Infinera (INFN) 10-Q 5 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 26, 2015	Oct. 29, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 26, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Trading Symbol	INFN
Entity Registrant Name	INFINERA CORP
Entity Central Index Key	1,138,639
Current Fiscal Year End Date	--12-26
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		139,806,921

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Current assets:
Cash and cash equivalents	$ 161,103	$ 86,495
Short-term investments	126,218	239,628
Accounts receivable, net of allowance for doubtful accounts of $630 in 2015 and $38 in 2014	141,586	154,596
Inventory	169,875	146,500
Prepaid expenses and other current assets	31,780	24,636
Total current assets	630,562	651,855
Property, plant and equipment, net	98,720	81,566
Intangible assets	162,082	0
Goodwill	190,119	0
Long-term investments	51,422	59,233
Cost-method investment	14,500	14,500
Long-term restricted cash	5,319	5,460
Other non-current assets	6,867	5,402
Total assets	1,159,591	818,016
Current liabilities:
Accounts payable	69,983	61,533
Accrued expenses	35,704	26,441
Accrued compensation and related benefits	40,586	38,795
Accrued warranty	17,802	12,241
Deferred revenue	31,411	35,321
Total current liabilities	195,486	174,331
Long-term debt, net	123,222	116,894
Accrued warranty, non-current	18,939	14,799
Deferred revenue, non-current	15,368	10,758
Deferred tax liability, non-current	39,374	2,132
Other long-term liabilities	$ 14,287	$ 17,195
Commitments and contingencies (Note 12)
Stockholders’ equity:
Preferred stock, $0.001 par value Authorized shares – 25,000 and no shares issued and outstanding	$ 0	$ 0
Issued and outstanding shares – 139,785 as of September 26, 2015 and 126,160 as of December 27, 2014	140	126
Additional paid-in capital	1,289,087	1,077,225
Accumulated other comprehensive income (loss)	360	(4,618)
Accumulated deficit	(552,044)	(590,826)
Total Infinera stockholders’ equity	737,543	481,907
Noncontrolling interest	15,372	0
Total stockholders' equity	752,915	481,907
Total liabilities and stockholders’ equity	$ 1,159,591	$ 818,016

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Statement of Financial Position [Abstract]
Net of allowance for doubtful accounts	$ 630	$ 38
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Common stock, authorized shares (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	139,785,000	126,160,000
Common stock, shares outstanding (in shares)	139,785,000	126,160,000

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
Revenue:
Product	$ 202,365	$ 147,178	$ 542,190	$ 413,784
Services	30,107	26,381	84,490	67,989
Total revenue	232,472	173,559	626,680	481,773
Cost of revenue:
Cost of product	117,154	86,703	306,151	251,047
Cost of services	12,513	11,554	32,816	26,765
Total cost of revenue	129,667	98,257	338,967	277,812
Gross profit	102,805	75,302	287,713	203,961
Operating expenses:
Research and development	45,466	35,051	128,144	96,135
Sales and marketing	24,721	20,794	67,298	56,738
General and administrative	18,358	11,977	46,324	36,612
Total operating expenses	88,545	67,822	241,766	189,485
Income from operations	14,260	7,480	45,947	14,476
Other income (expense), net:
Interest income	406	373	1,371	1,046
Interest expense	(3,014)	(2,781)	(8,851)	(8,186)
Other gain (loss), net	(3,293)	(24)	1,788	(1,017)
Total other income (expense), net	(5,901)	(2,432)	(5,692)	(8,157)
Income before income taxes	8,359	5,048	40,255	6,319
Provision for (benefit from) income taxes	(151)	205	1,473	1,070
Net income	$ 8,510	$ 4,843	$ 38,782	$ 5,249
Net income per common share:
Basic (in usd per share)	$ 0.06	$ 0.04	$ 0.30	$ 0.04
Diluted (in usd per share)	$ 0.06	$ 0.04	$ 0.27	$ 0.04
Weighted average shares used in computing net income per common share:
Basic (in shares)	134,834	124,378	131,007	122,953
Diluted (in shares)	145,300	128,964	141,082	127,062

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (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 income	$ 8,510	$ 4,843	$ 38,782	$ 5,249
Other comprehensive income:
Unrealized gain (loss) on available-for-sale investments	90	(90)	279	(27)
Foreign currency translation adjustment	4,729	(473)	4,699	(142)
Tax related to available-for-sale investment	0	20	0	0
Net change in accumulated other comprehensive income	4,819	(543)	4,978	(169)
Comprehensive income	$ 13,329	$ 4,300	$ 43,760	$ 5,080

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 income	$ 38,782	$ 5,249
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22,094	19,340
Amortization of debt discount and issuance costs	6,873	6,217
Amortization of premium on investments	2,405	2,720
Stock-based compensation expense	23,868	20,847
Other (gain) loss	(448)	15
Changes in assets and liabilities:
Accounts receivable	28,838	(35,463)
Inventory	(8,901)	(9,015)
Prepaid expenses and other assets	(6,058)	(4,965)
Accounts payable	(2,339)	11,009
Accrued liabilities and other expenses	(7,196)	657
Deferred revenue	700	(4,272)
Accrued warranty	8,742	4,898
Net Cash Provided by (Used in) Operating Activities, Continuing Operations	107,360	17,237
Cash Flows from Investing Activities:
Purchase of available-for-sale investments	(126,940)	(214,272)
Proceeds from sale of available-for-sale investments	67,303	17,876
Proceeds from maturities and calls of investments	178,717	168,137
Acquisition of business, net of cash acquired	(144,445)	0
Realized gain from forward contract for business acquisition	1,053	0
Purchase of cost-method investment	0	(5,500)
Purchase of property and equipment	(26,710)	(14,364)
Change in restricted cash	127	(320)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations	(50,895)	(48,443)
Cash Flows from Financing Activities:
Proceeds from issuance of common stock	23,433	19,683
Minimum tax withholding paid on behalf of employees for net share settlement	(5,043)	(1,846)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations	18,390	17,837
Effect of exchange rate changes on cash	(247)	(97)
Net change in cash and cash equivalents	74,608	(13,466)
Cash and cash equivalents at beginning of period	86,495	124,330
Cash and cash equivalents at end of period	161,103	110,864
Supplemental disclosures of cash flow information:
Cash paid for income taxes, net of refunds	2,552	1,056
Cash paid for interest	1,317	1,313
Supplemental schedule of non-cash investing and financing activities:
Transfer of inventory to fixed assets	5,861	1,838
Stock Issued During Period, Value, Acquisitions	$ 169,507	$ 0

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	9 Months Ended
	Sep. 26, 2015
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Basis of Presentation Infinera Corporation (the "Company") prepared its interim condensed consolidated financial statements that accompany these notes in conformity with U.S. generally accepted accounting principles ("U.S. GAAP") and pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (the "SEC"), consistent in all material respects with those applied in the Company’s Annual Report on Form 10-K for the fiscal year ended December 27, 2014. The Company has made certain estimates, assumptions and judgments that can affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the condensed consolidated financial statements, as well as the reported amounts of revenue and expenses during the periods presented. Significant estimates, assumptions and judgments made by management include revenue recognition, stock-based compensation, inventory valuation, accrued warranty, fair value measurement of investments and accounting for income taxes. Other estimates, assumptions and judgments made by management include allowances for sales returns, allowances for doubtful accounts, useful life of property, plant and equipment, fair value measurement of the liability component of the Company's $150.0 million of 1.75% convertible senior notes (the "Notes"), other-than-temporary impairments and derivative instruments. Management believes that the estimates and judgments upon which they rely are reasonable based upon information available to them at the time that these estimates and judgments are made. To the extent there are material differences between these estimates and actual results, the Company’s condensed consolidated financial statements will be affected. The interim financial information is unaudited, but reflects all adjustments that are, in management’s opinion, necessary to provide a fair presentation of results for the interim periods presented. All adjustments are of a normal recurring nature. The condensed consolidated financial statements include the accounts of the Company and its wholly-owned and majority-owned subsidiaries. All intercompany balances and transactions have been eliminated. During the third quarter of 2015, the Company completed its public offer to the shareholders of Transmode AB (“Transmode”), acquiring 95.8% of the outstanding common shares and voting interest in Transmode. This acquisition was accounted for as a business combination, and accordingly, the Company has consolidated the financial results of Transmode with its financial results for the period from August 20, 2015, the date the acquisition closed. The noncontrolling interest position is reported as a separate component of consolidated equity attributable to Transmode's shareholders for the periods presented. The noncontrolling interest in the Transmode entity's net loss was not significant to the consolidated results for the periods presented and therefore has been included in net income in the Company's condensed consolidated statements of operations. The Company reclassified certain amounts reported in previous periods to conform to the current presentation. This interim information should be read in conjunction with the consolidated financial statements in the Company’s Annual Report on Form 10-K for the fiscal year ended December 27, 2014. To date, a few of the Company’s customers have accounted for a significant portion of its revenue. For the three months ended September 26, 2015 , two customers individually accounted for 26% and 16% of the Company's total revenue, respectively, and for the corresponding period in 2014, one customer individually accounted for 25% of the Company's total revenue. For the nine months ended September 26, 2015 , two customers individually accounted for 18% , and 15% of the Company's total revenue, respectively, and for the corresponding period in 2014, one customer individually accounted for 20% of the Company's total revenue. Significant Accounting Policies There have been no material changes in the Company’s significant accounting policies for the nine months ended September 26, 2015 as compare d to those disclosed in the Company’s Annual Report on Form 10-K for the fiscal year ended December 27, 2014, except for the inclusion of policies related to business combinations, amortization of intangible assets, and impairment of intangible assets and goodwill. Business Combinations The Company includes the results of operations of the businesses that it acquires as of the respective dates of acquisition. The Company allocates the fair value of the purchase price of its acquisitions to the tangible assets acquired, liabilities assumed and intangible assets acquired, based on their estimated fair values. The excess of the purchase price over the fair values of these identifiable assets and liabilities is recorded as goodwill. Additional information existing as of the acquisition date but unknown to the Company may become known during the remainder of the measurement period, not to exceed 12 months from the acquisition date, which may result in changes to the amounts and allocations recorded. Amortization of Intangible Assets Intangible assets with finite lives are carried at cost, less accumulated amortization. Amortization is computed over the estimated useful lives of the respective assets. In-process research and development represents the fair value of incomplete research and development projects that have not reached technological feasibility as of the date of acquisition. Initially, these assets are not subject to amortization. Once projects have been completed they are transferred to developed technology, which are subject to amortization, while assets related to projects that have been abandoned are impaired and expensed to research and development. Impairment of Intangible Assets and Goodwill Goodwill is evaluated for impairment on an annual basis, in the fourth quarter of the Company's fiscal year, and whenever events or changes in circumstances indicate the carrying amount of goodwill may not be recoverable. The Company has elected to first assess qualitative factors to determine whether it is more likely than not that the fair value of its single reporting unit is less than its carrying amount. If the Company determines that it is more likely than not that the fair value of its single reporting unit is less than its carrying amount, then the two-step goodwill impairment test will be performed. The first step, identifying a potential impairment, compares the fair value of its single reporting unit with its carrying amount. If the carrying amount exceeds its fair value, the second step will be performed; otherwise, no further step is required. The second step, measuring the impairment loss, compares the implied fair value of the goodwill with the carrying amount of the goodwill. Any excess of the goodwill carrying amount over the implied fair value is recognized as an impairment loss. The Company evaluates events and changes in circumstances that could indicate carrying amounts of purchased intangible assets may not be recoverable. When such events or changes in circumstances occur, the Company assesses the recoverability of these assets by determining whether or not the carrying amount will be recovered through undiscounted expected future cash flows. If the total of the future undiscounted cash flows is less than the carrying amount of an asset, the Company records an impairment loss for the amount by which the carrying amount of the asset exceeds the fair value of the asset.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 26, 2015
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In September 2015, the Financial Accounting Standards Board (the "FASB") issued Accounting Standards Update 2015-16, "Business Combinations and Simplifying the Accounting for Measurement-Period Adjustments" ("ASU 2015-16"), which eliminates the requirement for an acquirer in a business combination to account for measurement-period adjustments retrospectively. Instead, an acquirer will recognize a measurement-period adjustment during the period in which it determines the amount of the adjustment. The guidance is effective for the Company in its first quarter of fiscal 2016. The Company is currently evaluating the impact of the pending adoption of ASU 2015-16 on its consolidated financial statements. In July 2015, the FASB issued Accounting Standards Update 2015-11, "Simplifying the Measurement of Inventory" ("ASU 2015-11"), to simplify the guidance on the subsequent measurement of inventory, excluding inventory measured using last-in, first-out or the retail inventory method. Under ASU 2015-11, inventory should be at the lower of cost and net realizable value. The new accounting guidance is effective for the Company in its first quarter of fiscal 2017 with early adoption permitted. The Company is currently evaluating the impact of the pending adoption of ASU 2015-11 on its consolidated financial statements. In April 2015, the FASB issued Accounting Standards Update 2015-03, "Simplifying the Presentation of Debt Issuance Costs" ("ASU 2015-03"), which changes the presentation of debt issuance costs in financial statements. ASU 2015-03 requires an entity to present such costs in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the costs will continue to be reported as interest expense. ASU 2015-03 will be effective for the Company in its first quarter of fiscal 2016. Early adoption is permitted. Other than requiring the change in balance sheet presentation, the Company does not anticipate material impacts on its consolidated financial statements upon adoption. In May 2014, the FASB issued Accounting Standards Update 2014-09, "Revenue from Contracts from Customers" ("ASU 2014-09"). ASU 2014-09 provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. ASU 2014-09 will require an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update creates a five-step model that requires entities to exercise judgment when considering the terms of the contract(s), which include (i) identifying the contract(s) with the customer; (ii) identifying the separate performance obligations in the contract; (iii) determining the transaction price; (iv) allocating the transaction price to the separate performance obligations; and (v) recognizing revenue when each performance obligation is satisfied. In July 2015, the FASB deferred the effective date for annual reporting periods beginning after December 15, 2017 (including interim reporting periods within those periods). Early adoption is permitted to the original effective date of December 15, 2016 (including interim reporting periods within those periods). ASU 2014-09 will be effective for the Company’s first quarter of 2018. The Company has the option to apply the provisions of ASU 2014-09 either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of applying this ASU recognized at the date of initial application. The Company is currently evaluating the method and impact the adoption of ASU 2014-09 will have on its consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 26, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Pursuant to the accounting guidance for fair value measurements and its subsequent updates, fair value is defined as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, the Company considers the principal or most advantageous market in which it would transact and it considers assumptions that market participants would use when pricing the asset or liability. Valuation techniques used by the Company are based upon observable and unobservable inputs. Observable or market inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s assumptions about market participant assumptions based on the best information available. Observable inputs are the preferred source of values. These two types of inputs create the following fair value hierarchy: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Prices or valuations that require management inputs that are both significant to the fair value measurement and unobservable. The Company measures its cash equivalents, foreign currency exchange forward contracts and marketable debt securities at fair value and classifies its investments in accordance with the fair value hierarchy. The Company’s money market funds and U.S. treasuries are classified within Level 1 of the fair value hierarchy and are valued based on quoted prices in active markets for identical securities. The Company classifies its certificates of deposit, commercial paper, corporate bonds and foreign currency exchange forward contracts within Level 2 of the fair value hierarchy as follows: Certificates of Deposit The Company reviews market pricing and other observable market inputs for the same or similar securities obtained from a number of industry standard data providers. In the event that a transaction is observed for the same or similar security in the marketplace, the price on that transaction reflects the market price and fair value on that day. In the absence of any observable market transactions for a particular security, the fair market value at period end would be equal to the par value. These inputs represent quoted prices for similar assets or these inputs have been derived from observable market data. Commercial Paper The Company reviews market pricing and other observable market inputs for the same or similar securities obtained from a number of industry standard data providers. In the event that a transaction is observed for the same or similar security in the marketplace, the price on that transaction reflects the market price and fair value on that day and then follows a revised accretion schedule to determine the fair market value at period end. In the absence of any observable market transactions for a particular security, the fair market value at period end is derived by accreting from the last observable market price. These inputs represent quoted prices for similar assets or these inputs have been derived from observable market data accreted mathematically to par. Corporate Bonds The Company reviews trading activity and pricing for each of the corporate bond securities in its portfolio as of the measurement date and determines if pricing data of sufficient frequency and volume in an active market exists in order to support Level 1 classification of these securities. If sufficient quoted pricing for identical securities is not available, the Company obtains market pricing and other observable market inputs for similar securities from a number of industry standard data providers. In instances where multiple prices exist for similar securities, these prices are used as inputs into a distribution-curve to determine the fair market value at period end. Foreign Currency Exchange Forward Contracts As discussed in Note 5, "Derivative Instruments" to the Notes to Condensed Consolidated Financial Statements, the Company mainly holds non-speculative foreign exchange forward contracts to hedge certain foreign currency exchange exposures. The Company estimates the fair values of derivatives based on quoted market prices or pricing models using current market rates. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs including interest rate curves, credit risk, foreign exchange rates, and forward and spot prices for currencies. The following tables represent the Company’s fair value hierarchy for its assets and liabilities measured at fair value on a recurring basis (in thousands): As of September 26, 2015 As of December 27, 2014 Fair Value Measured Using Fair Value Measured Using Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Money market funds $ 29,694 $ — $ — $ 29,694 $ 21,478 $ — $ — $ 21,478 Certificates of deposit — 7,305 — 7,305 — 8,060 — 8,060 Commercial paper — 13,662 — 13,662 — 46,072 — 46,072 Corporate bonds — 170,335 — 170,335 — 235,285 — 235,285 U.S. treasuries — — — — 14,810 — — 14,810 Foreign currency exchange forward contracts — 29 — 29 — — — — Total assets $ 29,694 $ 191,331 $ — $ 221,025 $ 36,288 $ 289,417 $ — $ 325,705 Liabilities Foreign currency exchange forward contracts $ — $ (74 ) $ — $ (74 ) $ — $ (64 ) $ — $ (64 ) During the three and nine months ended September 26, 2015, there were no transfers of assets or liabilities between Level 1 and Level 2 of the fair value hierarchy. Investments at fair value were as follows (in thousands): September 26, 2015 Adjusted Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 29,694 $ — $ — $ 29,694 Certificates of deposit 7,300 5 — 7,305 Commercial paper 13,661 1 — 13,662 Corporate bonds 170,506 6 (177 ) 170,335 Total available-for-sale investments $ 221,161 $ 12 $ (177 ) $ 220,996 December 27, 2014 Adjusted Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 21,478 $ — $ — $ 21,478 Certificates of deposit 8,060 — — 8,060 Commercial paper 46,073 — (1 ) 46,072 Corporate bonds 235,713 2 (430 ) 235,285 U.S. treasuries 14,825 1 (16 ) 14,810 Total available-for-sale investments $ 326,149 $ 3 $ (447 ) $ 325,705 As of September 26, 2015 , the Company’s available-for-sale investments in certificates of deposit, commercial paper and corporate bonds have a contractual maturity term of up to 23 months . Gross realized gains and losses on short-term and long-term investments for the three and nine months ended September 26, 2015 and September 27, 2014 were insignificant in all periods. The specific identification method is used to account for gains and losses on available-for-sale investments. As of September 26, 2015 and December 27, 2014, the Company held $117.7 million and $59.7 million of cash in banks, respectively, excluding restricted cash.

Cost-method Investment

Cost-method Investment	9 Months Ended
	Sep. 26, 2015
Investments, All Other Investments [Abstract]
Cost-method Investment	Cost-method Investment As of September 26, 2015 , the Company had an investment of $14.5 million in a privately-held company. This investment is accounted for as a cost-method investment as the Company owns less than 20% of the voting securities and does not have the ability to exercise significant influence over operating and financial policies of the entity. This investment is carried at historical cost in the Company's condensed consolidated financial statements. The Company regularly evaluates the carrying value of this cost-method investment for impairment. If the Company believes that the carrying value of the cost basis investment is in excess of estimated fair value, the Company’s policy is to record an impairment charge in other income (expense), net, in the accompanying condensed consolidated statements of operations to adjust the carrying value to estimated fair value, when the impairment is deemed other-than-temporary. As of September 26, 2015 , no event had occurred that would adversely affect the carrying value of this investment and thus no impairment charges have been recorded for this cost-method investment.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 26, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Foreign Currency Exchange Forward Contracts The Company enters into foreign currency exchange forward contracts to manage its exposure to fluctuations in foreign exchange rates that arise primarily from its euro and British pound denominated receivables and euro denominated restricted cash balance amounts that are pledged as collateral for certain stand-by and commercial letters of credit. Gains and losses on these contracts are intended to offset the impact of foreign exchange rate fluctuations on the underlying foreign currency denominated accounts receivables and restricted cash, and therefore, do not subject the Company to material balance sheet risk. These forward contracts entered into during the three and nine months ended September 26, 2015 were denominated in euros and British pounds, and had maturities of no more than 1 year . The contracts are settled for U.S. dollars and Swedish kronor ("SEK") at maturity and at rates agreed to at inception of the contracts. In April 2015, the Company entered into a foreign currency exchange forward contract with a notional amount of SEK 831 million ( $95.3 million ) to hedge currency exposures associated with the cash consideration of the offer to acquire Transmode. In July 2015, the Company entered into a series of additional foreign currency exchange option contracts to purchase up to an additional SEK 1.3 billion ( $153.8 million ) and to sell up to SEK 650 million ( $76.9 million ), which achieves the economic equivalent of a “participating forward” in order to hedge the anticipated foreign currency cash outflows associated with the additional cash consideration related to the enhanced offer to acquire the shares of Transmode. As these contracts are not formally designated as hedges, the gains and losses were recognized in the statement of operations. For the three and nine months ended September 26, 2015, the Company recorded a loss of $3.2 million and a realized gain of $1.6 million , respectively, which was included in other gain (loss), net, in the accompanying condensed consolidated statements of operations. For the three months ended September 26, 2015 and September 27, 2014, the before-tax effect of the foreign currency exchange forward contracts related to the euro and British pound denominated receivables were gains of $0.3 million and $1.2 million , respectively, and for the nine months ended September 26, 2015 and September 27, 2014, losses of $3.1 million and $0.8 million , respectively. In each of these periods, the impact of the gross gains and losses were offset by foreign exchange rate fluctuations on the underlying foreign currency denominated amounts. The Company did not designate foreign currency exchange forward contracts as hedges for accounting purposes and accordingly, changes in the fair value are recorded in other gain (loss), net, in the accompanying condensed consolidated statements of operations. These contracts were with two high-quality institutions and the Company consistently monitors the creditworthiness of the counterparties. The fair value of derivative instruments in the Company’s condensed consolidated balance sheets was as follows (in thousands): As of September 26, 2015 As of December 27, 2014 Gross Notional (1) Prepaid Expense and Other Assets Other Accrued Liabilities Gross Notional (1) Other Accrued Liabilities Foreign currency exchange forward contracts Related to euro denominated receivables $ 33,919 $ 16 $ (74 ) $ 34,445 $ (53 ) Related to British pound denominated receivables 7,340 10 — 2,678 (9 ) Related to restricted cash 258 3 — 1,236 (2 ) $ 41,517 $ 29 $ (74 ) $ 38,359 $ (64 ) (1) Represents the face amounts of forward contracts that were outstanding as of the period noted.

Business Combination

Business Combination	9 Months Ended
	Sep. 26, 2015
Business Combinations [Abstract]
Business Combination	Business Combination On August 20, 2015 (the "Acquisition Date”), the Company completed its public offer to the shareholders of Transmode, acquiring 95.8% of the outstanding common shares and voting interest in Transmode. Transmode is a metro packet-optical networking company based in Stockholm, Sweden. In August 2015, the Company initiated compulsory acquisition proceedings in accordance with Swedish law (the "Squeeze-out Proceedings") in order to acquire the remaining 4.2% or 1.2 million Transmode shares not tendered through the end of the offer period. As of the Acquisition Date, the fair value of the noncontrolling interest was approximately $15.4 million , which was based on the implied enterprise value of Transmode at the Acquisition Date. The Squeeze-out Proceedings are expected to be completed during 2016. The Company has accounted for this transaction as a business combination in exchange for total consideration of approximately $350.6 million , which consisted of the following (in thousands, except shares): Cash $ 181,133 Common stock (7,873,055 shares) 169,507 Total $ 350,640 The fair value of the 7.9 million shares of common stock issued was determined based on the closing market price of the Company’s common stock on the acquisition date. The Company expensed acquisition-related costs in the amount of $3.9 million and $6.7 million in operating expenses for the three and nine months ended September 26, 2015, respectively. The Company allocated the fair value of the purchase price of the acquisition to the tangible and intangible assets acquired as well as liabilities assumed, based on their estimated fair values. The excess of the purchase price over the fair values of these identifiable assets and liabilities was recorded as goodwill. The following table summarizes the Company’s allocation of the purchase consideration based on the fair value of assets acquired and liabilities assumed at the Acquisition Date (in thousands): Cash $ 36,688 Accounts receivable 16,183 Inventory 19,886 Other assets 8,320 Intangible assets, net 161,845 Goodwill 187,220 Current liabilities (24,320 ) Long-term liabilities (39,810 ) Noncontrolling interest (15,372 ) Total net assets $ 350,640 Long-term liabilities include $39.2 million of long-term deferred tax liabilities recorded in connection with the acquisition. The following table presents details of the identified intangible assets acquired at the Acquisition Date (in thousands): Fair Value Estimated Useful Life (Years) Trade name $ 234 0.5 Customer relationships 49,033 8 Developed technology 92,450 5 In-process technology 20,128 N/A Total $ 161,845 Goodwill generated from this business combination is primarily attributable to the synergies from combining the operations of Transmode with that of the Company, which resulted in expanded selling opportunities of both metro and long-haul solutions. The goodwill recognized is not tax deductible for Swedish income tax purposes. The amounts of revenue and net loss of Transmode included in the Company’s condensed consolidated statement of operations from the Acquisition Date to September 26, 2015 were $14.2 million and $4.0 million , respectively. The following table presents the unaudited pro forma financial information for the three and nine months ended September 26, 2015 and September 27, 2014, as though the companies were combined as of December 29, 2013 (in thousands): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Revenue $ 250,811 $ 201,406 $ 716,783 $ 582,978 Net income (loss) $ 13,872 $ (1,200 ) $ 44,633 $ (24,388 )

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 The gross carrying amount of goodwill and intangible assets and the related amortization expense of intangible assets may change due to the effects of foreign currency fluctuations as a result of acquiring an international business. Additional information existing as of the Acquisition Date but unknown to the Company may become known during the remainder of the measurement period, not to exceed 12 months from the Acquisition Date, which may result in changes to the amounts and allocations recorded. Goodwill Goodwill is recorded when the purchase price of an acquisition exceeds the fair value of the net tangible and identified intangible assets acquired. The following table presents details of the Company’s goodwill during the nine months ended September 26, 2015 (in thousands): Balance as of December 27, 2014 $ — Goodwill acquired, including translation adjustment 190,119 Accumulated impairment loss — Balance as of September 26, 2015 $ 190,119 Intangible Assets The following tables present details of the Company’s intangible assets as of September 26, 2015 (in thousands): September 26, 2015 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Intangible assets with finite lives: Trade names $ 238 $ (48 ) $ 190 Customer relationships 49,793 (633 ) 49,160 Developed technology 93,881 (1,909 ) 91,972 Other intangible assets 819 (499 ) 320 Total intangible assets with finite lives $ 144,731 $ (3,089 ) $ 141,642 In-process technology 20,440 — 20,440 Total intangible assets $ 165,171 $ (3,089 ) $ 162,082 Other intangible assets in the above table relate an acquisition completed in a previous year. Amortization expense was $2.6 million for the three and nine months ended September 26, 2015. Intangible assets are carried at cost less accumulated amortization. Amortization expenses are recorded to the appropriate cost and expense categories. The following table summarizes the Company’s estimated future amortization expense of intangible assets with finite lives by type as of September 26, 2015 (in thousands): Fiscal Years Remainder of 2015 2016 2017 2018 2019 2020 and Thereafter Total future amortization expense $ 6,428 $ 25,302 $ 25,233 $ 25,233 $ 25,233 $ 34,213

Balance Sheet Details

Balance Sheet Details	9 Months Ended
	Sep. 26, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Details	Balance Sheet Details The following table provides details of selected balance sheet items (in thousands): September 26, 2015 December 27, 2014 Inventory: Raw materials $ 24,234 $ 15,169 Work in process 48,464 50,046 Finished goods (1) 97,177 81,285 Total inventory $ 169,875 $ 146,500 Property, plant and equipment, net: Computer hardware $ 10,632 $ 8,785 Computer software (2) 20,200 17,684 Laboratory and manufacturing equipment 182,363 162,004 Furniture and fixtures 1,741 1,340 Leasehold improvements 38,505 37,825 Construction in progress 22,201 14,726 Subtotal $ 275,642 $ 242,364 Less accumulated depreciation and amortization (176,922 ) (160,798 ) Total property, plant and equipment, net $ 98,720 $ 81,566 Accrued expenses: Loss contingency related to non-cancelable purchase commitments $ 6,437 $ 5,390 Professional and other consulting fees 4,446 1,831 Taxes payable 3,085 3,993 Royalties 3,716 2,648 Accrued rebate and customer prepay liability 1,973 941 Accrued interest on convertible senior notes 901 219 Other accrued expenses 15,146 11,419 Total accrued expenses $ 35,704 $ 26,441 (1) Included in finished goods inventory at September 26, 2015 and December 27, 2014 were $8.0 million and $10.2 million , respectively, of inventory at customer locations for which product acceptance had not occurred. (2) Included in computer software at September 26, 2015 and December 27, 2014 were $7.9 million and $7.9 million , respectively, related to an enterprise resource planning ("ERP") system that the Company implemented during 2012. The unamortized ERP costs at September 26, 2015 and December 27, 2014 were $4.3 million and $5.2 million , respectively. Restricted Cash The Company’s long-term restricted cash balance is primarily comprised of certificates of deposit and money market funds, of which the majority is not insured by the Federal Deposit Insurance Corporation. These amounts primarily collateralize the Company’s issuances of stand-by letters of credit. The following table sets forth the Company's restricted cash (in thousands): September 26, 2015 December 27, 2014 Restricted cash related to outstanding stand-by letters of credit Value added tax license $ 1,372 $ 1,309 Customer proposal guarantee 2,858 3,074 Property leases 699 699 Other restricted cash 390 378 Total restricted cash $ 5,319 $ 5,460

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 26, 2015
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Other comprehensive income (loss) includes certain changes in equity that are excluded from net income. The following table sets forth the changes in accumulated other comprehensive income by component for the nine months ended September 26, 2015 (in thousands): Unrealized Gain (Loss) on Other Available-for-Sale Securities Foreign Currency Translation Accumulated Tax Effect Total Balance at December 27, 2014 $ (444 ) $ (3,414 ) $ (760 ) $ (4,618 ) Net current-period other comprehensive income 279 4,699 — 4,978 Balance at September 26, 2015 $ (165 ) $ 1,285 $ (760 ) $ 360

Basic and Diluted Net Income Pe

Basic and Diluted Net Income Per Common Share	9 Months Ended
	Sep. 26, 2015
Earnings Per Share [Abstract]
Basic and Diluted Net Income Per Common Share	Basic and Diluted Net Income Per Common Share Basic net income per common share is computed by dividing net income by the weighted average number of common shares outstanding during the period. Diluted net income per common share is computed using net income and the weighted average number of common shares outstanding plus potentially dilutive common shares outstanding during the period. Potentially dilutive common shares include the assumed exercise of outstanding stock options, assumed release of outstanding restricted stock units ("RSUs") and performance stock units ("PSUs"), assumed conversion of the Notes from the conversion spread (as discussed in Note 11, "Convertible Senior Notes"), and assumed issuance of common stock under the Company’s employee stock purchase plan ("ESPP") using the treasury stock method. The Company includes the common shares underlying PSUs in the calculation of diluted net income per share only when they become contingently issuable. In net loss periods, these potentially diluted common shares have been excluded from the diluted net loss calculation. The following table sets forth the computation of net income per common share – basic and diluted (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Numerator: Net income $ 8,510 $ 4,843 $ 38,782 $ 5,249 Denominator: Basic weighted average common shares outstanding 134,834 124,378 131,007 122,953 Effect of dilutive securities: Employee equity plans 5,397 4,586 5,911 4,109 Assumed conversion of convertible senior notes from conversion spread 5,069 — 4,164 — Diluted weighted average common shares outstanding 145,300 128,964 141,082 127,062 Net income per common share Basic $ 0.06 $ 0.04 $ 0.30 $ 0.04 Diluted $ 0.06 $ 0.04 $ 0.27 $ 0.04 During the three and nine months ended September 26, 2015, the Company included the dilutive effects of the Notes in the calculation of diluted net income per common share as the average market price was above the conversion price of the Notes. The dilutive impact of the Notes was based on the difference between the Company's average stock price during the period and the conversion price of the Notes. In the three and nine months ended September 27, 2014, the Company excluded the potential shares issuable upon conversion of the Notes in the calculation of diluted earnings per share because the market price was below the conversion price. Upon conversion of the Notes, it is the Company’s intention to pay cash equal to the lesser of the aggregate principal amount or the conversion value of the Notes being converted, therefore, only the conversion spread relating to the Notes would be included in the Company’s diluted earnings per share calculation unless their effect is anti-dilutive. The effects of certain potentially outstanding shares were not included in the calculation of diluted net income per share for the three and nine months ended September 26, 2015 and September 27, 2014 because their effect were anti-dilutive under the treasury stock method or the performance condition of the award had not been met. The following sets forth the potentially dilutive shares excluded from the computation of the diluted net income per share because their effect was anti-dilutive (in thousands): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Stock options 1 447 7 706 RSUs 26 68 535 250 PSUs — 185 97 185 ESPP shares 484 801 300 921 Total 511 1,501 939 2,062

Convertible Senior Notes

Convertible Senior Notes	9 Months Ended
	Sep. 26, 2015
Debt Disclosure [Abstract]
Convertible Senior Notes	Convertible Senior Notes In May 2013, the Company issued $150.0 million of 1.75% convertible senior notes due June 1, 2018. The Notes will mature on June 1, 2018, unless earlier purchased by the Company or converted. Interest is payable semi-annually in arrears on June 1 and December 1 of each year, commencing December 1, 2013. The net proceeds to the Company were approximately $144.5 million . The Notes are governed by an indenture dated as of May 30, 2013 (the "Indenture"), between the Company, as issuer, and U.S. Bank National Association, as trustee. The Notes are unsecured and do not contain any financial covenants or any restrictions on the payment of dividends, the incurrence of senior debt or other indebtedness, or the issuance or repurchase of securities by the Company. Upon conversion, it is the Company’s intention to pay cash equal to the lesser of the aggregate principal amount or the conversion value of the Notes as cash, shares of common stock or a combination of cash and shares of common stock, at the Company’s election, for any remaining conversion obligation. The initial conversion rate is 79.4834 shares of common stock per $1,000 principal amount of Notes, subject to anti-dilution adjustments. The initial conversion price is approximately $12.58 per share of common stock. Throughout the term of the Notes, the conversion rate may be adjusted upon the occurrence of certain events, including for any cash dividends. Holders of the Notes will not receive any cash payment representing accrued and unpaid interest upon conversion of a Note. Accrued but unpaid interest will be deemed to be paid in full upon conversion rather than canceled, extinguished or forfeited. Holders may convert their Notes under the following circumstances: • during any fiscal quarter commencing after the fiscal quarter ended on September 28, 2013 (and only during such fiscal quarter) if the last reported sale price of the common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price on each applicable trading day; • during the five business day period after any five consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; • upon the occurrence of specified corporate events described under the Indenture, such as a consolidation, merger or binding share exchange; or • at any time on or after December 1, 2017 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their Notes at any time, regardless of the foregoing circumstances. If the Company undergoes a fundamental change as defined in the Indenture governing the Notes, holders may require the Company to repurchase for cash all or any portion of their Notes at a repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, upon the occurrence of a “make-whole fundamental change” (as defined in the Indenture), the Company may, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its Notes in connection with such make-whole fundamental change. The net carrying amounts of the debt obligation were as follows (in thousands): September 26, 2015 December 27, 2014 Principal $ 150,000 $ 150,000 Unamortized discount (1) (26,778 ) (33,106 ) Total long-term debt, net $ 123,222 $ 116,894 Unamortized issuance cost (1) (2,304 ) (2,848 ) Net carrying amount $ 120,918 $ 114,046 (1) Unamortized debt conversion discount and issuance costs will be amortized over the remaining life of the Notes, which is approximately three years. In accounting for the issuance of the Notes, the Company separated the Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount ("debt discount") is amortized to interest expense over the term of the Notes. As of September 26, 2015 and December 27, 2014, the carrying amount of the equity component was $43.3 million , which represents the equity component of the debt discount related to the value of the conversion option of $45.0 million , net of the debt issuance costs attributable to the equity component of $1.7 million . In accounting for the issuance costs of $5.5 million related to the Notes, the Company allocated the total amount incurred to the liability and equity components of the Notes based on their relative values. Issuance costs attributable to the liability component were recorded as other non-current assets and will be amortized to interest expense over the term of the Notes. The issuance costs attributable to the equity component were netted with the equity component in stockholders’ equity. Additionally, the Company initially recorded a deferred tax liability of $17.0 million in connection with the issuance of the Notes, and a corresponding reduction in valuation allowance. The impact of both was recorded to stockholders’ equity. The Company determined that the embedded conversion option in the Notes does not require separate accounting treatment as a derivative instrument because it is both indexed to the Company’s own stock and would be classified in stockholder’s equity if freestanding. The following table sets forth total interest expense recognized related to the Notes (in thousands): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Contractual interest expense $ 656 $ 656 $ 1,969 $ 1,969 Amortization of debt issuance costs 186 169 544 493 Amortization of debt discount 2,162 1,956 6,328 5,724 Total interest expense $ 3,004 $ 2,781 $ 8,841 $ 8,186 The coupon rate was 1.75% . For the three and nine months ended September 26, 2015 and September 27, 2014 , the debt discount and debt issuance costs are amortized, using an annual effective interest rate of 10.23% , to interest expense over the term of the Notes. As of September 26, 2015 , the fair value of the Notes was $250.5 million . The fair value was determined based on the quoted bid price of the Notes in an over-the-counter market on September 25, 2015. The Notes are classified as Level 2 of the fair value hierarchy. During the three months ended September 26, 2015 , the closing price of the Company's common stock exceeded 130% of the applicable conversion price of the Notes on at least 20 of the last 30 consecutive trading days of the quarter; therefore, holders of the Notes may convert their notes during the three months ending December 26, 2015. Should the closing price conditions be met during the 30 consecutive trading days prior to the end of the fourth quarter of 2015 or a future quarter, the Notes will be convertible at their holders’ option during the immediately following quarter. Based on the closing price of the Company’s common stock of $20.11 on September 25, 2015, the if-converted value of the Notes exceeded their principal amount by approximately $89.8 million .

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 26, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company leases facilities under non-cancelable operating lease agreements. These leases have varying terms that range from one to ten years, predominantly no longer than ten years each and contain leasehold improvement incentives, rent holidays and escalation clauses. In addition, some of these leases have renewal options for up to five years . The Company has contractual commitments to remove leasehold improvements and return certain properties to a specified condition when the leases terminate. At the inception of a lease with such conditions, the Company records an asset retirement obligation liability and a corresponding capital asset in an amount equal to the estimated fair value of the obligation. Asset retirement obligations were $2.8 million and $2.7 million as of September 26, 2015 and December 27, 2014, respectively. These obligations are classified as other long-term liabilities on the accompanying condensed consolidated balance sheets. The Company recognizes rent expense on a straight-line basis over the lease period factoring in leasehold improvement incentives, rent holidays and escalation clauses. Rent expense for all leases was $2.3 million and $6.0 million , respectively, for the three and nine months ended September 26, 2015 and $1.8 million and $5.4 million , respectively, for the three and nine months ended September 27, 2014. The Company did not have any sublease rental income for the three and nine months ended September 26, 2015 and September 27, 2014. Future annual minimum operating lease payments at September 26, 2015 were as follows (in thousands): 2015 2016 2017 2018 2019 Thereafter Total Operating lease payments $ 2,492 $ 10,628 $ 10,277 $ 9,783 $ 8,871 $ 10,857 $ 52,908 Purchase Commitments The Company has service agreements with its major production suppliers, where the Company is committed to purchase certain parts. These obligations are typically less than the Company’s purchase needs. As of September 26, 2015 and December 27, 2014, these non-cancelable purchase commitments were $107.6 million and $128.3 million , respectively. Future purchase commitments at September 26, 2015 were as follows (in thousands): 2015 2016 2017 2018 2019 Thereafter Total Purchase commitments $ 103,834 $ 3,750 $ — $ — $ — $ — $ 107,584 The contractual obligation tables above exclude tax liabilities of $2.6 million related to uncertain tax positions because the Company is unable to determine the timing of settlement, if any, of these future payments with a reasonably reliable estimate. Indemnification Obligations From time to time, the Company enters into certain types of contracts that contingently require it to indemnify parties against third party claims. These contracts primarily relate to: (i) certain real estate leases under which the Company may be required to indemnify property owners for environmental and other liabilities, and other claims arising from the Company’s use of the applicable premises; (ii) certain agreements with the Company’s officers, directors and certain key employees, under which the Company may be required to indemnify such persons for liabilities; and (iii) certain provisions in the Company’s customer agreements that may require the Company to indemnify their customers and their affiliated parties against certain liabilities, including if the Company’s products infringe a third party’s intellectual property rights. The terms of such indemnification obligations vary. Because the maximum obligated amounts under these agreements generally are not explicitly stated, the maximum potential amount of future payments the Company could be required to make under these indemnification agreements is generally unlimited. To date, the Company has not incurred any material costs as a result of the indemnification obligations and has not accrued any liabilities related to such obligations in the Company’s consolidated financial statements. As permitted under Delaware law and the Company’s charter and bylaws, the Company has agreements whereby it indemnifies certain of its officers and each of its directors. The term of the indemnification period is for the officer’s or director’s lifetime for certain events or occurrences while the officer or director is, or was, serving at the Company’s request in such capacity. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited; however, the Company has a Director and Officer insurance policy that may reduce its exposure and enable it to recover all or a portion of any future amounts paid. As a result of its insurance policy coverage, the Company believes the estimated fair value of these indemnification agreements is minimal.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 26, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity	Stockholders’ Equity Stock-based Compensation Plans The Company has stock-based compensation plans pursuant to which the Company has granted stock options, RSUs and PSUs. The Company also has an ESPP for all eligible employees. As of September 26, 2015 , there were a total of 15.6 million shares of common stock available for grant under the Company’s 2007 Equity Incentive Plan ("2007 Plan"). The following tables summarize the Company’s equity award activity and related information (in thousands, except per share data): Number of Stock Options Weighted-Average Exercise Price Per Share Aggregate Intrinsic Value Outstanding at December 27, 2014 4,298 $ 7.29 $ 32,833 Stock options granted — $ — Stock options exercised (1,518 ) $ 7.36 $ 18,013 Stock options canceled — $ — Outstanding at September 26, 2015 2,780 $ 7.25 $ 35,768 Vested and expected to vest as of September 26, 2015 2,779 $ 35,758 Exercisable at September 26, 2015 2,756 $ 7.24 $ 35,485 The aggregate intrinsic value of unexercised stock options is calculated as the difference between the closing price of the Company’s common stock of $20.11 at September 25, 2015 and the exercise prices of the underlying stock options. The aggregate intrinsic value of the stock options that have been exercised is calculated as the difference between the fair market value of the common stock at the date of exercise and the exercise price of the underlying stock options. Number of Restricted Stock Units Weighted- Average Grant Date Fair Value Per Share Aggregate Intrinsic Value Outstanding at December 27, 2014 6,042 $ 8.14 $ 90,085 RSUs granted 1,899 $ 18.41 RSUs released (2,883 ) $ 7.78 $ 50,734 RSUs canceled (227 ) $ 10.55 Outstanding at September 26, 2015 4,831 $ 12.28 $ 97,155 Expected to vest at September 26, 2015 4,608 $ 92,675 Number of Performance Stock Units Weighted- Average Grant Date Fair Value Per Share Aggregate Intrinsic Value Outstanding at December 27, 2014 876 $ 7.49 $ 13,067 PSUs granted 309 $ 18.15 PSUs performance earned (1) 129 $ 7.32 PSUs released (413 ) $ 7.00 $ 7,231 PSUs canceled (193 ) $ 8.03 Outstanding at September 26, 2015 708 $ 12.12 $ 14,244 Expected to vest at September 26, 2015 686 $ 13,794 (1) Represents the additional PSUs awarded resulting from the achievement of performance goals above the performance targets established at grant. The aggregate intrinsic value of unreleased RSUs and unreleased PSUs is calculated using the closing price of the Company's common stock of $20.11 at September 25, 2015. The aggregate intrinsic value of RSUs and PSUs released is calculated using the fair market value of the common stock at the date of release. The following table presents total stock-based compensation cost for instruments granted but not yet amortized, net of estimated forfeitures, of the Company’s equity compensation plans as of September 26, 2015 . These costs are expected to be amortized on a straight-line basis over the following weighted-average periods (in thousands, except for weighted-average period): Unrecognized Compensation Expense, Net Weighted- Average Period (in years) Stock options $ 83 1.5 RSUs $ 42,314 2.4 PSUs $ 4,720 1.3 Employee Stock Options The estimated values of stock options, as well as assumptions used in calculating these values were based on estimates as follows (expense amounts in thousands): Three Months Ended Nine Months Ended Employee and Director Stock Options September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Volatility N/A N/A N/A 52% Risk-free interest rate N/A N/A N/A 1.3% Expected life N/A N/A N/A 4.3 years Estimated fair value N/A N/A N/A $3.85 Total stock-based compensation expense $37 $108 $160 $623 _________________ N/A Not applicable because the Company did not grant any stock options during the period. Employee Stock Purchase Plan The fair value of the ESPP shares was estimated at the date of grant using the following assumptions (expense amounts in thousands): Three Months Ended Nine Months Ended Employee Stock Purchase Plan September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Volatility 39% 46% 39% - 53% 46% - 51% Risk-free interest rate 0.26% 0.06% 0.13% - 0.26% 0.02% - 0.11% Expected life 0.5 years 0.5 years 0.5 years 0.3 - 0.5 years Estimated fair value $6.43 $2.54 $5.15 - $6.43 $2.05 - $2.57 Total stock-based compensation expense $1,147 $1,092 $3,275 $2,726 Restricted Stock Units During the three and nine months ended September 26, 2015 , the Company granted RSUs to employees and members of the Company’s board of directors to receive an aggregate of 0.2 million shares and 1.9 million shares of the Company’s common stock, respectively. All RSUs awarded are subject to each individual's continued service to the Company through each applicable vesting date. The Company accounted for the fair value of the RSUs using the closing market price of the Company’s common stock on the date of grant. Amortization of stock-based compensation related to RSUs in the three and nine months ended September 26, 2015 and September 27, 2014 was approximately $5.6 million and $16.7 million , respectively, and $5.6 million and $15.9 million , respectively. Performance Stock Units Pursuant to the 2007 Plan, the Company has granted PSUs to certain of the Company’s executive officers, senior management and employees. All PSUs awarded are subject to each individual's continued service to the Company through each applicable vesting date and if the performance metrics are not met within the time limits specified in the award agreements, the PSUs will be canceled. A number of PSUs granted to the Company’s executive officers and senior management are based on the total shareholder return of the Company's common stock price as compared to the total shareholder return of a designated index over the span of one year , two years and three years . The number of shares to be issued upon vesting of these PSUs range from 0 to 1.5 times the target number of PSUs granted depending on the Company’s performance against the index. The ranges of estimated values of the PSUs granted that are compared to an index, as well as the assumptions used in calculating these values were based on estimates as follows: 2015 2014 2013 Index SPGIIPTR SPGIIPTR NASDAQ Telecom Composite Index volatility 18% - 19% 25% 23% Infinera volatility 48% 49% - 50% 55% Risk-free interest rate 0.97% - 1.10% 0.66% - 0.71% 0.42% Correlation with index 0.52 0.60 0.56 Estimated fair value $18.08 - $19.29 $6.59 - $7.60 $6.27 - $7.06 In addition, certain other PSUs granted to the Company’s executive officers, senior management and certain employees will only vest upon the achievement of specific financial or operational performance criteria. The following table summarizes by grant year, the Company’s PSU activity for the nine months ended September 26, 2015 (in thousands): Total Number of Performance Stock Units 2012 2013 2014 2015 Outstanding at December 27, 2014 876 191 296 389 — PSUs granted 309 — — — 309 PSUs performance earned (1) 129 — 74 55 — PSUs released (413 ) — (223 ) (184 ) (6 ) PSUs canceled (193 ) (191 ) — — (2 ) Outstanding at September 26, 2015 708 — 147 260 301 (1) Represents the additional PSUs awarded resulting from the achievement of performance goals above the performance targets established at grant. Amortization of stock-based compensation related to PSUs in the three and nine months ended September 26, 2015 and September 27, 2014 was approximately $1.6 million and $3.8 million , respectively, and $0.6 million and $1.5 million , respectively. Stock-Based Compensation The following tables summarize the effects of stock-based compensation on the Company’s condensed consolidated balance sheets and statements of operations for the periods presented (in thousands): September 26, 2015 December 27, 2014 Stock-based compensation effects in inventory $ 3,202 $ 3,088 Stock-based compensation effects in deferred inventory cost $ 13 $ 13 Stock-based compensation effects in fixed assets $ 100 $ 119 Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Stock-based compensation effects included in net income before income taxes Cost of revenue $ 645 $ 492 $ 1,740 $ 1,421 Research and development 2,788 2,270 8,183 6,488 Sales and marketing 2,131 1,982 5,922 5,517 General and administration 1,911 1,628 5,406 4,707 $ 7,475 $ 6,372 $ 21,251 $ 18,133 Cost of revenue – amortization from balance sheet (1) 976 999 2,617 2,714 Total stock-based compensation expense $ 8,451 $ 7,371 $ 23,868 $ 20,847 (1) Stock-based compensation expense deferred to inventory and deferred inventory costs in prior periods and recognized in the current period.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 26, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Provision for (benefit from) income taxes for the three and nine months ended September 26, 2015 was $(0.2) million and $1.5 million , respectively, on pre-tax income of $8.4 million and $40.3 million , respectively. This compares to a tax provision of $0.2 million and $1.1 million , respectively, on a pre-tax income of $5.0 million and $6.3 million , respectively, for the three and nine months ended September 27, 2014. The results for the three months and nine months ended September 26, 2015 reflect purchase accounting amortization and other charges related to the acquisition of Transmode during the quarter. The amortization resulted in a decrease in pre-tax income on a consolidated basis of $6.4 million with a corresponding benefit to the tax provision of $1.4 million . In all periods, the tax expense projected in the Company's effective tax rate primarily represents foreign taxes of the Company's overseas subsidiaries compensated on a cost-plus basis, as well as the operating results of Transmode, inclusive of purchase accounting charges and amortization for the three months ended September 26, 2015. Due to the Company's significant U.S. loss carryforward position and corresponding full valuation allowance, the Company has not been subject to federal or state tax on its U.S. income because of the availability of loss carryforwards, with the exception of some state taxes for which the losses are limited by statute. The release of transfer pricing reserves in the future will have a beneficial impact to tax expense, but the timing of the impact depends on factors such as expiration of the statute of limitations or settlements with tax authorities. No significant releases are expected in the near future based on information available at this time. The Company must assess the likelihood that some portion or all of its deferred tax assets will be recovered from future taxable income within the respective jurisdictions, and to the extent the Company believes that recovery does not meet the “more-likely-than-not” standard, it must establish a valuation allowance. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management judgment is required in determining the Company's provision for income taxes, its deferred tax assets and liabilities, and any valuation allowance recorded against its net deferred tax assets. The Company has been profitable for six consecutive quarters beginning with the second quarter of fiscal 2014. Despite this trend, the Company must consider other positive and negative evidence, including the Company's forecasts of taxable income over the applicable carryforward periods, its current financial performance, its market environment, and other factors in evaluating the need for a full or partial valuation allowance against its net U.S. deferred tax assets. Management believes that it was more likely than not, that the Company would be unable to utilize those deferred tax assets in the future. Accordingly, the domestic net deferred tax assets were fully reserved with a valuation allowance. To the extent that the Company determines that deferred tax assets are realizable on a more likely than not basis, and adjustment is needed, that adjustment will be recorded in the period that the determination is made and would generally decrease the valuation allowance and result in recording a corresponding benefit to earnings.

Segment Information

Segment Information	9 Months Ended
	Sep. 26, 2015
Segment Reporting [Abstract]
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or decision making group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the Company’s Chief Executive Officer ("CEO"). The Company’s CEO reviews financial information presented on a consolidated basis, accompanied by information about revenue by geographic region for purposes of allocating resources and evaluating financial performance. The Company has one business activity. Accordingly, the Company is considered to be in a single reporting segment and operating unit structure. Revenue by geographic region is based on the shipping address of the customer. The following tables set forth revenue and long-lived assets by geographic region (in thousands): Revenue Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Americas: United States $ 158,845 $ 120,769 $ 440,610 $ 367,802 Other Americas 20,874 9,230 39,944 17,526 179,719 129,999 480,554 385,328 Europe, Middle East and Africa 41,655 34,131 114,163 78,978 Asia Pacific and Japan 11,098 9,429 31,963 17,467 Total revenue $ 232,472 $ 173,559 $ 626,680 $ 481,773 Property, plant and equipment, net September 26, 2015 December 27, 2014 United States $ 91,052 $ 79,025 Other Americas 135 196 Europe, Middle East and Africa 5,485 1,477 Asia Pacific and Japan 2,048 868 Total property, plant and equipment, net $ 98,720 $ 81,566

Guarantees

Guarantees	9 Months Ended
	Sep. 26, 2015
Guarantees [Abstract]
Guarantees	Guarantees Product Warranties The Company warrants that its products will operate substantially in conformity with product specifications. Hardware warranties provide the purchaser with protection in the event that the product does not perform to product specifications. During the warranty period, the purchaser’s sole and exclusive remedy in the event of such defect or failure to perform is limited to the correction of the defect or failure by repair, refurbishment or replacement, at the Company’s sole option and expense. The Company's hardware warranty periods range from one to five years from date of acceptance for hardware and the Company's software warranty is 90 days . Upon delivery of the Company's products, the Company provides for the estimated cost to repair or replace products that may be returned under warranty. The hardware warranty accrual is based on actual historical returns and cost of repair experience and the application of those historical rates to the Company's in-warranty installed base. The provision for warranty claims fluctuates depending upon the installed base of products and the failure rates and costs of repair associated with these products under warranty. Furthermore, the Company's costs of repair vary based on repair volume and its ability to repair, rather than replace, defective units. In the event that actual product failure rates and costs to repair differ from the Company's estimates, revisions to the warranty provision are required. In addition, from time to time, specific hardware warranty accruals may be made if unforeseen technical problems arise with specific products. The Company regularly assesses the adequacy of its recorded warranty liabilities and adjusts the amounts as necessary. Activity related to product warranty was as follows (in thousands): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Beginning balance $ 28,439 $ 27,948 $ 27,040 $ 22,908 Charges to operations 10,791 5,820 22,158 18,181 Utilization (3,515 ) (2,312 ) (8,336 ) (7,924 ) Change in estimate (1) 1,026 (3,650 ) (4,121 ) (5,359 ) Balance at the end of the period $ 36,741 $ 27,806 $ 36,741 $ 27,806 (1) The Company records hardware warranty liabilities based on the latest quality and cost information available as of that date. The changes in estimate shown here are due to changes in overall actual failure rates, the mix of new versus used units related to replacement of failed units, and changes in the estimated cost of repair. As the Company's products mature over time, failure rates and repair costs generally decline leading to favorable changes in warranty reserves.

Litigation and Contingencies

Litigation and Contingencies	9 Months Ended
	Sep. 26, 2015
Commitments and Contingencies Disclosure [Abstract]
Litigation and Contingencies	Litigation and Contingencies Legal Matters From time to time, the Company is subject to various legal proceedings, claims and litigation arising in the ordinary course of business. While the outcome of these matters is currently not determinable, the Company does not expect that the ultimate costs to resolve these matters will have a material effect on its consolidated financial position, results of operations or cash flows. Cambrian Science Patent Infringement Litigation On July 12, 2011, the Company was notified by Level 3 that Cambrian Science Corporation ("Cambrian") filed suit against Level 3 and six other defendants, including Cox Communications, Inc., XO Communications, LLC, Global Crossing Limited, 360Networks (USA), Inc., Integra Telecom, Inc. and IXC, Inc. dba Telekenex (collectively, the "Defendants") in the U.S. District Court for the Central District of California alleging infringement of patent no. 6,775,312 (the "'312 Patent") and requesting damages for such alleged infringement (the "Cambrian Claim"). The nature of the Cambrian Claim involves allegations of infringement of the '312 Patent resulting from the Defendants’ use of certain products and systems in the Defendants’ networks, including the Infinera DTN platform. On August 24, 2011, Cambrian amended the complaint to name the Company as a defendant. The Company assumed the defense of the Cambrian Claim and filed an answer to Cambrian’s complaint on September 21, 2011, in which the Company denied infringement of the '312 Patent and raised other defenses. Cambrian filed a second amended complaint on October 6, 2011, which included many of the same allegations as in the original complaint. The Company filed its answer to the second amended complaint on October 21, 2011, in which the Company maintained the same denials and defenses as in the Company’s initial answer. On December 23, 2011, the Company filed a motion requesting that the court stay the case with respect to each of the above-noted customer Defendants. Cambrian filed its opposition to the Company’s motion on December 30, 2011. The Company’s request was denied in the court’s decision on March 7, 2012. The Company presented evidence on the appropriate meanings of relevant key words used in the patent claims during a claim construction hearing on November 20, 2012. On June 17, 2013, the court issued an order regarding claim construction, in which the court agreed with almost all of the Company’s proposed claim constructions. On October 17, 2013, the parties met for a court-mandated mediation. On April 24, 2014, the Company filed two motions for summary judgment relating to non-infringement and Cambrian’s claim to an earlier date of invention. The court held a hearing on the summary judgment motions on June 9, 2014. On July 2, 2014, the court granted the Company's motion for summary judgment on non-infringement and entered a final judgment of non-infringement of the '312 Patent. On August 1, 2014, Cambrian filed a notice of appeal regarding the ruling of non-infringement to the Court of Appeals for the Federal Circuit (“CAFC”), and Cambrian’s appeal brief was filed on November 6, 2014. The Company filed its responsive brief on January 5, 2015, arguing that the CAFC should affirm the lower court’s finding of non-infringement, and on February 2, 2015, Cambrian filed their reply brief. Oral argument of this appeal took place on May 5, 2015. On June 29, 2015, the CAFC affirmed the court’s claim construction and grant of summary judgment of non-infringement. The Company has not received notice of any further filings since the CAFC affirmation and believes the judgment of non-infringement to be final. After the court had granted summary judgment in July 2014, the Company sought to recover certain costs and attorney's fees from Cambrian. The Court has taken the matter under submission and has yet to issue a final ruling on the amount of fees to be awarded to the Company. Loss Contingencies The Company is subject to the possibility of various losses arising in the ordinary course of business. These may relate to disputes, litigation and other legal actions. In the preparation of its quarterly and annual financial statements, the Company considers the likelihood of loss or the incurrence of a liability, including whether it is probable, reasonably possible or remote that a liability has been incurred, as well as the Company’s ability to reasonably estimate the amount of loss, in determining loss contingencies. In accordance with U.S. GAAP, an estimated loss contingency is accrued when it is probable that a liability has been incurred and the amount of loss can be reasonably estimated. The Company regularly evaluates current information to determine whether any accruals should be adjusted and whether new accruals are required. As of September 26, 2015, the Company has accrued the estimated liabilities associated with these potential loss contingencies.

Basis of Presentation and Sig24

Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 26, 2015
Accounting Policies [Abstract]
Business Combinations	Business Combinations The Company includes the results of operations of the businesses that it acquires as of the respective dates of acquisition. The Company allocates the fair value of the purchase price of its acquisitions to the tangible assets acquired, liabilities assumed and intangible assets acquired, based on their estimated fair values. The excess of the purchase price over the fair values of these identifiable assets and liabilities is recorded as goodwill. Additional information existing as of the acquisition date but unknown to the Company may become known during the remainder of the measurement period, not to exceed 12 months from the acquisition date, which may result in changes to the amounts and allocations recorded.
Amortization of Intangible Assets	Amortization of Intangible Assets Intangible assets with finite lives are carried at cost, less accumulated amortization. Amortization is computed over the estimated useful lives of the respective assets. In-process research and development represents the fair value of incomplete research and development projects that have not reached technological feasibility as of the date of acquisition. Initially, these assets are not subject to amortization. Once projects have been completed they are transferred to developed technology, which are subject to amortization, while assets related to projects that have been abandoned are impaired and expensed to research and development.
Impairment of Intangible Assets and Goodwill	Impairment of Intangible Assets and Goodwill Goodwill is evaluated for impairment on an annual basis, in the fourth quarter of the Company's fiscal year, and whenever events or changes in circumstances indicate the carrying amount of goodwill may not be recoverable. The Company has elected to first assess qualitative factors to determine whether it is more likely than not that the fair value of its single reporting unit is less than its carrying amount. If the Company determines that it is more likely than not that the fair value of its single reporting unit is less than its carrying amount, then the two-step goodwill impairment test will be performed. The first step, identifying a potential impairment, compares the fair value of its single reporting unit with its carrying amount. If the carrying amount exceeds its fair value, the second step will be performed; otherwise, no further step is required. The second step, measuring the impairment loss, compares the implied fair value of the goodwill with the carrying amount of the goodwill. Any excess of the goodwill carrying amount over the implied fair value is recognized as an impairment loss. The Company evaluates events and changes in circumstances that could indicate carrying amounts of purchased intangible assets may not be recoverable. When such events or changes in circumstances occur, the Company assesses the recoverability of these assets by determining whether or not the carrying amount will be recovered through undiscounted expected future cash flows. If the total of the future undiscounted cash flows is less than the carrying amount of an asset, the Company records an impairment loss for the amount by which the carrying amount of the asset exceeds the fair value of the asset.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In September 2015, the Financial Accounting Standards Board (the "FASB") issued Accounting Standards Update 2015-16, "Business Combinations and Simplifying the Accounting for Measurement-Period Adjustments" ("ASU 2015-16"), which eliminates the requirement for an acquirer in a business combination to account for measurement-period adjustments retrospectively. Instead, an acquirer will recognize a measurement-period adjustment during the period in which it determines the amount of the adjustment. The guidance is effective for the Company in its first quarter of fiscal 2016. The Company is currently evaluating the impact of the pending adoption of ASU 2015-16 on its consolidated financial statements. In July 2015, the FASB issued Accounting Standards Update 2015-11, "Simplifying the Measurement of Inventory" ("ASU 2015-11"), to simplify the guidance on the subsequent measurement of inventory, excluding inventory measured using last-in, first-out or the retail inventory method. Under ASU 2015-11, inventory should be at the lower of cost and net realizable value. The new accounting guidance is effective for the Company in its first quarter of fiscal 2017 with early adoption permitted. The Company is currently evaluating the impact of the pending adoption of ASU 2015-11 on its consolidated financial statements. In April 2015, the FASB issued Accounting Standards Update 2015-03, "Simplifying the Presentation of Debt Issuance Costs" ("ASU 2015-03"), which changes the presentation of debt issuance costs in financial statements. ASU 2015-03 requires an entity to present such costs in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the costs will continue to be reported as interest expense. ASU 2015-03 will be effective for the Company in its first quarter of fiscal 2016. Early adoption is permitted. Other than requiring the change in balance sheet presentation, the Company does not anticipate material impacts on its consolidated financial statements upon adoption. In May 2014, the FASB issued Accounting Standards Update 2014-09, "Revenue from Contracts from Customers" ("ASU 2014-09"). ASU 2014-09 provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. ASU 2014-09 will require an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update creates a five-step model that requires entities to exercise judgment when considering the terms of the contract(s), which include (i) identifying the contract(s) with the customer; (ii) identifying the separate performance obligations in the contract; (iii) determining the transaction price; (iv) allocating the transaction price to the separate performance obligations; and (v) recognizing revenue when each performance obligation is satisfied. In July 2015, the FASB deferred the effective date for annual reporting periods beginning after December 15, 2017 (including interim reporting periods within those periods). Early adoption is permitted to the original effective date of December 15, 2016 (including interim reporting periods within those periods). ASU 2014-09 will be effective for the Company’s first quarter of 2018. The Company has the option to apply the provisions of ASU 2014-09 either retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of applying this ASU recognized at the date of initial application. The Company is currently evaluating the method and impact the adoption of ASU 2014-09 will have on its consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 26, 2015
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables represent the Company’s fair value hierarchy for its assets and liabilities measured at fair value on a recurring basis (in thousands): As of September 26, 2015 As of December 27, 2014 Fair Value Measured Using Fair Value Measured Using Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Money market funds $ 29,694 $ — $ — $ 29,694 $ 21,478 $ — $ — $ 21,478 Certificates of deposit — 7,305 — 7,305 — 8,060 — 8,060 Commercial paper — 13,662 — 13,662 — 46,072 — 46,072 Corporate bonds — 170,335 — 170,335 — 235,285 — 235,285 U.S. treasuries — — — — 14,810 — — 14,810 Foreign currency exchange forward contracts — 29 — 29 — — — — Total assets $ 29,694 $ 191,331 $ — $ 221,025 $ 36,288 $ 289,417 $ — $ 325,705 Liabilities Foreign currency exchange forward contracts $ — $ (74 ) $ — $ (74 ) $ — $ (64 ) $ — $ (64 )
Investments at Fair Value	Investments at fair value were as follows (in thousands): September 26, 2015 Adjusted Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 29,694 $ — $ — $ 29,694 Certificates of deposit 7,300 5 — 7,305 Commercial paper 13,661 1 — 13,662 Corporate bonds 170,506 6 (177 ) 170,335 Total available-for-sale investments $ 221,161 $ 12 $ (177 ) $ 220,996 December 27, 2014 Adjusted Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 21,478 $ — $ — $ 21,478 Certificates of deposit 8,060 — — 8,060 Commercial paper 46,073 — (1 ) 46,072 Corporate bonds 235,713 2 (430 ) 235,285 U.S. treasuries 14,825 1 (16 ) 14,810 Total available-for-sale investments $ 326,149 $ 3 $ (447 ) $ 325,705

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 26, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments not Designated as Hedging Instruments	The fair value of derivative instruments in the Company’s condensed consolidated balance sheets was as follows (in thousands): As of September 26, 2015 As of December 27, 2014 Gross Notional (1) Prepaid Expense and Other Assets Other Accrued Liabilities Gross Notional (1) Other Accrued Liabilities Foreign currency exchange forward contracts Related to euro denominated receivables $ 33,919 $ 16 $ (74 ) $ 34,445 $ (53 ) Related to British pound denominated receivables 7,340 10 — 2,678 (9 ) Related to restricted cash 258 3 — 1,236 (2 ) $ 41,517 $ 29 $ (74 ) $ 38,359 $ (64 ) (1) Represents the face amounts of forward contracts that were outstanding as of the period noted.

Business Combination (Tables)

Business Combination (Tables)	9 Months Ended
	Sep. 26, 2015
Business Combinations [Abstract]
Schedule of Business Acquisitions by Acquisition, Equity Interest Issued or Issuable	The Company has accounted for this transaction as a business combination in exchange for total consideration of approximately $350.6 million , which consisted of the following (in thousands, except shares): Cash $ 181,133 Common stock (7,873,055 shares) 169,507 Total $ 350,640
Schedule of Business Acquisitions, by Acquisition	The following table summarizes the Company’s allocation of the purchase consideration based on the fair value of assets acquired and liabilities assumed at the Acquisition Date (in thousands): Cash $ 36,688 Accounts receivable 16,183 Inventory 19,886 Other assets 8,320 Intangible assets, net 161,845 Goodwill 187,220 Current liabilities (24,320 ) Long-term liabilities (39,810 ) Noncontrolling interest (15,372 ) Total net assets $ 350,640
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The following table presents details of the identified intangible assets acquired at the Acquisition Date (in thousands): Fair Value Estimated Useful Life (Years) Trade name $ 234 0.5 Customer relationships 49,033 8 Developed technology 92,450 5 In-process technology 20,128 N/A Total $ 161,845
Schedule of Indefinite-lived Intangible Assets Acquired as Part of Business Combination	The following table presents details of the identified intangible assets acquired at the Acquisition Date (in thousands): Fair Value Estimated Useful Life (Years) Trade name $ 234 0.5 Customer relationships 49,033 8 Developed technology 92,450 5 In-process technology 20,128 N/A Total $ 161,845
Business Acquisition, Pro Forma Information	The amounts of revenue and net loss of Transmode included in the Company’s condensed consolidated statement of operations from the Acquisition Date to September 26, 2015 were $14.2 million and $4.0 million , respectively. The following table presents the unaudited pro forma financial information for the three and nine months ended September 26, 2015 and September 27, 2014, as though the companies were combined as of December 29, 2013 (in thousands): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Revenue $ 250,811 $ 201,406 $ 716,783 $ 582,978 Net income (loss) $ 13,872 $ (1,200 ) $ 44,633 $ (24,388 )

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 26, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table presents details of the Company’s goodwill during the nine months ended September 26, 2015 (in thousands): Balance as of December 27, 2014 $ — Goodwill acquired, including translation adjustment 190,119 Accumulated impairment loss — Balance as of September 26, 2015 $ 190,119
Schedule of Finite-Lived Intangible Assets	The following tables present details of the Company’s intangible assets as of September 26, 2015 (in thousands): September 26, 2015 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Intangible assets with finite lives: Trade names $ 238 $ (48 ) $ 190 Customer relationships 49,793 (633 ) 49,160 Developed technology 93,881 (1,909 ) 91,972 Other intangible assets 819 (499 ) 320 Total intangible assets with finite lives $ 144,731 $ (3,089 ) $ 141,642 In-process technology 20,440 — 20,440 Total intangible assets $ 165,171 $ (3,089 ) $ 162,082
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The following table summarizes the Company’s estimated future amortization expense of intangible assets with finite lives by type as of September 26, 2015 (in thousands): Fiscal Years Remainder of 2015 2016 2017 2018 2019 2020 and Thereafter Total future amortization expense $ 6,428 $ 25,302 $ 25,233 $ 25,233 $ 25,233 $ 34,213

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	9 Months Ended
	Sep. 26, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Details of Selected Balance Sheet Items	The following table provides details of selected balance sheet items (in thousands): September 26, 2015 December 27, 2014 Inventory: Raw materials $ 24,234 $ 15,169 Work in process 48,464 50,046 Finished goods (1) 97,177 81,285 Total inventory $ 169,875 $ 146,500 Property, plant and equipment, net: Computer hardware $ 10,632 $ 8,785 Computer software (2) 20,200 17,684 Laboratory and manufacturing equipment 182,363 162,004 Furniture and fixtures 1,741 1,340 Leasehold improvements 38,505 37,825 Construction in progress 22,201 14,726 Subtotal $ 275,642 $ 242,364 Less accumulated depreciation and amortization (176,922 ) (160,798 ) Total property, plant and equipment, net $ 98,720 $ 81,566 Accrued expenses: Loss contingency related to non-cancelable purchase commitments $ 6,437 $ 5,390 Professional and other consulting fees 4,446 1,831 Taxes payable 3,085 3,993 Royalties 3,716 2,648 Accrued rebate and customer prepay liability 1,973 941 Accrued interest on convertible senior notes 901 219 Other accrued expenses 15,146 11,419 Total accrued expenses $ 35,704 $ 26,441 (1) Included in finished goods inventory at September 26, 2015 and December 27, 2014 were $8.0 million and $10.2 million , respectively, of inventory at customer locations for which product acceptance had not occurred. (2) Included in computer software at September 26, 2015 and December 27, 2014 were $7.9 million and $7.9 million , respectively, related to an enterprise resource planning ("ERP") system that the Company implemented during 2012. The unamortized ERP costs at September 26, 2015 and December 27, 2014 were $4.3 million and $5.2 million , respectively.
Schedule of Components of Restricted Cash	The following table sets forth the Company's restricted cash (in thousands): September 26, 2015 December 27, 2014 Restricted cash related to outstanding stand-by letters of credit Value added tax license $ 1,372 $ 1,309 Customer proposal guarantee 2,858 3,074 Property leases 699 699 Other restricted cash 390 378 Total restricted cash $ 5,319 $ 5,460

Accumulated Other Comprehensi30

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 26, 2015
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income (Loss)	Other comprehensive income (loss) includes certain changes in equity that are excluded from net income. The following table sets forth the changes in accumulated other comprehensive income by component for the nine months ended September 26, 2015 (in thousands): Unrealized Gain (Loss) on Other Available-for-Sale Securities Foreign Currency Translation Accumulated Tax Effect Total Balance at December 27, 2014 $ (444 ) $ (3,414 ) $ (760 ) $ (4,618 ) Net current-period other comprehensive income 279 4,699 — 4,978 Balance at September 26, 2015 $ (165 ) $ 1,285 $ (760 ) $ 360

Basic and Diluted Net Income 31

Basic and Diluted Net Income Per Common Share (Tables)	9 Months Ended
	Sep. 26, 2015
Earnings Per Share [Abstract]
Computation of Net Income (Loss) Per Common Share Basic and Diluted	The following table sets forth the computation of net income per common share – basic and diluted (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Numerator: Net income $ 8,510 $ 4,843 $ 38,782 $ 5,249 Denominator: Basic weighted average common shares outstanding 134,834 124,378 131,007 122,953 Effect of dilutive securities: Employee equity plans 5,397 4,586 5,911 4,109 Assumed conversion of convertible senior notes from conversion spread 5,069 — 4,164 — Diluted weighted average common shares outstanding 145,300 128,964 141,082 127,062 Net income per common share Basic $ 0.06 $ 0.04 $ 0.30 $ 0.04 Diluted $ 0.06 $ 0.04 $ 0.27 $ 0.04
Antidilutive Shares Excluded from Computation of Diluted Net Income (Loss) Per Share	The following sets forth the potentially dilutive shares excluded from the computation of the diluted net income per share because their effect was anti-dilutive (in thousands): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Stock options 1 447 7 706 RSUs 26 68 535 250 PSUs — 185 97 185 ESPP shares 484 801 300 921 Total 511 1,501 939 2,062

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	9 Months Ended
	Sep. 26, 2015
Debt Disclosure [Abstract]
Components of Convertible Senior Notes	The net carrying amounts of the debt obligation were as follows (in thousands): September 26, 2015 December 27, 2014 Principal $ 150,000 $ 150,000 Unamortized discount (1) (26,778 ) (33,106 ) Total long-term debt, net $ 123,222 $ 116,894 Unamortized issuance cost (1) (2,304 ) (2,848 ) Net carrying amount $ 120,918 $ 114,046 (1) Unamortized debt conversion discount and issuance costs will be amortized over the remaining life of the Notes, which is approximately three years.
Interest expense recognized related to Notes	The following table sets forth total interest expense recognized related to the Notes (in thousands): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Contractual interest expense $ 656 $ 656 $ 1,969 $ 1,969 Amortization of debt issuance costs 186 169 544 493 Amortization of debt discount 2,162 1,956 6,328 5,724 Total interest expense $ 3,004 $ 2,781 $ 8,841 $ 8,186

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 26, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	Future annual minimum operating lease payments at September 26, 2015 were as follows (in thousands): 2015 2016 2017 2018 2019 Thereafter Total Operating lease payments $ 2,492 $ 10,628 $ 10,277 $ 9,783 $ 8,871 $ 10,857 $ 52,908
Contractual Obligation, Fiscal Year Maturity Schedule	Future purchase commitments at September 26, 2015 were as follows (in thousands): 2015 2016 2017 2018 2019 Thereafter Total Purchase commitments $ 103,834 $ 3,750 $ — $ — $ — $ — $ 107,584

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 26, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Company's Equity Award Activity - Options	The following tables summarize the Company’s equity award activity and related information (in thousands, except per share data): Number of Stock Options Weighted-Average Exercise Price Per Share Aggregate Intrinsic Value Outstanding at December 27, 2014 4,298 $ 7.29 $ 32,833 Stock options granted — $ — Stock options exercised (1,518 ) $ 7.36 $ 18,013 Stock options canceled — $ — Outstanding at September 26, 2015 2,780 $ 7.25 $ 35,768 Vested and expected to vest as of September 26, 2015 2,779 $ 35,758 Exercisable at September 26, 2015 2,756 $ 7.24 $ 35,485
Summary of Company's Equity Award Activity - RSUs	Number of Restricted Stock Units Weighted- Average Grant Date Fair Value Per Share Aggregate Intrinsic Value Outstanding at December 27, 2014 6,042 $ 8.14 $ 90,085 RSUs granted 1,899 $ 18.41 RSUs released (2,883 ) $ 7.78 $ 50,734 RSUs canceled (227 ) $ 10.55 Outstanding at September 26, 2015 4,831 $ 12.28 $ 97,155 Expected to vest at September 26, 2015 4,608 $ 92,675
Summary of Company's Equity Award Activity - PSUs	Number of Performance Stock Units Weighted- Average Grant Date Fair Value Per Share Aggregate Intrinsic Value Outstanding at December 27, 2014 876 $ 7.49 $ 13,067 PSUs granted 309 $ 18.15 PSUs performance earned (1) 129 $ 7.32 PSUs released (413 ) $ 7.00 $ 7,231 PSUs canceled (193 ) $ 8.03 Outstanding at September 26, 2015 708 $ 12.12 $ 14,244 Expected to vest at September 26, 2015 686 $ 13,794 (1) Represents the additional PSUs awarded resulting from the achievement of performance goals above the performance targets established at grant.
Total Stock Based Compensation Cost for Instruments Granted but Not Yet Amortized	The following table presents total stock-based compensation cost for instruments granted but not yet amortized, net of estimated forfeitures, of the Company’s equity compensation plans as of September 26, 2015 . These costs are expected to be amortized on a straight-line basis over the following weighted-average periods (in thousands, except for weighted-average period): Unrecognized Compensation Expense, Net Weighted- Average Period (in years) Stock options $ 83 1.5 RSUs $ 42,314 2.4 PSUs $ 4,720 1.3
Ranges of Estimated Values of Stock Options and Performance-Based Stock Options Granted	The estimated values of stock options, as well as assumptions used in calculating these values were based on estimates as follows (expense amounts in thousands): Three Months Ended Nine Months Ended Employee and Director Stock Options September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Volatility N/A N/A N/A 52% Risk-free interest rate N/A N/A N/A 1.3% Expected life N/A N/A N/A 4.3 years Estimated fair value N/A N/A N/A $3.85 Total stock-based compensation expense $37 $108 $160 $623 _________________ N/A Not applicable because the Company did not grant any stock options during the period.
Estimated Fair Value of ESPP Shares	The fair value of the ESPP shares was estimated at the date of grant using the following assumptions (expense amounts in thousands): Three Months Ended Nine Months Ended Employee Stock Purchase Plan September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Volatility 39% 46% 39% - 53% 46% - 51% Risk-free interest rate 0.26% 0.06% 0.13% - 0.26% 0.02% - 0.11% Expected life 0.5 years 0.5 years 0.5 years 0.3 - 0.5 years Estimated fair value $6.43 $2.54 $5.15 - $6.43 $2.05 - $2.57 Total stock-based compensation expense $1,147 $1,092 $3,275 $2,726
Schedule of Share-based Payment Award, Valuation Assumptions	The ranges of estimated values of the PSUs granted that are compared to an index, as well as the assumptions used in calculating these values were based on estimates as follows: 2015 2014 2013 Index SPGIIPTR SPGIIPTR NASDAQ Telecom Composite Index volatility 18% - 19% 25% 23% Infinera volatility 48% 49% - 50% 55% Risk-free interest rate 0.97% - 1.10% 0.66% - 0.71% 0.42% Correlation with index 0.52 0.60 0.56 Estimated fair value $18.08 - $19.29 $6.59 - $7.60 $6.27 - $7.06
Schedule Of Nonvested Performance Based Units Activity By Grant Year	The following table summarizes by grant year, the Company’s PSU activity for the nine months ended September 26, 2015 (in thousands): Total Number of Performance Stock Units 2012 2013 2014 2015 Outstanding at December 27, 2014 876 191 296 389 — PSUs granted 309 — — — 309 PSUs performance earned (1) 129 — 74 55 — PSUs released (413 ) — (223 ) (184 ) (6 ) PSUs canceled (193 ) (191 ) — — (2 ) Outstanding at September 26, 2015 708 — 147 260 301 (1) Represents the additional PSUs awarded resulting from the achievement of performance goals above the performance targets established at grant.
Summary of Effects of Stock-Based Compensation on Company's Balance Sheets and Statements of Operations	The following tables summarize the effects of stock-based compensation on the Company’s condensed consolidated balance sheets and statements of operations for the periods presented (in thousands): September 26, 2015 December 27, 2014 Stock-based compensation effects in inventory $ 3,202 $ 3,088 Stock-based compensation effects in deferred inventory cost $ 13 $ 13 Stock-based compensation effects in fixed assets $ 100 $ 119 Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Stock-based compensation effects included in net income before income taxes Cost of revenue $ 645 $ 492 $ 1,740 $ 1,421 Research and development 2,788 2,270 8,183 6,488 Sales and marketing 2,131 1,982 5,922 5,517 General and administration 1,911 1,628 5,406 4,707 $ 7,475 $ 6,372 $ 21,251 $ 18,133 Cost of revenue – amortization from balance sheet (1) 976 999 2,617 2,714 Total stock-based compensation expense $ 8,451 $ 7,371 $ 23,868 $ 20,847 (1) Stock-based compensation expense deferred to inventory and deferred inventory costs in prior periods and recognized in the current period.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 26, 2015
Segment Reporting [Abstract]
Revenue and Long-Lived Assets by Geographic Region	Revenue by geographic region is based on the shipping address of the customer. The following tables set forth revenue and long-lived assets by geographic region (in thousands): Revenue Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Americas: United States $ 158,845 $ 120,769 $ 440,610 $ 367,802 Other Americas 20,874 9,230 39,944 17,526 179,719 129,999 480,554 385,328 Europe, Middle East and Africa 41,655 34,131 114,163 78,978 Asia Pacific and Japan 11,098 9,429 31,963 17,467 Total revenue $ 232,472 $ 173,559 $ 626,680 $ 481,773
Property, Plant and Equipment, Net	Property, plant and equipment, net September 26, 2015 December 27, 2014 United States $ 91,052 $ 79,025 Other Americas 135 196 Europe, Middle East and Africa 5,485 1,477 Asia Pacific and Japan 2,048 868 Total property, plant and equipment, net $ 98,720 $ 81,566

Guarantees (Tables)

Guarantees (Tables)	9 Months Ended
	Sep. 26, 2015
Guarantees [Abstract]
Activity Related to Product Warranty	Activity related to product warranty was as follows (in thousands): Three Months Ended Nine Months Ended September 26, 2015 September 27, 2014 September 26, 2015 September 27, 2014 Beginning balance $ 28,439 $ 27,948 $ 27,040 $ 22,908 Charges to operations 10,791 5,820 22,158 18,181 Utilization (3,515 ) (2,312 ) (8,336 ) (7,924 ) Change in estimate (1) 1,026 (3,650 ) (4,121 ) (5,359 ) Balance at the end of the period $ 36,741 $ 27,806 $ 36,741 $ 27,806 (1) The Company records hardware warranty liabilities based on the latest quality and cost information available as of that date. The changes in estimate shown here are due to changes in overall actual failure rates, the mix of new versus used units related to replacement of failed units, and changes in the estimated cost of repair. As the Company's products mature over time, failure rates and repair costs generally decline leading to favorable changes in warranty reserves.

Basis of Presentation and Sig37

Basis of Presentation and Significant Accounting Polices (Details)	3 Months Ended		9 Months Ended
	Sep. 26, 2015customer	Sep. 27, 2014customer	Sep. 26, 2015customer	Sep. 27, 2014customer	Aug. 20, 2015	May. 30, 2013USD ($)
Concentration Risk [Line Items]
Customers accounting for a significant portion of revenue | customer	2	1	2	1
Sales Revenue, Net | Customer One | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk	26.00%	25.00%	18.00%	20.00%
Sales Revenue, Net | Customer Two | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk	16.00%		15.00%
Transmode
Concentration Risk [Line Items]
Percentage of acquiree common shares acquired					95.80%
1.75% Convertible Senior Notes Due June 1, 2018
Concentration Risk [Line Items]
Principal amount						$ 150,000,000
Debt instrument interest percentage	1.75%	1.75%	1.75%	1.75%		1.75%

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Assets
Total Assets	$ 221,025	$ 325,705
Money market funds
Assets
Total Assets	29,694	21,478
Certificates of deposit
Assets
Total Assets	7,305	8,060
Commercial paper
Assets
Total Assets	13,662	46,072
Corporate bonds
Assets
Total Assets	170,335	235,285
U.S. treasuries
Assets
Total Assets	0	14,810
Foreign currency exchange forward contracts
Assets
Total Assets	29	0
Liabilities
Total Liabilities	(74)	(64)
Level 1
Assets
Total Assets	29,694	36,288
Level 1 | Money market funds
Assets
Total Assets	29,694	21,478
Level 1 | Certificates of deposit
Assets
Total Assets	0	0
Level 1 | Commercial paper
Assets
Total Assets	0	0
Level 1 | Corporate bonds
Assets
Total Assets	0	0
Level 1 | U.S. treasuries
Assets
Total Assets	0	14,810
Level 1 | Foreign currency exchange forward contracts
Assets
Total Assets	0	0
Liabilities
Total Liabilities	0	0
Level 2
Assets
Total Assets	191,331	289,417
Level 2 | Money market funds
Assets
Total Assets	0	0
Level 2 | Certificates of deposit
Assets
Total Assets	7,305	8,060
Level 2 | Commercial paper
Assets
Total Assets	13,662	46,072
Level 2 | Corporate bonds
Assets
Total Assets	170,335	235,285
Level 2 | U.S. treasuries
Assets
Total Assets	0	0
Level 2 | Foreign currency exchange forward contracts
Assets
Total Assets	29	0
Liabilities
Total Liabilities	(74)	(64)
Level 3
Assets
Total Assets	0	0
Level 3 | Money market funds
Assets
Total Assets	0	0
Level 3 | Certificates of deposit
Assets
Total Assets	0	0
Level 3 | Commercial paper
Assets
Total Assets	0	0
Level 3 | Corporate bonds
Assets
Total Assets	0	0
Level 3 | U.S. treasuries
Assets
Total Assets	0	0
Level 3 | Foreign currency exchange forward contracts
Assets
Total Assets	0	0
Liabilities
Total Liabilities	$ 0	$ 0

Fair Value Measurements - Inves

Fair Value Measurements - Investments at Fair Value (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	$ 221,161	$ 326,149
Gross Unrealized Gains	12	3
Gross Unrealized Losses	(177)	(447)
Fair Value	220,996	325,705
Money market funds
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	29,694	21,478
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	29,694	21,478
Certificates of deposit
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	7,300	8,060
Gross Unrealized Gains	5	0
Gross Unrealized Losses	0	0
Fair Value	7,305	8,060
Commercial paper
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	13,661	46,073
Gross Unrealized Gains	1	0
Gross Unrealized Losses	0	(1)
Fair Value	13,662	46,072
Corporate bonds
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	170,506	235,713
Gross Unrealized Gains	6	2
Gross Unrealized Losses	(177)	(430)
Fair Value	$ 170,335	235,285
U.S. treasuries
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost		14,825
Gross Unrealized Gains		1
Gross Unrealized Losses		(16)
Fair Value		$ 14,810

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 26, 2015	Dec. 27, 2014
Fair Value Disclosures [Abstract]
Available-for-sale investments	23 months
Cash	$ 117.7	$ 59.7

Cost-method Investment - Additi

Cost-method Investment - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 26, 2015	Dec. 27, 2014
Investments, All Other Investments [Abstract]
Cost-method investment	$ 14,500,000	$ 14,500,000
Less than percent of voting securities	20.00%
Impairment charge on cost-method investments	$ 0

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 26, 2015USD ($)	Sep. 27, 2014USD ($)	Sep. 26, 2015USD ($)	Sep. 27, 2014USD ($)	Jul. 31, 2015USD ($)	Jul. 31, 2015SEK	Apr. 30, 2015USD ($)	Apr. 30, 2015SEK
Derivative [Line Items]
Unrealized gain from forward contract	$ (3,200,000)		$ 1,600,000
British pound denominated receivables and typically maturities period	35 days		35 days
Euro denominated forward contracts maturity period	35 days		35 days
Before-tax effect of foreign currency exchange forward contracts not designated as hedging instruments, gain (loss)	$ (300,000)	$ 1,200,000	$ (3,100,000)	$ (800,000)
April 9, 2015 Foreign Currency Exchange Forward Contract
Derivative [Line Items]
Forward contract notional amount							$ 95,300,000	SEK 831,000,000
July 9, 2015 Purchase Foreign Currency Exchange Option Contracts
Derivative [Line Items]
Forward contract notional amount					$ 153,800,000	SEK 1,300,000,000
July 9, 2015 Sell Foreign Currency Exchange Option Contracts
Derivative [Line Items]
Forward contract notional amount					$ 76,900,000	SEK 650,000,000

Derivative Instruments - Fair V

Derivative Instruments - Fair Value of Derivative Instruments Not Designated as Hedging Activities (Details) - USD ($)		Sep. 26, 2015	Dec. 27, 2014
Derivative [Line Items]
Prepaid expenses and other current assets		$ 31,780,000	$ 24,636,000
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Forward contract notional amount	[1]	41,517,000	38,359,000
Prepaid expenses and other current assets		29,000
Prepaid Expense and Other Assets		(74,000)	(64,000)
Not Designated as Hedging Instrument [Member] | Euro Denominated Exchange Forward Contracts Receivables
Derivative [Line Items]
Forward contract notional amount	[1]	33,919,000	34,445,000
Prepaid expenses and other current assets		16,000
Prepaid Expense and Other Assets		(74,000)	(53,000)
Not Designated as Hedging Instrument [Member] | GBP Denominated Exchange Forward Contracts Receivables
Derivative [Line Items]
Forward contract notional amount		7,340,000	2,678,000	[1]
Prepaid expenses and other current assets		10,000
Prepaid Expense and Other Assets		0	(9,000)
Not Designated as Hedging Instrument [Member] | Foreign Currency Exchange Restricted Cash Forward Contracts
Derivative [Line Items]
Forward contract notional amount	[1]	258,000	1,236,000
Prepaid expenses and other current assets		3,000
Prepaid Expense and Other Assets		$ 0	$ (2,000)
[1]	Represents the face amounts of forward contracts that were outstanding as of the period noted.

Business Combination (Details)

Business Combination (Details) - USD ($) $ in Thousands	Aug. 20, 2015	Sep. 26, 2015	Sep. 26, 2015	Dec. 31, 2016	Dec. 27, 2014
Business Acquisition [Line Items]
Noncontrolling interest		$ 15,372	$ 15,372		$ 0
Transmode
Business Acquisition [Line Items]
Percentage of acquiree common shares acquired	95.80%
Noncontrolling interest	$ 15,372
Total consideration transfered	$ 350,640
Common shares issued in acquisition	7,873,055
Long-term deferred tax liabilities recorded in connection with the acquisition	$ 39,200
Operating Expense [Member] | Transmode
Business Acquisition [Line Items]
Expensed acquisition costs		$ 3,900	$ 6,700
Scenario, Forecast [Member] | Transmode
Business Acquisition [Line Items]
Percentage of acquiree common shares acquired				4.20%
Remaining acquiree shares (in shares)				1,200,000

Business Combination Total Cons

Business Combination Total Consideration For Acquisition (Details) - Transmode $ in Thousands	Aug. 20, 2015USD ($)
Business Acquisition [Line Items]
Cash	$ 181,133
Common stock (7,873,055 shares)	169,507
Total	$ 350,640

Business Combination Allocation

Business Combination Allocation Of Purchase Consideration (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Aug. 20, 2015	Dec. 27, 2014
Business Acquisition [Line Items]
Goodwill	$ 190,119		$ 0
Noncontrolling interest	$ (15,372)		$ 0
Transmode
Business Acquisition [Line Items]
Cash		$ 36,688
Accounts receivable		16,183
Inventory		19,886
Other assets		8,320
Intangible assets, net		161,845
Goodwill		187,220
Current liabilities		(24,320)
Long-term liabilities		(39,810)
Noncontrolling interest		(15,372)
Total net assets		$ 350,640

Business Combination Intangible

Business Combination Intangible Assets Acquired (Details) - USD ($) $ in Thousands	Aug. 20, 2015	Sep. 26, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets gross		$ 165,171
Transmode
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets gross	$ 161,845
Transmode | Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets acquired	$ 234
Intangible asset useful life	6 months
Transmode | Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets acquired	$ 49,033
Intangible asset useful life	8 years
Transmode | Developed Technology Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets acquired	$ 92,450
Intangible asset useful life	5 years
In-Process Technology [Member] | Transmode
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets acquired	$ 20,128

Business Combination Pro Forma

Business Combination Pro Forma (Details) - Transmode - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Business Acquisition [Line Items]
Revenue	$ 14,200
Net income	$ (4,000)
Revenue		$ 250,811	$ 201,406	$ 716,783	$ 582,978
Net income (loss)		$ 13,872	$ (1,200)	$ 44,633	$ (24,388)

Goodwill and Intangible Asset49

Goodwill and Intangible Assets Goodwill Roll Forward (Details) $ in Thousands	9 Months Ended
	Sep. 26, 2015USD ($)
Goodwill [Roll Forward]
Balance as of December 27, 2014	$ 0
Goodwill acquired	190,119
Accumulated impairment loss	0
Balance as of September 26, 2015	$ 190,119

Goodwill and Intangible Asset50

Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 26, 2015	Sep. 26, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 2.6	$ 2.6

Goodwill and Intangible Asset51

Goodwill and Intangible Assets - Purchased Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 144,731
Accumulated Amortization	(3,089)
Net Carrying Amount	141,642
Intangible assets gross	165,171
Intangible assets	162,082	$ 0
Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	238
Accumulated Amortization	(48)
Net Carrying Amount	190
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	49,793
Accumulated Amortization	(633)
Net Carrying Amount	49,160
Developed Technology Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	93,881
Accumulated Amortization	(1,909)
Net Carrying Amount	91,972
Other Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	819
Accumulated Amortization	(499)
Net Carrying Amount	320
In-Process Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 20,440

Goodwill and Intangible Asset52

Goodwill and Intangible Assets Future Amortization Expense (Details) $ in Thousands	Sep. 26, 2015USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2015	$ 6,428
2,016	25,302
2,017	25,233
2,018	25,233
2,019	25,233
2020 and Thereafter	$ 34,213

Balance Sheet Details Selected

Balance Sheet Details Selected Balance Sheet Items (Details) - USD ($) $ in Thousands		Sep. 26, 2015	Dec. 27, 2014
Inventory:
Raw materials		$ 24,234	$ 15,169
Work in process		48,464	50,046
Finished goods	[1]	97,177	81,285
Total inventory		169,875	146,500
Property, plant and equipment, net:
Property, plant and equipment, gross		275,642	242,364
Less accumulated depreciation and amortization		(176,922)	(160,798)
Total property, plant and equipment, net		98,720	81,566
Accrued expenses:
Loss contingency related to non-cancelable purchase commitments		6,437	5,390
Professional and other consulting fees		4,446	1,831
Taxes payable		3,085	3,993
Royalties		3,716	2,648
Accrued rebate and customer prepay liability		1,973	941
Accrued interest on convertible senior notes		901	219
Other accrued expenses		15,146	11,419
Total accrued expenses		35,704	26,441
Enterprise Resource Planning Systems
Property, plant and equipment, net:
Property, plant and equipment, gross		7,900	7,900
Total property, plant and equipment, net		4,300	5,200
Computer hardware
Property, plant and equipment, net:
Property, plant and equipment, gross		10,632	8,785
Computer software
Property, plant and equipment, net:
Property, plant and equipment, gross	[2]	20,200	17,684
Laboratory and manufacturing equipment
Property, plant and equipment, net:
Property, plant and equipment, gross		182,363	162,004
Furniture and fixtures
Property, plant and equipment, net:
Property, plant and equipment, gross		1,741	1,340
Leasehold improvements
Property, plant and equipment, net:
Property, plant and equipment, gross		38,505	37,825
Construction in progress
Property, plant and equipment, net:
Property, plant and equipment, gross		22,201	14,726
Customer Locations
Accrued expenses:
Inventory awaiting customer acceptance		$ 8,000	$ 10,200
[1]	Included in finished goods inventory at September 26, 2015 and December 27, 2014 were $8.0 million and $10.2 million, respectively, of inventory at customer locations for which product acceptance had not occurred.
[2]	Included in computer software at September 26, 2015 and December 27, 2014 were $7.9 million and $7.9 million, respectively, related to an enterprise resource planning ("ERP") system that the Company implemented during 2012. The unamortized ERP costs at September 26, 2015 and December 27, 2014 were $4.3 million and $5.2 million, respectively.

Balance Sheet Details - Restric

Balance Sheet Details - Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Value added tax license	$ 1,372	$ 1,309
Customer proposal guarantee	2,858	3,074
Property leases	699	699
Other restricted cash	390	378
Long-term restricted cash	$ 5,319	$ 5,460

Accumulated Other Comprehensi55

Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			$ (4,618)
Net current-period other comprehensive income	$ 4,819	$ (543)	4,978	$ (169)
Ending balance	360		360
Unrealized Gain (Loss) on Other Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(444)
Net current-period other comprehensive income			279
Ending balance	(165)		(165)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(3,414)
Net current-period other comprehensive income			4,699
Ending balance	1,285		1,285
Accumulated Tax Effect
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(760)
Net current-period other comprehensive income			0
Ending balance	$ (760)		$ (760)

Basic and Diluted Net Income 56

Basic and Diluted Net Income Per Common Share - Computation of Net Income Per Common Share Basic and Diluted (Details) - USD ($) $ / shares in Units, 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 income	$ 8,510	$ 4,843	$ 38,782	$ 5,249
Denominator:
Basic weighted average common shares outstanding (in shares)	134,834	124,378	131,007	122,953
Effect of dilutive securities:
Employee equity plans (in shares)	5,397	4,586	5,911	4,109
Assumed conversion of convertible senior notes from conversion spread (in shares)	5,069	0	4,164	0
Diluted weighted average common shares outstanding (in shares)	145,300	128,964	141,082	127,062
Net income per common share
Basic (in usd per share)	$ 0.06	$ 0.04	$ 0.30	$ 0.04
Diluted (in usd per share)	$ 0.06	$ 0.04	$ 0.27	$ 0.04

Basic and Diluted Net Income 57

Basic and Diluted Net Income Per Common Share - Antidilutive Shares Excluded from Computation of Diluted Income Loss Per Share (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]
Antidilutive securities excluded from earnings per share computation (in shares)	511	1,501	939	2,062
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share computation (in shares)	1	447	7	706
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share computation (in shares)	26	68	535	250
PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share computation (in shares)	0	185	97	185
ESPP shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share computation (in shares)	484	801	300	921

Basic and Diluted Net Income 58

Basic and Diluted Net Income Per Common Share - Additional Information (Details) - 1.75% Convertible Senior Notes Due June 1, 2018 - USD ($)	Sep. 26, 2015	Sep. 27, 2014	May. 30, 2013
Principal amount			$ 150,000,000
Debt instrument interest percentage	1.75%	1.75%	1.75%

Convertible Senior Notes - Addi

Convertible Senior Notes - Additional Information (Details)	1 Months Ended	3 Months Ended	9 Months Ended
	May. 31, 2013USD ($)d	Sep. 26, 2015USD ($)d$ / shares	Sep. 26, 2015USD ($)$ / shares	Jun. 26, 2015$ / shares	Dec. 27, 2014USD ($)	Sep. 27, 2014	May. 30, 2013USD ($)$ / shares
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase price as a percentage on principal amount of the notes upon the occurrence of a fundamental change	100.00%
Remaining life of note			3 years
Deferred tax liability, non-current		$ 39,374,000	$ 39,374,000		$ 2,132,000
Total estimated fair value of the notes		$ 250,500,000	$ 250,500,000
Closing price of common stock (in usd per share) | $ / shares		$ 20.11	$ 20.11	$ 20.11
1.75% Convertible Senior Notes Due June 1, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal amount							$ 150,000,000
Debt instrument interest percentage		1.75%	1.75%			1.75%	1.75%
Proceeds from issuance of debt, net			$ 144,500,000
Initial conversion rate per $1,000 principal amount of Notes	0.0794834
Initial conversion price (in usd per share) | $ / shares							$ 12.58
Debt instrument, convertible, if-converted value in excess of principal		$ 89,800,000
Initial transaction amount and net carrying amount, APIC		43,300,000	43,300,000		43,300,000
Debt issuance cost			5,500,000
Deferred tax liability, non-current		$ 17,000,000	$ 17,000,000
Additional effective rate of interest to be used on amortized carrying value		10.23%	10.23%			10.23%
Convertible Senior Notes, Conversion Circumstance One
Accounts, Notes, Loans and Financing Receivable [Line Items]
Convertible threshold consecutive trading days	30 days	30 days
Convertible threshold minimum percentage	130.00%	130.00%
Threshold trading days for debt instrument conversion | d	20	20
Convertible Senior Notes, Conversion Circumstance Two
Accounts, Notes, Loans and Financing Receivable [Line Items]
Convertible threshold consecutive trading days	5 days
Convertible threshold business days | d	5
Debt instrument, convertible, if-converted value in excess of principal	$ 1,000
Convertible, threshold maximum percentage	98.00%
Additional Paid-in Capital | 1.75% Convertible Senior Notes Due June 1, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt Instrument, Convertible, Carrying Amount of Equity Component		$ 45,000,000	$ 45,000,000		45,000,000
Debt issuance costs attributable to the equity component		$ 1,700,000	$ 1,700,000		$ 1,700,000

Convertible Senior Notes - Comp

Convertible Senior Notes - Components of Convertible Senior Notes (Details) - USD ($)		Sep. 26, 2015	Dec. 27, 2014	May. 30, 2013
Debt Instrument [Line Items]
Unamortized discount	[1]	$ (26,778,000)	$ (33,106,000)
Long-term debt, net		123,222,000	116,894,000
Unamortized issuance cost	[1]	(2,304,000)	(2,848,000)
1.75% Convertible Senior Notes Due June 1, 2018
Debt Instrument [Line Items]
Principal amount				$ 150,000,000
Net carrying amount		120,918,000	114,046,000
1.75% Convertible Senior Notes Due June 1, 2018 | Long-term Debt
Debt Instrument [Line Items]
Principal amount		$ 150,000,000	$ 150,000,000
[1]	Unamortized debt conversion discount and issuance costs will be amortized over the remaining life of the Notes, which is approximately three years.

Convertible Senior Notes - Inte

Convertible Senior Notes - Interest Expense Recognized Related to Notes Prior to Capitalization of Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Debt Disclosure [Abstract]
Contractual interest expense	$ 656	$ 656	$ 1,969	$ 1,969
Amortization of debt issuance costs	186	169	544	493
Amortization of debt discount	2,162	1,956	6,328	5,724
Total interest expense	$ 3,004	$ 2,781	$ 8,841	$ 8,186

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (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
Registration Payment Arrangement [Line Items]
Operating lease renewal period			5 years
Asset retirement obligation	$ 2,800		$ 2,800		$ 2,700
Rent expense incurred	2,300	$ 1,800	6,000	$ 5,400
Purchase obligation	107,584		107,584		$ 128,300
Uncertain tax positions	$ 2,600		$ 2,600
Minimum
Registration Payment Arrangement [Line Items]
Operating lease period			1 year
Maximum
Registration Payment Arrangement [Line Items]
Operating lease period			10 years

Commitments and Contingencies63

Commitments and Contingencies - Future Annual Minimum Operating Lease Payments (Details) $ in Thousands	Sep. 26, 2015USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,015	$ 2,492
2,016	10,628
2,017	10,277
2,018	9,783
2,019	8,871
Thereafter	10,857
Total	$ 52,908

Commitments and Contingencies64

Commitments and Contingencies - Future Purchase Commitments (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Commitments and Contingencies Disclosure [Abstract]
2,015	$ 103,834
2,016	3,750
2,017	0
2,018	0
2,019	0
Thereafter	0
Total	$ 107,584	$ 128,300

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 26, 2015USD ($)$ / sharesshares	Sep. 27, 2014USD ($)	Sep. 26, 2015USD ($)$ / sharesshares	Sep. 27, 2014USD ($)	Jun. 26, 2015$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted options to employees to purchase shares of common stock (in shares)	15,600		15,600
Closing price of common stock (in usd per share) | $ / shares	$ 20.11		$ 20.11		$ 20.11
Performance Stock Unit Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amortization of stock-based compensation | $	$ 1.6	$ 0.6	$ 3.8	$ 1.5
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant cost (in shares)			309
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant cost (in shares)	200		1,899
Amortization of stock-based compensation | $	$ 5.6	$ 5.6	$ 16.7	$ 15.9
Two Thousand And Seven Equity Incentive Plan | PSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ranges of number of shares issued on vesting of PSUs			0
Two Thousand And Seven Equity Incentive Plan | PSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ranges of number of shares issued on vesting of PSUs			1.5
Existing Employees | Vesting 1 | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of grants based on shareholder return of common stock price versus designated index			1 year
Existing Employees | Vesting 2 | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of grants based on shareholder return of common stock price versus designated index			2 years
Existing Employees | Vesting 3 | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of grants based on shareholder return of common stock price versus designated index			3 years

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Company's Equity Award Activity - Options (Details) - Stock options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 26, 2015
Number of Stock Options
Number of Options, beginning balance (in shares)	4,298
Number of Options, granted (in shares)	0
Number of Options, exercised (in shares)	(1,518)
Number of Options, canceled (in shares)	0
Number of Options, ending balance (in shares)	2,780
Number of Options, vested and expected to vest (in shares)	2,779
Number of Options, exercisable (in shares)	2,756
Weighted-Average Exercise Price Per Share
Weighted-Average Exercise Price Per Share, beginning balance (in usd per share)	$ 7.29
Weighted-Average Exercise Per Share, Options granted (in usd per share)	0
Weighted-Average Exercise Price Per Share, Options exercised (in usd per share)	7.36
Weighted-Average Exercise Price Per Share, Options canceled (in usd per share)	0
Weighted-Average Exercise Price Per Share, ending balance (in usd per share)	7.25
Average Exercise Price Per Share, Exercisable (in usd per share)	$ 7.24
Aggregate Intrinsic Value
Aggregate Intrinsic Value, beginning balance	$ 32,833
Aggregate Intrinsic Value, Options exercised	18,013
Aggregate Intrinsic Value, ending balance	35,768
Aggregate Intrinsic Value, Vested and expected to vest	35,758
Aggregate Intrinsic Value, Exercisable	$ 35,485

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Company's Equity Award Activity - RSUs (Details) - Restricted Stock Units $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 26, 2015USD ($)$ / sharesshares	Sep. 26, 2015USD ($)$ / sharesshares
Number of Restricted Stock Units
Number of Restricted/Performance Stock Units, beginning balance (in shares)		6,042
Number of shares available for grant cost (in shares)	200	1,899
Number of Restricted/Performance Stock Units, released (in shares)		(2,883)
Number of Restricted Stock Units, canceled (in shares)		(227)
Number of Restricted/Performance Stock Units, ending balance (in shares)	4,831	4,831
Number of Restricted Stock Units, Expected to vest (in shares)	4,608	4,608
Weighted- Average Grant Date Fair Value Per Share
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in usd per share) | $ / shares		$ 8.14
Weighted-average fair value, granted (in usd per share) | $ / shares		18.41
Weighted-Average Grant Date Fair Value Per Share, released (in usd per share) | $ / shares		7.78
Weighted-Average Grant Date Fair Value Per Share, canceled (in usd per share) | $ / shares		10.55
Weighted-Average Grant Date Fair Value Per Share, ending balance (in usd per share) | $ / shares	$ 12.28	$ 12.28
Aggregate Intrinsic Value
Aggregate Intrinsic Value, beginning balance | $		$ 90,085
Aggregate Intrinsic Value, RSUs released | $		50,734
Aggregate Intrinsic Value, ending balance | $	$ 97,155	97,155
Aggregate Intrinsic Value, Expected to vest | $	$ 92,675	$ 92,675

Stockholders' Equity - Summar68

Stockholders' Equity - Summary of Company's Equity Award Activity - PSUs (Details) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 26, 2015USD ($)$ / sharesshares	Sep. 27, 2014USD ($)	Sep. 26, 2015USD ($)$ / sharesshares	Sep. 27, 2014USD ($)	Dec. 27, 2014USD ($)$ / sharesshares	Dec. 28, 2013$ / shares	Jun. 26, 2015$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing price of common stock (in usd per share) | $ / shares		$ 20.11		$ 20.11				$ 20.11
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
NASDAQ Telecom Composite Index Volatility							23.00%
SPGIIPTR Index Volatility						25.00%
Risk-free interest rate							0.42%
Volatility				48.00%			55.00%
Number of Performance Stock Units
Number of Restricted/Performance Stock Units, beginning balance (in shares)				876
Number of shares available for grant cost (in shares)				309
Number of Restricted/Performance Stock Units, released (in shares)				(413)
Number of Restricted Stock Units, canceled (in shares)				(193)
Number of Restricted/Performance Stock Units, ending balance (in shares)		708		708		876
Number of Restricted Stock Units, Expected to vest (in shares)		686		686
Weighted- Average Grant Date Fair Value Per Share
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in usd per share) | $ / shares				$ 7.49
Weighted-average fair value, granted (in usd per share) | $ / shares				18.15
Weighted-Average Grant Date Fair Value Per Share, released (in usd per share) | $ / shares				7
Weighted-Average Grant Date Fair Value Per Share, canceled (in usd per share) | $ / shares				8.03
Weighted-Average Grant Date Fair Value Per Share, ending balance (in usd per share) | $ / shares		$ 12.12		$ 12.12		$ 7.49
Aggregate Intrinsic Value
Aggregate Intrinsic Value, beginning balance | $				$ 13,067
Aggregate Intrinsic Value, PSUs released | $				7,231
Aggregate Intrinsic Value, ending balance | $		$ 14,244		14,244		$ 13,067
Aggregate Intrinsic Value, Expected to vest | $		13,794		$ 13,794
Additional Grants For Performance
Number of Performance Stock Units
Number of shares available for grant cost (in shares)	[1],[2]			129
Weighted- Average Grant Date Fair Value Per Share
Weighted-average fair value, granted (in usd per share) | $ / shares	[2]			$ 7.32
Performance Stock Unit Grants
Number of Performance Stock Units
Amortization of stock-based compensation | $		$ 1,600	$ 600	$ 3,800	$ 1,500
Minimum | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
SPGIIPTR Index Volatility				18.00%
Risk-free interest rate				0.97%		0.66%
Volatility						49.00%
Weighted- Average Grant Date Fair Value Per Share
Weighted-average fair value, granted (in usd per share) | $ / shares				$ 18.08		$ 6.59	$ 6.27
Maximum | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
SPGIIPTR Index Volatility				19.00%
Risk-free interest rate				1.10%		0.71%
Volatility						50.00%
Weighted- Average Grant Date Fair Value Per Share
Weighted-average fair value, granted (in usd per share) | $ / shares				$ 19.29		$ 7.60	$ 7.06
Fiscal Year 2012 Grant | PSUs
Number of Performance Stock Units
Number of Restricted/Performance Stock Units, beginning balance (in shares)				191
Number of shares available for grant cost (in shares)				0
Number of Restricted/Performance Stock Units, released (in shares)				0
Number of Restricted Stock Units, canceled (in shares)				(191)
Number of Restricted/Performance Stock Units, ending balance (in shares)		0		0		191
Fiscal Year 2012 Grant | Additional Grants For Performance
Number of Performance Stock Units
Number of shares available for grant cost (in shares)	[1]			0
Fiscal Year 2014 Grant | PSUs
Number of Performance Stock Units
Number of Restricted/Performance Stock Units, beginning balance (in shares)				389
Number of shares available for grant cost (in shares)				0
Number of Restricted/Performance Stock Units, released (in shares)				(184)
Number of Restricted Stock Units, canceled (in shares)				0
Number of Restricted/Performance Stock Units, ending balance (in shares)		260		260		389
Fiscal Year 2014 Grant | Additional Grants For Performance
Number of Performance Stock Units
Number of shares available for grant cost (in shares)	[1]			55
Fiscal Year 2013 Grant | PSUs
Number of Performance Stock Units
Number of Restricted/Performance Stock Units, beginning balance (in shares)				296
Number of shares available for grant cost (in shares)				0
Number of Restricted/Performance Stock Units, released (in shares)				(223)
Number of Restricted Stock Units, canceled (in shares)				0
Number of Restricted/Performance Stock Units, ending balance (in shares)		147		147		296
Fiscal Year 2013 Grant | Additional Grants For Performance
Number of Performance Stock Units
Number of shares available for grant cost (in shares)	[1]			74
Fiscal Year 2015 Grant | PSUs
Number of Performance Stock Units
Number of Restricted/Performance Stock Units, beginning balance (in shares)				0
Number of shares available for grant cost (in shares)				309
Number of Restricted/Performance Stock Units, released (in shares)				(6)
Number of Restricted Stock Units, canceled (in shares)				(2)
Number of Restricted/Performance Stock Units, ending balance (in shares)		301		301		0
Fiscal Year 2015 Grant | Additional Grants For Performance
Number of Performance Stock Units
Number of shares available for grant cost (in shares)	[1]			0
Two Thousand And Seven Equity Incentive Plan | Minimum | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ranges of number of shares issued on vesting of PSUs				0
Two Thousand And Seven Equity Incentive Plan | Maximum | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ranges of number of shares issued on vesting of PSUs				1.5
[1]	Represents the additional PSUs awarded resulting from the achievement of performance goals above the performance targets established at grant.
[2]	Represents the additional PSUs awarded resulting from the achievement of performance goals above the performance targets established at grant.

Stockholders' Equity - Total St

Stockholders' Equity - Total Stock Based Compensation Cost for Instruments Granted but Not Yet Amortized (Details) shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 26, 2015USD ($)shares	Sep. 26, 2015USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, Unrecognized Compensation Expense, Net	$ 83	$ 83
Stock options, Weighted-Average Period (in years)		1 year 6 months 15 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense, Net	$ 42,314	$ 42,314
Weighted-Average Period (in years)		2 years 5 months 1 day
Number of shares available for grant cost (in shares) | shares	200	1,899
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense, Net	$ 4,720	$ 4,720
Weighted-Average Period (in years)		1 year 3 months
Number of shares available for grant cost (in shares) | shares		309

Stockholders' Equity - Ranges o

Stockholders' Equity - Ranges of Estimated Values of Stock Options and Performance-Based Stock Options Granted (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 26, 2015USD ($)$ / shares	Sep. 27, 2014USD ($)$ / shares	Sep. 26, 2015USD ($)$ / shares	Sep. 27, 2014USD ($)$ / shares	Dec. 27, 2014$ / shares	Dec. 28, 2013$ / shares	Jun. 26, 2015$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing price of common stock (in usd per share)	$ 20.11		$ 20.11				$ 20.11
Stock-based compensation expense | $	$ 8,451	$ 7,371	$ 23,868	$ 20,847
Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense | $	$ 37	$ 108	$ 160
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility				52.00%
Estimated fair value (in usd per share)				$ 3.85
Risk-free interest rate				1.30%
Expected life				4 years 4 months 2 days
Stock-based compensation expense | $				$ 623
Employee Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	39.00%	46.00%
Estimated fair value (in usd per share)	$ 6.43	$ 2.54
Risk-free interest rate	0.26%	0.06%
Expected life	6 months	6 months	6 months
Stock-based compensation expense | $	$ 1,147	$ 1,092	$ 3,275	$ 2,726
Employee Stock Purchase Plans | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility				49.00%
Estimated fair value (in usd per share)				$ 2.05
Risk-free interest rate				0.02%
Expected life				3 months 18 days
Employee Stock Purchase Plans | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility				51.00%
Estimated fair value (in usd per share)				$ 2.57
Risk-free interest rate				0.11%
Expected life				6 months
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value, granted (in usd per share)			$ 18.15
SPGIIPTR Index Volatility					25.00%
NASDAQ Telecom Composite Index Volatility						23.00%
Volatility			48.00%			55.00%
Risk-free interest rate						0.42%
Correlation with SPGIIPTR Index			0.52		0.60
Correlation with NASDAQ Telecom Composite Index						0.56
PSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value, granted (in usd per share)			$ 18.08		$ 6.59	$ 6.27
SPGIIPTR Index Volatility			18.00%
Volatility					49.00%
Risk-free interest rate			0.97%		0.66%
PSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value, granted (in usd per share)			$ 19.29		$ 7.60	$ 7.06
SPGIIPTR Index Volatility			19.00%
Volatility					50.00%
Risk-free interest rate			1.10%		0.71%

Stockholders' Equity - Estimate

Stockholders' Equity - Estimated Fair Value of ESPP Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 27, 2014	Dec. 28, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 8,451	$ 7,371	$ 23,868	$ 20,847
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility				52.00%
Risk-free interest rate				1.30%
Expected life				4 years 4 months 2 days
Estimated fair value (in usd per share)				$ 3.85
Stock-based compensation expense				$ 623
Employee Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	39.00%	46.00%
Risk-free interest rate	0.26%	0.06%
Expected life	6 months	6 months	6 months
Estimated fair value (in usd per share)	$ 6.43	$ 2.54
Stock-based compensation expense	$ 1,147	$ 1,092	$ 3,275	$ 2,726
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility			48.00%			55.00%
Risk-free interest rate						0.42%
Minimum | Employee Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility				49.00%
Risk-free interest rate				0.02%
Expected life				3 months 18 days
Estimated fair value (in usd per share)				$ 2.05
Minimum | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility					49.00%
Risk-free interest rate			0.97%		0.66%
Maximum | Employee Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility				51.00%
Risk-free interest rate				0.11%
Expected life				6 months
Estimated fair value (in usd per share)				$ 2.57
Maximum | PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility					50.00%
Risk-free interest rate			1.10%		0.71%

Stockholders' Equity - Summar72

Stockholders' Equity - Summary of Effects of Stock-Based Compensation on Company's Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Stock-Based Compensation Effects in Inventory
Effects Of Stock Based Compensation [Line Items]
Effects Of Stock Based Compensation	$ 3,202	$ 3,088
Stock-Based Compensation Effects in Deferred Inventory Cost
Effects Of Stock Based Compensation [Line Items]
Effects Of Stock Based Compensation	13	13
Stock-Based Compensation Effects in Fixed Assets
Effects Of Stock Based Compensation [Line Items]
Effects Of Stock Based Compensation	$ 100	$ 119

Stockholders' Equity - Summar73

Stockholders' Equity - Summary of Effects of Stock-Based Compensation on Company's Statements of Operations (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Effects Of Stock Based Compensation [Line Items]
Stock-based compensation effects included in net income before income taxes		$ 7,475	$ 6,372	$ 21,251	$ 18,133
Cost of revenue - amortization from balance sheet	[1]	976	999	2,617	2,714
Stock-based compensation expense		8,451	7,371	23,868	20,847
Cost of revenue
Effects Of Stock Based Compensation [Line Items]
Stock-based compensation effects included in net income before income taxes		645	492	1,740	1,421
Research and development
Effects Of Stock Based Compensation [Line Items]
Stock-based compensation effects included in net income before income taxes		2,788	2,270	8,183	6,488
Sales and marketing
Effects Of Stock Based Compensation [Line Items]
Stock-based compensation effects included in net income before income taxes		2,131	1,982	5,922	5,517
General and administration
Effects Of Stock Based Compensation [Line Items]
Stock-based compensation effects included in net income before income taxes		$ 1,911	$ 1,628	$ 5,406	$ 4,707
[1]	Stock-based compensation expense deferred to inventory and deferred inventory costs in prior periods and recognized in the current period.

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Business Acquisition [Line Items]
Provision for (benefit from) income taxes		$ (151)	$ 205	$ 1,473	$ 1,070
Pre-tax income (loss)		$ 8,359	$ 5,048	$ 40,255	$ 6,319
Transmode
Business Acquisition [Line Items]
Provision for (benefit from) income taxes	$ (1,400)
Purchase accounting amortization expense	$ 6,400

Segment Information - Revenue

Segment Information - Revenue and Long-Lived Assets by Geographic Region (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2015USD ($)	Sep. 27, 2014USD ($)	Sep. 26, 2015USD ($)segment	Sep. 27, 2014USD ($)
Segment Reporting [Abstract]
Number of reporting segments | segment			1
Number of operating segments | segment			1
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 232,472	$ 173,559	$ 626,680	$ 481,773
Operating Segments | United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	158,845	120,769	440,610	367,802
Operating Segments | Other Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	20,874	9,230	39,944	17,526
Operating Segments | Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	179,719	129,999	480,554	385,328
Operating Segments | Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	41,655	34,131	114,163	78,978
Operating Segments | Asia Pacific and Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 11,098	$ 9,429	$ 31,963	$ 17,467

Segment Information - Property,

Segment Information - Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 26, 2015	Dec. 27, 2014
Geographic Information For Property Plant And Equipment [Line Items]
Total property, plant and equipment, net	$ 98,720	$ 81,566
Operating Segments | United States
Geographic Information For Property Plant And Equipment [Line Items]
Total property, plant and equipment, net	91,052	79,025
Operating Segments | Other Americas
Geographic Information For Property Plant And Equipment [Line Items]
Total property, plant and equipment, net	135	196
Operating Segments | Europe, Middle East and Africa
Geographic Information For Property Plant And Equipment [Line Items]
Total property, plant and equipment, net	5,485	1,477
Operating Segments | Asia Pacific and Japan
Geographic Information For Property Plant And Equipment [Line Items]
Total property, plant and equipment, net	$ 2,048	$ 868

Guarantees - Additional Informa

Guarantees - Additional Information (Details)	9 Months Ended
	Sep. 26, 2015
Guarantor Obligations [Line Items]
Software Warranty Period	90 days
Minimum
Guarantor Obligations [Line Items]
Product Warranty Period	1 year
Maximum
Guarantor Obligations [Line Items]
Product Warranty Period	5 years

Guarantees - Activity Related t

Guarantees - Activity Related to Product Warranty (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Movement in Standard Product Warranty Accrual [Roll Forward]
Beginning balance		$ 28,439	$ 27,948	$ 27,040	$ 22,908
Charges to operations		10,791	5,820	22,158	18,181
Utilization		(3,515)	(2,312)	(8,336)	(7,924)
Change in estimate	[1]	1,026	(3,650)	(4,121)	(5,359)
Balance at the end of the period		$ 36,741	$ 27,806	$ 36,741	$ 27,806
[1]	The Company records hardware warranty liabilities based on the latest quality and cost information available as of that date. The changes in estimate shown here are due to changes in overall actual failure rates, the mix of new versus used units related to replacement of failed units, and changes in the estimated cost of repair. As the Company's products mature over time, failure rates and repair costs generally decline leading to favorable changes in warranty reserves.