of $439 at September 27, 2014 and $428 at December 28, 2013, respectively	$	(384	)	$	(409	)
	Cumulative translation adjustments	(216		)	160

	Accumulated other comprehensive loss	$	(600	)	$	(249	)

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 27, 2014
Stockholders' Equity Note [Abstract]	'
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	'
	Restricted stock unit activity under our equity incentive plans during the nine months ended September 27, 2014 is set forth below:



		Units		Weighted Average Grant Date Fair Value
	Restricted stock units at December 28, 2013	2,929,639		$	5.88

	Awards granted	1,900,000		6.52

	Awards vested	(1,175,853	)	6.42

	Awards canceled	(255,801	)	6.06

	Restricted stock units at September 27, 2014	3,397,985		$	6.04

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 27, 2014
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 27,			September 28,				September 27,			September 28,
		2014			2013				2014			2013
	Stock-based compensation included in:

	Cost of revenues	$	700		$	547			$	1,855		$	1,709

	Research and development	1,077			810				2,638			2,652

	Selling, general and administrative	2,157			1,601				5,530			4,764

	Total stock-based compensation	3,934			2,958				10,023			9,125

	Tax effect of stock-based compensation	—			—				—			—

	Total stock-based compensation, net of tax	$	3,934		$	2,958			$	10,023		$	9,125

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 27,		September 28,			September 27,			September 28,
		2014		2013			2014			2013
	ESPP:

	Dividend yield	—	%	—	%		—	%		—	%
	Expected volatility	41.6	%	39.7	%		41.9	%		39.6	%
	Risk-free interest rate	0.09	%	0.13	%		0.09	%		0.12	%
	Expected term (in years)	0.81		0.81			0.66			0.66


Schedule of Unrecognized Compensation Cost, Nonvested Awards	'
	At September 27, 2014, the unrecognized stock-based compensation, adjusted for estimated forfeitures, was as follows (in thousands):


		Unrecognized Expense			Average Expected Recognition Period in years
	Stock options	$	219		0.57

	Restricted stock units	12,152			1.4

	Employee stock purchase plan	350			0.35

	Total unrecognized stock-based compensation expense	$	12,721

Net_Loss_per_Share_Tables

Net Loss per Share (Tables)	9 Months Ended
	Sep. 27, 2014
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 27,				September 28,			September 27,			September 28,
		2014				2013			2014			2013
	Numerator:

	Net loss used in computing basic and diluted net loss per share	$	(277	)		$	(10,714	)	$	(17,314	)	$	(38,894	)
	Denominator:
	Weighted-average shares used in computing basic net loss per share	56,297				54,437			55,720			54,070

	Add potentially dilutive securities	—				—			—			—

	Weighted-average shares used in computing basic and diluted net loss per share	56,297				54,437			55,720			54,070

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 27,			September 28,			September 27,		September 28,
		2014			2013			2014		2013
	Options to purchase common stock	2,675			3,577			2,981		3,917

	Restricted stock units	—			278			1		512

	Employee stock purchase plan	20			46			1		1

	Total potentially dilutive securities	2,695			3,901			2,983		4,430

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	9 Months Ended
Derivative Financial Instruments (Tables)	Sep. 27, 2014
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 27, 2014 (in thousands):


	Currency	Contract Position	Contract Amount (Local Currency)		Contract Amount (U.S. Dollars)
	Japanese Yen	Sell	1,440,176		$	13,154
	Japanese Yen	Sell	1,440,176		$	13,154
	Taiwan Dollar	Buy	(30,418	)	(1,005		)
	Korean Won	Buy	(1,819,141	)	(1,741		)
	Total USD notional amount of outstanding foreign exchange contracts				$	10,408
					$	10,408
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	'
	The location and amount of gains and losses related to non-designated derivative instruments that matured in the three and nine months ended September 27, 2014 and September 28, 2013 in the Condensed Consolidated Statements of Operations are as follows (in thousands):



			Amount of Gain (Loss) Recognized on Derivatives
			Three Months Ended						Nine Months Ended
	Derivatives Not Designated as Hedging Instruments	Location of Gain (Loss) Recognized on Derivatives	September 27, 2014			September 28, 2013				September 27, 2014		September 28, 2013
	Foreign exchange forward contracts	Other income (expense), net	$	740		$	(19	)		$	465	$	(270	)
	Foreign exchange forward contracts	Other income (expense), net	$	740		$	(19	)		$	465	$	(270	)

Basis_of_Presentation_and_Summ2

Basis of Presentation and Summary of Significant Accounting Policies (Details)	9 Months Ended
	Sep. 27, 2014
Significant Accounting Policies [Line Items]	'
Number of Weeks for Year End	'P52W
Minimum	'
Significant Accounting Policies [Line Items]	'
Number of Weeks for Year End	'P52W
Maximum	'
Significant Accounting Policies [Line Items]	'
Number of Weeks for Year End	'P53W

Concentration_of_Credit_and_Ot1

Concentration of Credit and Other Risks (Details) (Customer Concentration Risk)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Dec. 28, 2013

Sep. 27, 2014

Dec. 28, 2013

Sep. 27, 2014

Dec. 28, 2013

Sales Revenue, Goods, Net

Accounts Receivable

Intel

Micron

SK Hynix

Samsung

Customer

Major Customer 1

Major Customer 2

Major Customer 3

Concentration Risk [Line Items]

Concentration Risk, Percentage

61.90%

46.90%

50.90%

43.00%

18.90%

15.50%

18.30%

15.80%

16.60%

19.00%

14.60%

10.20%

15.60%

12.40%

18.00%

17.00%

10.80%

22.00%

21.00%

25.00%

15.00%

11.00%

Concentration Risk, Number of Customers

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Goodwill (Details) (USD $)	Sep. 27, 2014	Dec. 28, 2013
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Goodwill [Roll Forward]	'	'
Goodwill	$30,731	$30,731

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets - Finite-Lived (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Finite-lived Intangible Assets [Roll Forward]	'	'
Intangible Assets, Gross Amount	$72,636	'
Additions/Disposals	0	'
Intangible Assets, Gross Amount	72,636	'
Accumulated Amortization	22,066	'
Expense, net	15,215	'
Accumulated Amortization	37,281	'
Intangible Assets, Net	35,355	50,570
Intangible Assets Net Excluding Goodwill [Roll Forward]	'	'
Intangible Assets Net Excluding Goodwill Gross	79,536	'
Intangible Assets Net Excluding Goodwill Acquired During Period	0	'
Intangible Assets Net Excluding Goodwill Gross	79,536	'
Intangible Assets, Net (Excluding Goodwill)	42,255	57,470
Existing developed technologies	'	'
Finite-lived Intangible Assets [Roll Forward]	'	'
Intangible Assets, Gross Amount	51,248	'
Additions/Disposals	0	'
Intangible Assets, Gross Amount	51,248	'
Accumulated Amortization	18,955	'
Expense, net	13,197	'
Accumulated Amortization	32,152	'
Intangible Assets, Net	19,096	32,293
Weighted Average Useful Life	'2 years 0 months 6 days	'
Trade name	'	'
Finite-lived Intangible Assets [Roll Forward]	'	'
Intangible Assets, Gross Amount	4,388	'
Additions/Disposals	0	'
Intangible Assets, Gross Amount	4,388	'
Accumulated Amortization	530	'
Expense, net	330	'
Accumulated Amortization	860	'
Intangible Assets, Net	3,528	3,858
Weighted Average Useful Life	'8 years 0 months 6 days	'
Customer relationships	'	'
Finite-lived Intangible Assets [Roll Forward]	'	'
Intangible Assets, Gross Amount	17,000	'
Intangible Assets, Gross Amount	17,000	'
Accumulated Amortization	2,581	'
Expense, net	1,688	'
Accumulated Amortization	4,269	'
Intangible Assets, Net	12,731	14,419
Weighted Average Useful Life	'6 years 0 months 6 days	'
In-process research and development	'	'
Indefinite-lived Intangible Assets [Roll Forward]	'	'
Beginning Balance	6,900	'
Indefinite-lived Intangible Assets, Acquired During Period	0	'
Ending Balance	$6,900	'

Goodwill_and_Intangible_Assets4

Goodwill and Intangible Assets - Amortization (Details) (USD $)	9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
			Cost of Sales	Cost of Sales	Cost of Sales	Cost of Sales	Selling, general and administrative	Selling, general and administrative	Selling, general and administrative	Selling, general and administrative
			Intellectual Property	Intellectual Property	Intellectual Property	Intellectual Property	Intellectual Property	Intellectual Property	Intellectual Property	Intellectual Property
Property, Plant and Equipment [Line Items]	'	'	'	'	'	'	'	'	'	'
Amortization of Intangible Assets	$15,215	'	$4,400	$3,400	$13,200	$10,400	$700	$700	$2,000	$2,200
Finite-Lived Intangible Assets, Net, Amortization Expense, Rolling Maturity [Abstract]	'	'	'	'	'	'	'	'	'	'
2014	3,566	'	'	'	'	'	'	'	'	'
2015	12,739	'	'	'	'	'	'	'	'	'
2016	8,720	'	'	'	'	'	'	'	'	'
2017	2,551	'	'	'	'	'	'	'	'	'
2018	2,501	'	'	'	'	'	'	'	'	'
and thereafter	5,278	'	'	'	'	'	'	'	'	'
Intangible Assets, Net	$35,355	$50,570	'	'	'	'	'	'	'	'

Restructuring_Charges_Narrativ

Restructuring Charges (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

Sep. 27, 2014

Sep. 28, 2013

Sep. 27, 2014

Sep. 28, 2013

Jun. 28, 2014

Mar. 29, 2014

Sep. 27, 2014

Jun. 28, 2014

Mar. 29, 2014

Sep. 28, 2013

Mar. 30, 2013

Q1 2014 Restructuring Plan

Q1 2013 Restructuring Plan

Employee

Employee Severance and Benefits

Property and Equipment Impairment

positions

Employee Severance and Benefits

Property and Equipment Impairment

positions

Employee

Restructuring Cost and Reserve [Line Items]

Number of employees eliminated

Number of temporary positions eliminated

Restructuring charges

$28,000

$143,000

$2,084,000

$4,215,000

$2,000,000

$59,000

$1,400,000

$4,000,000

$1,300,000

Asset impairments

$600,000

$100,000

$2,700,000

Restructuring_Charges_Activiti

Restructuring Charges Activities (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013
Restructuring Reserve [Roll Forward]	'	'
Accrual at beginning of period	$138	$616
Restructuring charges	2,084	4,370
Cash payments	-1,592	-1,900
Asset Impairment Charges	-600	'
Restructuring Reserve, Settled without Cash	-2	'
Adjustment to restructuring charges	'	-157
Accrual at end of period	28	167
Employee Severance and Benefits	'	'
Restructuring Reserve [Roll Forward]	'	'
Accrual at beginning of period	138	548
Restructuring charges	1,484	1,613
Cash payments	-1,592	-1,851
Asset Impairment Charges	0	'
Restructuring Reserve, Settled without Cash	-2	'
Adjustment to restructuring charges	'	-152
Accrual at end of period	28	167
Property and Equipment Impairment	'	'
Restructuring Reserve [Roll Forward]	'	'
Accrual at beginning of period	0	0
Restructuring charges	600	2,743
Cash payments	0	-32
Asset Impairment Charges	-600	'
Restructuring Reserve, Settled without Cash	'	'
Adjustment to restructuring charges	'	-5
Accrual at end of period	0	0
Contract Termination and Other Costs	'	'
Restructuring Reserve [Roll Forward]	'	'
Accrual at beginning of period	'	68
Restructuring charges	'	14
Cash payments	'	-17
Adjustment to restructuring charges	'	0
Accrual at end of period	'	0
2013 Restructuring Plan \| Employee Severance and Benefits	'	'
Restructuring Reserve [Roll Forward]	'	'
Asset Impairment Charges	'	0
Non-cash settlements	'	9
2013 Restructuring Plan \| Property and Equipment Impairment	'	'
Restructuring Reserve [Roll Forward]	'	'
Asset Impairment Charges	'	-2,743
Non-cash settlements	'	37
2013 Restructuring Plan \| Contract Termination and Other Costs	'	'
Restructuring Reserve [Roll Forward]	'	'
Asset Impairment Charges	'	0
Non-cash settlements	'	-65
2013 Restructuring Plan \| Total	'	'
Restructuring Reserve [Roll Forward]	'	'
Asset Impairment Charges	'	-2,743
Non-cash settlements	'	($19)

Fair_Value_Details

Fair Value (Details) (USD $)	Sep. 27, 2014	Dec. 28, 2013
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	$65,103	$91,895
Total	115,190	119,838
Level 1	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total	50,087	27,943
Level 2	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total	65,103	91,895
Money market funds	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	50,087	27,943
Money market funds \| Level 1	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	50,087	27,943
Money market funds \| Level 2	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	0	0
Commercial paper	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	'	11,623
Commercial paper \| Level 1	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	'	0
Commercial paper \| Level 2	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	'	11,623
U.S. Treasuries	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	47,437	49,014
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	47,437	49,014
Agency securities (Federal)	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	17,666	31,258
Agency securities (Federal) \| Level 1	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	0	0
Agency securities (Federal) \| Level 2	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	$17,666	$31,258

Marketable_Securities_Details

Marketable Securities (Details) (USD $)	Sep. 27, 2014	Dec. 28, 2013
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$65,047	$91,875
Gross Unrealized Gains	56	34
Gross Unrealized Losses	0	-14
Fair Value	65,103	91,895
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]	'	'
Due in one year or less, Amortized Cost	45,664	'
Due after one year to five years, Amortized Cost	19,383	'
Amortized Cost	65,047	'
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]	'	'
Due in one year or less, Fair Value	45,696	'
Due after one year to five years, Fair Value	19,407	'
Fair Value	65,103	'
U.S. Treasuries	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	47,381	48,991
Gross Unrealized Gains	55	33
Gross Unrealized Losses	0	-10
Fair Value	47,436	49,014
Agency securities (Federal)	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	17,666	31,261
Gross Unrealized Gains	1	1
Gross Unrealized Losses	0	-4
Fair Value	17,667	31,258
Commercial paper	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	'	11,623
Gross Unrealized Gains	'	0
Gross Unrealized Losses	'	0
Fair Value	'	$11,623

Allowance_for_Doubtful_Account2

Allowance for Doubtful Accounts (Details) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013	Dec. 28, 2013
Allowance for Doubtful Accounts Receivable [Roll Forward]	'	'	'
Balance at beginning of period	'	$290	$265
Additions	5	0	'
Reductions	-4	-19	'
Balance at end of period	$266	$271	$265

Inventories_Details

Inventories (Details) (USD $)	Sep. 27, 2014	Dec. 28, 2013
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Inventory Disclosure [Abstract]	'	'
Raw materials	$9,988	$7,411
Work-in-progress	14,342	10,531
Finished goods	1,572	2,765
Inventory, Net	$25,902	$20,707

Warranty_Details

Warranty (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]	'	'
Beginning balance	$691	$734
Accruals	1,932	1,230
Settlements	-1,594	-930
Ending balance	$1,029	$1,034

Longlived_Assets_Longlived_Ass

Long-lived Assets Long-lived Assets (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended		1 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013	Aug. 01, 2014	Sep. 27, 2014	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013	Building	Building	Building	Machinery and equipment	Machinery and equipment	Machinery and equipment
Impaired Long-Lived Assets Held and Used [Line Items]	'	'	'	'	'	'	'	'	'	'
Impairment of Long-Lived Assets to be Disposed of	$86	$15	$829	$194	'	$300	$800	$15	$500	$194
Gain on sale	$0	$0	$0	($300)	$200	'	'	'	'	'

Longlived_Assets_Details

Long-lived Assets (Details) (USD $)	Sep. 27, 2014	Dec. 28, 2013
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Property, Plant and Equipment [Line Items]	'	'
Property Plant And Equipment Net, Excludes Construction in Progress Gross	$253,474	$252,545
Less: accumulated depreciation and amortization	-228,062	-221,346
Net long-lived assets	25,412	31,199
Construction-in-progress	1,198	3,991
Total	26,610	35,190
Building	'	'
Property, Plant and Equipment [Line Items]	'	'
Property Plant And Equipment Net, Excludes Construction in Progress Gross	0	790
Machinery and equipment	'	'
Property, Plant and Equipment [Line Items]	'	'
Property Plant And Equipment Net, Excludes Construction in Progress Gross	146,757	143,463
Computer equipment and software	'	'
Property, Plant and Equipment [Line Items]	'	'
Property Plant And Equipment Net, Excludes Construction in Progress Gross	34,352	34,547
Capital leases	'	'
Property, Plant and Equipment [Line Items]	'	'
Property Plant And Equipment Net, Excludes Construction in Progress Gross	0	866
Furniture and fixtures	'	'
Property, Plant and Equipment [Line Items]	'	'
Property Plant And Equipment Net, Excludes Construction in Progress Gross	5,444	5,495
Leasehold improvements	'	'
Property, Plant and Equipment [Line Items]	'	'
Property Plant And Equipment Net, Excludes Construction in Progress Gross	$66,921	$67,384

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Loss (Details) (USD $)	Sep. 27, 2014	Dec. 28, 2013
In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Other Comprehensive Income (Loss), Net of Tax [Abstract]	'	'
Unrealized loss on marketable securities, net of tax of $439 at September 27, 2014 and $428 at December 28, 2013, respectively	($384)	($409)
Cumulative translation adjustments	-216	160
Accumulated other comprehensive loss	-600	-249
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax	$439	$428

Restricted_Stock_Units_Details

Restricted Stock Units (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended	3 Months Ended		9 Months Ended	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013	5-May-14	Sep. 27, 2014	Mar. 29, 2014	Sep. 27, 2014	Sep. 28, 2013	Mar. 30, 2013	Sep. 27, 2014
					Restricted Stock Units	Restricted Stock Units	Restricted Stock Units	Restricted Stock Units	Equity Incentive Plan	Equity Incentive Plan	Equity Incentive Plan
					executive				Restricted Stock Units	Restricted Stock Units	Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]	'	'	'	'	'	'	'	'	'	'	'
Non-vested restricted stock units	'	'	'	'	'	'	'	'	'	'	2,929,639
Awards granted	'	'	'	'	'	'	'	'	'	'	1,900,000
Awards released	'	'	'	'	'	'	'	'	'	'	-1,175,853
Awards canceled	'	'	'	'	'	'	'	'	'	'	-255,801
Non-vested restricted stock units	'	'	'	'	'	'	'	'	'	'	3,397,985
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]	'	'	'	'	'	'	'	'	'	'	'
Weighted Average Exercise Price Non-vested restricted stock units	'	'	'	'	'	'	'	'	'	'	$5.88
Weighted Average Awards Granted fair value	'	'	'	'	'	'	'	'	'	'	$6.52
Weighted Average Awards released fair value	'	'	'	'	'	'	'	'	'	'	$6.42
Weighted Average Awards canceled fair value	'	'	'	'	'	'	'	'	'	'	$6.06
Weighted Average Exercise Price Non-vested restricted stock units	'	'	'	'	'	'	'	'	'	'	$6.04
Stock Issued During Period, Shares, New Issues	'	'	'	'	350,000	'	'	'	'	'	'
Stock Issued During Period, Shares, New Issues, Number of Recipients	'	'	'	'	7	'	'	'	'	'	'
Stock-based compensation expense	$3,934,000	$2,958,000	$10,023,000	$9,125,000	'	'	'	$400,000	'	'	'
Total fair value of restricted stock units vested during the period	'	'	'	'	'	$200,000	$7,300,000	'	$100,000	$3,400,000	'

StockBased_Compensation_Includ

Stock-Based Compensation Included in Condensed Consolidated Statement of Operations (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Total stock-based compensation	$3,934	$2,958	$10,023	$9,125
Tax effect of stock-based compensation	0	0	0	0
Total stock-based compensation, net of tax	3,934	2,958	10,023	9,125
Cost of revenues	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Total stock-based compensation	700	547	1,855	1,709
Research and development	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Total stock-based compensation	1,077	810	2,638	2,652
Selling, general and administrative	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Total stock-based compensation	$2,157	$1,601	$5,530	$4,764

StockBased_Compensation_Narrat

Stock-Based Compensation (Narrative) (Details) (Employee stock purchase plan)	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Employee stock purchase plan	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock Issued During Period, Shares, Employee Stock Purchase Plans	265,467	296,245	586,386	583,173

StockBased_Compensation_Weight

Stock-Based Compensation Weighted Average Assumptions (Details) (Employee stock purchase plan)	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Employee stock purchase plan	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility	41.60%	39.70%	41.90%	39.60%
Risk-free interest rate	0.09%	0.13%	0.09%	0.12%
Expected term (in years)	'9 months 22 days	'9 months 22 days	'7 months 28 days	'7 months 28 days

StockBased_Compensation_Unreco

Stock-Based Compensation Unrecognized Compensation Costs (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized [Abstract]	'
Total unrecognized stock-based compensation expense	$12,721
Stock options	'
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized [Abstract]	'
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Stock Options	219
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	'0 years 6 months 24 days
Restricted stock units	'
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized [Abstract]	'
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Share-based Awards Other than Options	12,152
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	'1 year 4 months 23 days
Employee stock purchase plan	'
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized [Abstract]	'
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Share-based Awards Other than Options	$350
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	'4 months 5 days

Net_Loss_per_Share_Details

Net Loss per Share (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Numerator [Abstract]	'	'	'	'
Net loss used in computing basic and diluted net loss per share	($277)	($10,714)	($17,314)	($38,894)
Denominator [Abstract]	'	'	'	'
Weighted-average shares used in computing basic net loss per share	56,297	54,437	55,720	54,070
Add potentially dilutive securities	0	0	0	0
Weighted-average shares used in computing basic and diluted net loss per share	56,297	54,437	55,720	54,070

Net_Loss_Per_Share_WeightedAve

Net Loss Per Share Weighted-Average Dilutive Securities (Details)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Total potentially dilutive securities	2,695	3,901	2,983	4,430
Options to purchase common stock	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Total potentially dilutive securities	2,675	3,577	2,981	3,917
Restricted stock units	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Total potentially dilutive securities	0	278	1	512
Employee stock purchase plan	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Total potentially dilutive securities	20	46	1	1

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Income tax benefit	$0.10	($0.10)	$0.40	($0.20)

Derivative_Financial_Instrumen2

Derivative Financial Instruments (Details) (Not Designated as Hedging Instrument, Foreign Exchange Forward)	Sep. 27, 2014	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 27, 2014	Sep. 27, 2014	Sep. 27, 2014	Sep. 27, 2014	Sep. 27, 2014
In Thousands, unless otherwise specified	USD ($)	Other Income, Net	Other Income, Net	Other Income, Net	Other Income, Net	Japanese Yen	Japanese Yen	Taiwan Dollar	Taiwan Dollar	Korean Won	Korean Won
		USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	JPY (¥)	USD ($)	TWD	USD ($)	KRW
Derivatives, Fair Value [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Derivative Asset, Notional Amount	$10,408	'	'	'	'	$13,154	¥ 1,440,176	($1,005)	-30,418	($1,741)	-1,819,141
Foreign exchange forward contracts	'	$740	($19)	$465	($270)	'	'	'	'	'	'