MACOM Technology Solutions (MTSI) 10-K 15 Nov 18 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Sep. 28, 2018	Nov. 09, 2018	Mar. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 28, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Registrant Name	MACOM Technology Solutions Holdings, Inc.
Entity Central Index Key	1,493,594
Current Fiscal Year End Date	--09-28
Entity Well-known Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Share Outstanding		65,192,357
Entity Public Float			$ 0.7

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Current assets:
Cash and cash equivalents	$ 94,676	$ 130,104
Short-term investments	98,221	84,121
Accounts receivable (less allowances of $6,795 and $9,410, respectively)	97,375	136,096
Inventories	122,837	136,074
Income tax receivable	17,601	18,493
Assets held for sale	4,840	35,571
Prepaid and other current assets	23,311	22,438
Total current assets	458,861	562,897
Property, plant and equipment, net	149,923	131,019
Goodwill	314,076	313,765
Intangible assets, net	512,785	621,092
Deferred income taxes	2,272	948
Other investments	31,094	0
Other long-term assets	13,484	7,402
Total assets	1,482,495	1,637,123
Current liabilities:
Current portion of lease payable	467	815
Current portion long-term debt	6,885	6,885
Accounts payable	41,951	47,038
Accrued liabilities	49,945	58,243
Liabilities held for sale	0	2,144
Deferred revenue	7,757	1,994
Total current liabilities	107,005	117,119
Lease payable, less current portion	29,023	17,275
Long-term debt, less current portion	658,372	661,471
Warrant liability	13,129	40,775
Other long-term liabilities	5,902	7,937
Deferred income taxes	389	15,172
Total liabilities	813,820	859,749
Stockholders' equity:
Preferred stock, $0.001 par value, 10,000 shares authorized, no shares issued	0	0
Common stock, $0.001 par value, 300,000 shares authorized; 65,202 and 64,279 shares issued and 65,179 and 64,256 shares outstanding as of September 28, 2018 and September 29, 2017, respectively, of which 6 and 0 shares, respectively, are subject to forfeiture	65	64
Treasury Stock, at cost, 23 shares as of both September 28, 2018 and September 29, 2017	(330)	(330)
Accumulated other comprehensive income	2,188	2,977
Additional paid-in capital	1,074,728	1,041,644
Accumulated deficit	(407,976)	(266,981)
Total stockholders' equity	668,675	777,374
Total liabilities and stockholders' equity	$ 1,482,495	$ 1,637,123

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Statement of Financial Position [Abstract]
Allowances for accounts receivable	$ 6,795	$ 9,410
Preferred stock, par value (in USD per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	300,000,000	300,000,000
Common stock, issued (in shares)	65,202,000	64,279,000
Common stock, outstanding (in shares)	65,179,000	64,256,000
Common stock, subject to forfeiture (in shares)	6,100	200
Treasury stock (in shares)	23,000	23,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenue	$ 570,398	$ 698,772	$ 544,338
Cost of revenue	324,692	371,888	262,729
Gross profit	245,706	326,884	281,609
Operating expenses:
Research and development	177,713	147,986	107,698
Selling, general and administrative	161,673	187,886	145,433
Impairment charges	6,575	4,352	11,765
Restructuring charges	6,265	2,744	3,465
Total operating expenses	352,226	342,968	268,361
(Loss) income from operations	(106,520)	(16,084)	13,248
Other (expense) income:
Warrant liability gain (expense)	27,646	(2,522)	(16,431)
Interest expense, net	(31,338)	(28,855)	(18,427)
Other (expense) income	(45,023)	(2,044)	39
Total other expense, net	(48,715)	(33,421)	(34,819)
Loss before income taxes	(155,235)	(49,505)	(21,571)
Income tax (benefit) expense	(21,473)	100,911	(17,983)
Loss from continuing operations	(133,762)	(150,416)	(3,588)
(Loss) income from discontinued operations	(6,215)	(19,077)	5,022
Net (loss) income	$ (139,977)	$ (169,493)	$ 1,434
Basic (loss) income per share:
Income (loss) from continuing operations (in USD per share)	$ (2.07)	$ (2.48)	$ (0.07)
Income (loss) from discontinued operations (in USD per share)	(0.10)	(0.31)	0.09
(Loss) income per share-basic (in USD per share)	(2.16)	(2.79)	0.03
Diluted (loss) income per share:
Income (loss) from continuing operations (in USD per share)	(2.47)	(2.48)	(0.07)
(Loss) income from discontinued operations (in USD per share)	(0.10)	(0.31)	0.09
(Loss) income per share-diluted (in USD per share)	$ (2.57)	$ (2.79)	$ 0.03
Shares used:
Basic (in shares)	64,741	60,704	53,364
Diluted (in shares)	65,311	60,704	53,364

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (139,977)	$ (169,493)	$ 1,434
Unrealized loss on short-term investments, net of tax	(287)	(63)	(2)
Foreign currency translation (loss) gain, net of tax	(502)	(5,999)	11,320
Other comprehensive (loss) income, net of tax	(789)	(6,062)	11,318
Total comprehensive (loss) income	$ (140,766)	$ (175,555)	$ 12,752

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Additional Paid-In Capital	Accumulated Deficit
Beginning balance at Oct. 02, 2015	$ 424,533	$ 53	$ (330)	$ (2,279)	$ 526,011	$ (98,922)
Balance (in shares) at Oct. 02, 2015		52,958
Treasury stock (in shares) at Oct. 02, 2015			(23)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	1,253				1,253
Stock option exercise (in shares)		130
Vesting of restricted common stock and units	1	$ 1
Vesting of restricted common stock and units (in shares)		750
Issuance of common stock pursuant to employee stock purchase plan	4,207				4,207
Issuance of common stock pursuant to employee stock purchase plan (in shares)		154
Shares repurchased for tax withholdings on restricted stock awards	(9,995)	$ 0			(9,995)
Shares repurchased for tax withholdings on restricted stock awards (in shares)		(283)
Share-based compensation	26,954				26,954
Excess tax benefits	3,079				3,079
Other comprehensive income, net of tax	11,318			11,318
Net (loss) income	1,434					1,434
Ending balance at Sep. 30, 2016	462,784	$ 54	$ (330)	9,039	551,509	(97,488)
Balance (in shares) at Sep. 30, 2016		53,709
Treasury stock (in shares) at Sep. 30, 2016			(23)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	3,117				3,117
Stock option exercise (in shares)		234
Vesting of restricted common stock and units	0	$ 0
Vesting of restricted common stock and units (in shares)		984
Issuance of common stock pursuant to employee stock purchase plan	5,164				5,164
Issuance of common stock pursuant to employee stock purchase plan (in shares)		145
Shares repurchased for tax withholdings on restricted stock awards	(18,534)				(18,534)
Shares repurchased for tax withholdings on restricted stock awards (in shares)		(382)
Share-based compensation	36,335				36,335
Stock Issued During Period, Value, Acquisitions	465,082	$ 10			465,072
Equity issuance costs	(1,019)				(1,019)
Stock Issued During Period, Shares, Acquisitions		9,589
Other comprehensive income, net of tax	(6,062)			(6,062)
Net (loss) income	(169,493)					(169,493)
Ending balance at Sep. 29, 2017	$ 777,374	$ 64	$ (330)	2,977	1,041,644	(266,981)
Balance (in shares) at Sep. 29, 2017		64,279
Treasury stock (in shares) at Sep. 29, 2017	23		(23)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	$ 76	$ 0			76
Stock option exercise (in shares)	27	27
Vesting of restricted common stock and units	$ 1	$ 1
Vesting of restricted common stock and units (in shares)		906
Issuance of common stock pursuant to employee stock purchase plan	6,881				6,881
Issuance of common stock pursuant to employee stock purchase plan (in shares)		306
Shares repurchased for tax withholdings on restricted stock awards	(6,828)	$ 0			(6,828)
Shares repurchased for tax withholdings on restricted stock awards (in shares)		(316)
Share-based compensation	31,937				31,937
Other comprehensive income, net of tax	(789)			(789)
Net (loss) income	(139,977)					(139,977)
Ending balance at Sep. 28, 2018	$ 668,675	$ 65	$ (330)	$ 2,188	1,074,728	(407,976)
Balance (in shares) at Sep. 28, 2018		65,202
Treasury stock (in shares) at Sep. 28, 2018	23		(23)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 0				$ 1,018	$ (1,018)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net (loss) income	$ (139,977)	$ (169,493)	$ 1,434
Adjustments to reconcile net (loss) income to net cash from operating activities:
Depreciation and intangible amortization	112,383	92,998	70,591
Share-based compensation	31,937	36,335	26,954
Warrant liability (gain) expense	(27,646)	2,522	16,431
Acquired inventory step-up amortization	224	44,022	2,061
Deferred financing costs amortization and write offs	4,587	3,373	1,717
Acquisition prepaid compensation amortization	0	506	4,457
Loss on extinguishment of debt	0	0	0
Loss (gain) from disposition of business	34,343	(25,520)	(7,500)
Deferred income taxes	(16,528)	92,171	(9,936)
Impairment related charges	9,143	4,352	12,955
Loss on minority equity investment	10,406	0	0
Changes in assets held for sale from discontinued operations	(6,644)	218	0
Other adjustments, net	1,463	2,400	1,083
Change in operating assets and liabilities:
Accounts receivable	38,679	(15,754)	(17,209)
Inventories	(2,166)	(4,094)	(24,708)
Prepaid expenses and other assets	(10,585)	1,126	(2,412)
Accounts payable	(2,609)	3,449	(1,075)
Accrued and other liabilities	2,347	(15,176)	10,862
Income taxes	(3,064)	7,615	(6,473)
Net cash from operating activities	36,293	61,050	79,232
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of businesses, net	(1,000)	(270,008)	(85,517)
Purchases of property and equipment	(53,044)	(32,804)	(31,326)
Sale of assets	1,274	215	0
Proceeds from sales and maturities of short-term investments	100,375	44,555	51,573
Purchases of short-term investments	(114,461)	(105,048)	(36,316)
Purchases of other investments and intellectual property	(5,000)	0	(777)
Proceeds associated with divested business and discontinued operations	4,737	25,520	7,500
Net cash used in investing activities	(67,119)	(337,570)	(94,863)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from notes payable	0	96,558	247,625
Payments of financing costs	505	9,077	0
Proceeds from stock option exercises and employee stock purchases	6,957	8,281	5,460
Payments on notes payable	(6,885)	(4,747)	(4,138)
Payments of capital leases and assumed debt	(713)	(1,137)	(9,938)
Repurchase of common stock	(6,828)	(18,534)	(9,995)
Proceeds from corporate facility financing obligation	4,000	0	0
Other adjustments, net	(477)	2,309	(1,660)
Net cash (used in) from financing activities	(4,451)	73,653	227,354
Foreign currency effect on cash	(151)	(6)	(1,058)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(35,428)	(202,873)	210,665
CASH AND CASH EQUIVALENTS — Beginning of year	130,104	332,977	122,312
CASH AND CASH EQUIVALENTS — End of year	94,676	130,104	332,977
Supplemental disclosure of non-cash activities
Equity interests issued and issuable	$ 0	$ 465,082	$ 0

Description of Business

Description of Business	12 Months Ended
	Sep. 28, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	DESCRIPTION OF BUSINESS MACOM Technology Solutions Holdings, Inc. (the Company) was incorporated in Delaware on March 25, 2009. We are a leading provider of high-performance analog semiconductor solutions that enable next-generation Internet applications, the cloud connected apps economy, and the modern, networked battlefield across the radio frequency (RF), microwave, millimeterwave and lightwave spectrum. We design, develop, manufacture and have manufactured differentiated, high-value products for customers who demand high performance, quality and reliability.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Sep. 28, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation, Basis of Presentation and Reclassification —We have one reportable segment, semiconductors and modules. The accompanying consolidated financial statements include our accounts and the accounts of our majority-owned subsidiaries. Certain prior period financial statement amounts, such as deferred revenue and cash flow line item presentation have been adjusted to conform to currently reported presentations . All intercompany balances and transactions have been eliminated in consolidation. We have a 52- or 53-week fiscal year ending on the Friday closest to the last day of September. The fiscal years 2018 , 2017 and 2016 included 52 weeks. To offset the effect of holidays, for fiscal years in which there are 53 weeks, we typically include the extra week arising in our fiscal years in the first quarter. Use of Estimates —The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the U.S. requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities during the reporting periods, the reported amounts of revenue and expenses during the reporting periods and the disclosure of contingent assets and liabilities at the date of the financial statements. On an ongoing basis, we base estimates and assumptions on historical experience, currently available information and various other factors that management believes to be reasonable under the circumstances. Actual results may differ from these estimates and assumptions. Divested Businesses and Discontinued Operations— In the first quarter of fiscal year 2018, we divested AppliedMicro's compute business (the Compute business). In the third quarter of fiscal year 2018, we divested our Japan-based long-range optical subassembly business (the LR4 business). The operating results of the LR4 business have been reflected in our continuing operations up through the May 10, 2018 sale date with the $34.3 million loss on disposal recorded as other expense. The operating results of the Compute business are reflected in discontinued operations. See Note 21 - Divested Business and Discontinued Operations for additional information. Foreign Currency Translation and Remeasurement —Our consolidated financial statements are presented in U.S. dollars. While the majority of our foreign operations use the U.S. dollar as the functional currency, the financial statements of our foreign operations for which the functional currency is not the U.S. dollar are translated into U.S. dollars at the exchange rates in effect at the balance sheet dates (for assets and liabilities) and at average exchange rates (for revenue and expenses). The unrealized translation gains and losses on the net investment in these foreign operations are accumulated as a component of other comprehensive (loss) income. The financial statements of our foreign operations where the functional currency is the U.S. dollar, but where the underlying transactions are transacted in a different currency, are remeasured at the exchange rate in effect at the balance sheet date with respect to monetary assets and liabilities. Nonmonetary assets and liabilities, such as inventories and property and equipment and related statements of operations accounts, such as cost of revenue and depreciation, are remeasured at historical exchange rates. Revenue and expenses, other than cost of revenue, amortization and depreciation, are translated at the average exchange rate for the period in which the transaction occurred. The net gains and losses on foreign currency remeasurement are reflected in selling, general and administrative expense in the accompanying consolidated statements of operations. Net foreign exchange transaction gains and losses for all periods presented were not material. Cash and Cash Equivalents —Cash equivalents are primarily composed of short-term, highly-liquid instruments with an original maturity of three months or less and consist primarily of money market funds. Investments — Short-term investments: We classify our short-term investments as available-for-sale. Our investments classified as available-for-sale are recorded at fair value based upon third party pricing at period end. Unrealized gains and losses that are deemed temporary in nature are recorded in accumulated other comprehensive income and loss as a separate component of stockholders’ equity. A decline in the fair value of any security below cost that is deemed other than temporary results in a charge to earnings and the corresponding establishment of a new cost basis for the security. Premiums and discounts are amortized (accreted) over the life of the related security as an adjustment to its yield. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of investments sold. Other investments: We use the equity method to account for investments in companies if the investment provides us with the ability to exercise significant influence over operating and financial policies of the investee. Our proportionate share of the net income (loss) resulting from these investments are reported within the Other (expense) income line in our Consolidated Statements of Operations. The carrying value of our equity method investments is reported in Other investments in our Consolidated Balance Sheets. Other investments that are not controlled, and over which we do not have the ability to exercise significant influence, are accounted for under the cost method and reported in Other investments in our Consolidated Balance Sheets. Our equity method investments are reported at cost and adjusted each period for our share of the investee’s income or loss and dividends paid, if any, while cost method investments are carried at cost. The entities do not have a readily determinable fair value and are periodically evaluated for impairment. An impairment loss would be recorded whenever a decline in value of an investment below its carrying amount is determined to be other than temporary. Refer to Note 4 - Investments, for additional information. Inventories —Inventories are stated at the lower of cost or net realizable value. We use a combination of standard cost and moving weighted-average cost methodologies to determine the cost basis for our inventories, approximating a first-in, first-out basis. The standard cost of finished goods and work-in-process inventory is composed of material, labor and manufacturing overhead, which approximates actual cost. In addition to stating inventory at the lower of cost or net realizable value, we also evaluate inventory each reporting period for excess quantities and obsolescence, establishing reserves when necessary based upon historical experience, assessment of economic conditions and expected demand. Once recorded, these reserves are considered permanent adjustments to the carrying value of inventory. Property and Equipment —Property and equipment are stated at cost, less accumulated depreciation and amortization. Expenditures for maintenance and repairs are charged to expense as incurred, whereas major improvements that significantly extend the useful life of the assets are capitalized as additions to property and equipment. Property and equipment are depreciated or amortized using the straight-line method over the following estimated useful lives: Asset Classification Estimated Useful Life In Years Buildings and improvements 20 – 40 Capital lease assets 5 - 20 Machinery and equipment 2 – 7 Computer equipment and software 2 – 5 Furniture and fixtures 7 – 10 Leasehold improvements Shorter of useful life or term of lease Goodwill and Indefinite-Lived Intangible Assets —We have goodwill and certain intangible assets with indefinite lives which are not subject to amortization; these are reviewed for impairment annually as of the end of our August fiscal month end and more frequently if events or changes in circumstances indicate that the assets may be impaired. For our assessment of goodwill impairment, we compare the carrying value of the reporting unit to the fair value of the Company. For our assessment of in-service indefinite-lived assets we compare the carrying value of the asset to the estimated fair value of the asset. For indefinite-lived assets not in service, such as in-process research and development, we perform both qualitative and quantitative assessments using an assumption of "more likely than not" to determine if there are any impairment indicators. If impairment exists, a loss is recorded to write down the value of the assets to their implied fair values. During the fiscal year ended September 29, 2017, we recorded impairment charges of $4.4 million related to indefinite-lived intangible assets. S ee Note 16 - Intangible Assets , for further detail of these impairment charges. There were no significant expenses related to abandoned in-process research and development projects in any other period presented. Impairment of Long-Lived Assets —Long-lived assets include property and equipment and definite-lived intangible assets subject to amortization. We evaluate long-lived assets for recoverability when events or changes in circumstances indicate that their carrying amounts may not be recoverable. Circumstances which could trigger a review include, but are not limited to, significant decreases in the market price of the asset or asset group, significant adverse changes in the business climate or legal factors, the accumulation of costs significantly in excess of the amount originally expected for the acquisition or construction of the asset, current period cash flow or operating losses combined with a history of losses or a forecast of continuing losses associated with the use of the asset and a current expectation that the asset will more likely than not, be sold or disposed of significantly before the end of its previously estimated useful life. In evaluating a long-lived asset for recoverability, we estimate the undiscounted cash flows expected to result from our use and eventual disposition of the asset. If the sum of the expected undiscounted cash flows is less than the carrying amount of the asset, an impairment loss, equal to the excess of the carrying amount over the fair value of the asset, is recognized. In fiscal year 2018, we recorded impairment charges of $6.6 million , including $4.6 million related to property and equipment and $2.0 million related to other assets designated for future use with Zhongxing Telecommunications Equipment Corporation (ZTE), as a result of the Bureau of Industry and Security (BIS) denial order on April 15, 2018. In fiscal year 2016 we recorded impairment charges of $ 13.8 million related to our strategic decision to exit a product line and end programs associated with our GaN-on Silicon Carbide (GaN-on-SiC) license and technology transfer. There were no impairments of long-lived assets in fiscal year 2017. Intangible assets related to in-process research and development acquired are not amortized until the underlying asset begins revenue-generating activity, at which time it is amortized over its estimated useful life. Intangibles related to abandoned in-process research and development projects are expensed in the period the project is abandoned. Other Intangible Assets —Our other intangible assets, including acquired technology and customer relationships, are definite-lived assets and are subject to amortization. We amortize definite-lived assets over their estimated useful lives, which range from five to fourteen years, generally based on the pattern over which we expect to receive the economic benefit from these assets. Revenue Recognition —We recognize revenue when: (i) persuasive evidence of an arrangement exists; (ii) delivery or services have been rendered; (iii) the price is fixed or determinable; and (iv) collectability is reasonably assured. We recognize revenue with the transfer of title and risk of loss and provide for reserves for returns and other allowances. We generally do not provide customers other than distributors the right to return product, with the exception of warranty related matters. Shipping and handling fees billed to customers are recorded as revenue while the related costs are classified as a component cost of revenue. We provide warranties for certain products and accrue the estimated costs of warranty claims in the period the related revenue is recorded. Product warranties generally have terms of 12 months and cover nonconformance with specifications and defects in material or workmanship. For sales to distributors, our warranty generally begins when the product is resold by the distributor. The liability is based on estimated costs to fulfill customer product warranty obligations and utilizes historical product failure rates. Should actual warranty obligations differ from estimates, revisions to the warranty liability may be required. We have agreements with some distribution customers for various programs, including compensation, volume-based pricing, obsolete inventory, new products and stock rotation. Sales to these distribution customers, as well as the existence of compensation programs, are in accordance with terms set forth in written agreements with these distribution customers. In general, credits allowed under these programs are capped based upon individual distributor agreements. We record charges associated with these programs as a reduction of revenue at the time of sale with a corresponding adjustment to accounts receivable based upon historical activity. Our policy is to use a 12 months rolling historical experience rate and an estimated general reserve percentage in order to estimate the necessary allowance to be recorded. We record deferred revenue when payments are received or due in advance of our performance under a contract, which is then recognized as revenue once the performance obligations are satisfied. Research and Development Costs —Costs incurred in the research and development of products are expensed as incurred. Income Taxes —Deferred tax assets and liabilities are recognized based on temporary differences between the financial reporting and income tax bases of assets and liabilities, using rates anticipated to be in effect when such temporary differences reverse. A valuation allowance against net deferred tax assets is required if, based upon the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We provide reserves for potential payments of tax to various tax authorities related to uncertain tax positions and other issues. Reserves are based on a determination of whether and how much of a tax benefit is taken by us in our tax filings or positions that are more likely than not to be realized following an examination by taxing authorities. We recognize the financial statement benefit of an uncertain tax position only after considering the probability that a tax authority would sustain the position in an examination. For tax positions meeting a “more-likely-than-not” threshold, the amount recognized in the financial statements is the benefit expected to be realized upon settlement with the tax authority. For tax positions not meeting the threshold, no financial statement benefit is recognized. Potential interest and penalties associated with such uncertain tax positions are recorded as a component of income tax expense. Earnings Per Share —Basic net (loss) income per share is computed by dividing net (loss) income by the weighted-average number of common shares outstanding during the period, excluding the dilutive effect of common stock equivalents. Diluted net (loss) income per share reflects the dilutive effect of common stock equivalents, such as stock options, warrants and restricted stock units, using the treasury stock method. Fair Value Measurements —Financial assets and liabilities are measured at fair value. Fair value is an exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability at the measurement date under current market conditions in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, we group financial assets and liabilities in a three-tier fair value hierarchy, according to the inputs used in measuring fair value as follows: Level 1—observable inputs such as quoted prices in active markets for identical assets and liabilities; Level 2—inputs other than quoted prices in active markets that are observable either directly or indirectly, such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical assets and liabilities in markets that are not active and model-based valuation techniques for which significant assumptions are observable in active markets; and, Level 3—unobservable inputs for which there is little or no market data, requiring us to develop our own assumptions for model-based valuation techniques. This hierarchy requires us to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. Money market funds are actively traded and consist of highly liquid investments with original maturities of 90 days or less. They are measured at their net asset value and classified as Level 1. Corporate and agency bonds and commercial paper are categorized as Level 2 assets except where sufficient quoted prices exist in active markets, in which case such securities are categorized as Level 1 assets. These securities are valued using third-party pricing services. These services may use, for example, model-based pricing methods that utilize observable market data as inputs. We generally use quoted prices for recent trading activity of assets with similar characteristics to the debt security or bond being valued. The securities and bonds priced using such methods are generally classified as Level 2. Broker dealer bids or quotes on securities with similar characteristics may also be used. The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to the short-term nature of these assets and liabilities. Contingent Consideration —We estimate and record at the acquisition date, the fair value of contingent consideration making up part of the purchase price consideration for acquisitions. Additionally, at each reporting period, we estimate the change in the fair value of contingent consideration and any change in fair value is recognized in the consolidated statements of operations. We estimate the fair value of contingent consideration by discounting the associated expected cash flows, using a probability-weighted, discounted cash flow model. The estimate of the fair value of contingent consideration requires subjective assumptions to be made regarding future operating results, discount rates and probabilities assigned to various potential operating result scenarios. Share-Based Compensation —We account for all share-based compensation arrangements using the fair value method. We recognize compensation expense over the requisite service period of the award, which is generally the vesting period, using the straight-line method for service-based awards and the accelerated method for performance-based awards, and providing that the minimum amount of compensation recorded is equal to the vested portion of the award. We record the expense in the consolidated statements of operations in the same manner in which the award recipients’ salary costs are classified. For restricted stock awards with service conditions we use the closing stock price on the date of grant to estimate the fair value of the awards. We use the Black-Scholes option-pricing model to estimate the fair value of stock options with service and performance conditions, inclusive of assumptions for risk-free interest rates, dividends, expected terms and estimated volatility. We use the Monte Carlo Simulation analysis to estimate the fair value of stock options with market conditions, inclusive of assumptions for risk free interest rates, expected term, expected volatility and the target price. We derive the risk-free interest rate assumption from the U.S. Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to the expected term of the award being valued. We base the assumed dividend yield on its expectation of not paying dividends in the foreseeable future. We calculate the weighted-average expected term of the options using the simplified method, which is a method of applying a formula that uses the vesting term and the contractual term to compute the expected term of a stock option. The decision to use the simplified method is based on a lack of relevant historical data, due to our limited operating experience. In addition, we calculate our estimated volatility using our historical stock price volatility data. In fiscal year 2018 we adopted Accounting Standards Update (ASU) 2016-09, Compensation - Stock Compensation (ASU 2016-09), and upon adoption we elected to account for forfeitures when they occur. Prior to the adoption of ASU 2016-09 the accounting for share-based compensation required forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differed from those estimates. See the Recent Accounting Pronouncements section below for additional detail on the adoption of ASU 2016-09. Share-based awards that are settled in cash are recorded as liabilities. The measurement of the liability and compensation cost for these awards is based on the fair value of the award, and is recorded in operating income over the award’s vesting period. Changes in our payment obligation prior to the settlement date of a stock-based award are recorded as compensation expense in operating income in the period of the change. The final payment amount for such awards is established on the date of the exercise of the award by the employee. Guarantees and Indemnification Obligations —We enter into agreements in the ordinary course of business with, among others, customers, distributors and original equipment manufacturers (OEM). Most of these agreements require us to indemnify the other party against third-party claims alleging that a Company product infringes a patent and/or copyright. Certain agreements in which we grant limited licenses to Company intellectual property require us to indemnify the other party against third-party claims alleging that the use of the licensed intellectual property infringes a third-party's intellectual property. Certain of these agreements require us to indemnify the other party against certain claims relating to property damage, personal injury or the acts or omissions, its employees, agents or representatives. In addition, from time to time, we have made certain guarantees in the form of warranties regarding the performance of Company products to customers. We have agreements with certain vendors, creditors, lessors and service providers pursuant to which we have agreed to indemnify the other party for specified matters, such as acts and omissions, its employees, agents or representatives. We have procurement or license agreements with respect to technology used in our products and agreements in which we obtain rights to a product from an OEM. Under some of these agreements, we have agreed to indemnify the supplier for certain claims that may be brought against such party with respect to our acts or omissions relating to the supplied products or technologies. Our certificate of incorporation and agreements with certain of our directors and officers and certain of our subsidiaries’ directors and officers provide them indemnification rights, to the extent legally permissible, against liabilities incurred by them in connection with legal actions in which they may become involved by reason of their service as a director or officer. As a matter of practice, we have maintained director and officer liability insurance coverage, including coverage for directors and officers of acquired companies. We have not experienced any losses related to these indemnification obligations in any period presented and no claims with respect thereto were outstanding as of September 28, 2018 and September 29, 2017 . We do not expect significant claims related to these indemnification obligations and, consequently, have concluded that the fair value of these obligations is negligible. No liabilities related to indemnification liabilities have been established. Recent Accounting Pronouncements — Pronouncements Adopted in Fiscal Year 2018 In March 2016, the Financial Accounting Standards Board (FASB) issued ASU 2016-09, which simplifies several aspects of the accounting for employee share-based payment transactions for both public and nonpublic entities. We adopted this ASU as of September 30, 2017. Prior to ASU 2016-09, the accounting for share-based compensation required forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. ASU 2016-09 allows an entity to make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest or account for forfeitures when they occur. ASU 2016-09 requires an entity that elects to account for forfeitures when they occur to apply the accounting change on a modified retrospective basis as a cumulative-effect adjustment to retained earnings as of the date of adoption. We elected to account for forfeitures when they occur, and recorded a $1.0 million cumulative-effect adjustment to beginning retained earnings as of September 30, 2017. We did not record any adjustments to retained earnings for the tax effect of the adoption of ASU 2016-09 as we have a full valuation allowance position against our U.S. deferred tax asset. ASU 2016-09 requires all excess tax benefits and tax deficiencies to be recorded in the consolidated income statement on a prospective basis when the awards vest or are settled. Due to our full U.S. valuation allowance, ASU 2016-09 had no impact to our tax expense for fiscal year 2018. Pronouncements for Adoption in Subsequent Periods In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). In March, April, May and December 2016, the FASB issued additional guidance related to Topic 606. The new standard superseded nearly all existing revenue recognition guidance. Under Topic 606, an entity is required to recognize revenue upon transfer of promised goods or services to customers in an amount that reflects the expected consideration to be received in exchange for those goods or services. Topic 606 defines a five-step process in order to achieve this core principle, which may require the use of judgment and estimates, and also requires expanded qualitative and quantitative disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers, including significant judgments and estimates used. The new standard also defines accounting for certain costs related to origination and fulfillment of contracts with customers, including whether such costs should be capitalized. The new standard permits adoption either by using (i) a full retrospective approach for all periods presented in the period of adoption or (ii) a modified retrospective approach where the new standard is applied in the financial statements starting with the year of adoption. Under both approaches, cumulative impact of the adoption is reflected as an adjustment to retained earnings (accumulated deficit) as of the earliest date presented in accordance with the new standard. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers: Deferral of the Effective Date , which delayed the effective date of the new standard from January 1, 2017 to January 1, 2018. We plan to implement the new guidance as of September 29, 2018, the beginning of our next fiscal year, using the modified retrospective approach, applied to those contracts that were not completed as of that date. We developed a project plan for the implementation of the guidance, including a review of our revenue streams to identify any differences in the timing, measurement or presentation of revenue recognition and costs to obtain or fulfill the contracts. We have completed our assessment of the impacts of the standard, including any impacts from issued amendments, and have determined that the cumulative effect of the adoption of this new standard is not material. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . This update makes amendments to the guidance in U.S. GAAP on the classification and measurement of financial instruments. The new standard significantly revises an entity's accounting related to (1) the classification and measurement of investments in equity securities and (2) the presentation of certain fair value changes for financial liabilities measured at fair value. It also amends certain disclosure requirements associated with the fair value of financial instruments. ASU 2016-01 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We do not expect the updated standard to have a material impact on our consolidated financial statements and related disclosures. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . In September 2017 and January and July of 2018, the FASB issued additional guidance related to Topic 842. The new standard increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. Certain qualitative and quantitative disclosures are required, as well as a retrospective recognition and measurement of impacted leases. The new guidance is effective for fiscal years and interim periods within those years beginning after December 15, 2018, with early adoption permitted. We are evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures and we anticipate that this new guidance will materially impact our financial statements as we have a significant number of operating leases. In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments . This update amends the guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For available for sale debt securities, credit losses should be measured in a manner similar to current GAAP; however, this update will require that credit losses be presented as an allowance rather than as a write-down. ASU 2016-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. We are evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures. In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments . This update addresses debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions and separately identifiable cash flows and application of the predominance principle. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We are evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures. In October 2016, the FASB issued ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inv

Acquisitions

Acquisitions	12 Months Ended
	Sep. 28, 2018
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Acquisition of Applied Micro Circuits Corporation— On January 26, 2017, we completed the acquisition of Applied Micro Circuits Corporation (AppliedMicro), a global provider of silicon solutions for next-generation cloud infrastructure and Cloud Data Centers, as well as connectivity products for edge, metro and long-haul communications equipment (the AppliedMicro Acquisition). We acquired AppliedMicro in order to expand our business in enterprise and Cloud Data Center applications. In connection with the AppliedMicro Acquisition, we acquired all of the outstanding common stock of AppliedMicro for total consideration of $695.4 million , which included cash paid of $287.1 million , less $56.8 million of cash acquired, and equity issued at a fair value of $465.1 million . In conjunction with the equity issued, we granted vested out-of-the-money stock options and unvested restricted stock units to replace outstanding vested out-of-the-money stock options and unvested restricted stock units of AppliedMicro. The total fair value of granted vested out-of-money stock options and unvested restricted stock units was $14.5 million , of which $9.3 million was attributable to pre-combination service and was included in the total consideration transferred. We funded the AppliedMicro Acquisition with cash on hand and short-term investments. There were no transaction costs for the fiscal year ended September 28, 2018, and during the fiscal year ended September 29, 2017, we recorded transaction costs of $11.9 million . We recorded transaction costs related to the acquisition in selling, general and administrative expense, except for $1.0 million related to equity issuance costs that were recorded to additional paid-in capital. The AppliedMicro Acquisition was accounted for as a stock purchase and the operations of AppliedMicro have been included in our consolidated financial statements since the date of acquisition. We recognized the AppliedMicro assets acquired and liabilities assumed based upon the fair value of such assets and liabilities measured as of the date of acquisition. The aggregate purchase price for AppliedMicro has been allocated to the tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair value at the date of acquisition. The excess of the purchase price over the fair value of the acquired net assets represents cost and revenue synergies specific to the Company, as well as non-capitalizable intangible assets, such as the employee workforce acquired, and has been allocated to goodwill, none of which will be tax deductible. In connection with the acquisition of AppliedMicro, we entered into a plan to divest a portion of AppliedMicro's business specifically related to its compute business (the "Compute business"). The divestiture of the Compute business was completed on October 27, 2017. See Note 21 - Divested Business and Discontinued Operations for further details of the divestiture. The following table summarizes the total estimated acquisition consideration (in thousands): Cash consideration paid to AppliedMicro common stockholders $ 287,060 Common stock issued (9,544,125 shares of our common stock at $47.53 per share) 453,632 Equity consideration for vested "in-the-money" stock options and unvested restricted stock units 2,143 Fair value of the replacement equity awards attributable to pre-acquisition service 9,307 Total consideration paid, less cash acquired $ 752,142 We finalized the purchase accounting during the fiscal quarter ended December 29, 2017. The final purchase price allocation is as follows (in thousands): As Reported Allocation Adjustments Final Allocation September 29, 2017 Current assets $ 70,434 $ (553 ) $ 69,881 Intangible assets 412,848 — 412,848 Assets held for sale 40,944 — 40,944 Other assets 9,800 — 9,800 Total assets acquired 534,026 (553 ) 533,473 Liabilities held for sale 4,444 — 4,444 Other liabilities 17,627 651 18,278 Total liabilities assumed 22,071 651 22,722 Net assets acquired 511,955 (1,204 ) 510,751 Consideration: Cash paid upon closing 230,298 — 230,298 Common stock issued 455,775 — 455,775 Equity instruments issued 9,307 — 9,307 Total consideration $ 695,380 $ — $ 695,380 Goodwill $ 183,425 $ 1,204 $ 184,629 The components of the acquired intangible assets were as follows (in thousands): Included In Assets Held For Sale Included In Retained Business Useful Lives (Years) Developed technology $ 9,600 $ 78,448 7 years Customer relationships — 334,400 14 years $ 9,600 $ 412,848 The overall weighted-average life of the identified intangible assets acquired in the AppliedMicro Acquisition is estimated to be 12.7 years and the assets are being amortized over their estimated useful lives based upon the pattern over which we expect to receive the economic benefit from these assets. The following is a summary of AppliedMicro revenue and earnings included in our accompanying consolidated statements of operations for the fiscal year ended September 29, 2017 (in thousands): Amount Revenue $ 110,117 Loss from continuing operations (27,222 ) Loss from discontinued operations (44,599 ) The pro forma statements of operations data for the fiscal year ended September 29, 2017, below, gives effect to the AppliedMicro Acquisition, described above, as if it had occurred at October 2, 2015. These amounts have been calculated after applying our accounting policies and adjusting the results of AppliedMicro to reflect: transaction costs, retention compensation expense, the impact of the step-up to the value of acquired inventory, as well as the additional intangible amortization that would have been charged assuming the fair value adjustments had been applied and incurred since October 2, 2015. This pro forma data is presented for informational purposes only and does not purport to be indicative of our future results of operations. Fiscal Year Ended September 29, 2017 September 30, 2016 Revenue $ 755,728 $ 707,299 Loss from continuing operations (104,828 ) (53,613 ) Loss from discontinued operations (43,734 ) (72,730 ) Acquisition of Assets of Picometrix LLC— On August 9, 2017, we completed the acquisition of certain assets of Picometrix LLC (Picometrix), a supplier of optical-to-electrical converters for Cloud Data Center infrastructure (the Picometrix Acquisition). We acquired Picometrix in order to expand our business in enterprise and Cloud Data Center applications. The purchase consideration was $33.5 million , comprised of an upfront cash payment of $29.5 million , and $4.0 million placed in escrow for potential satisfaction of certain indemnification obligations that may arise from the closing date through December 15, 2018. For the fiscal year ended September 28, 2018, we recorded no transaction costs. For the fiscal year ended September 29, 2017, we recorded transaction costs of $0.2 million in selling, general and administrative expense. The Picometrix Acquisition was accounted for as an asset purchase business acquisition, and the operations of Picometrix have been included in our consolidated financial statements since the date of acquisition. We recognized the Picometrix assets acquired based upon the fair value of such assets measured as of the date of acquisition. The aggregate purchase price for the Picometrix assets has been allocated to the tangible and identifiable intangible assets acquired based on their estimated fair value at the date of acquisition. The excess of the purchase price over the fair value of the acquired assets represents cost and revenue synergies specific to the Company, as well as non-capitalizable intangible assets, such as the employee workforce acquired, and has been allocated to goodwill, all of which will be tax deductible. We finalized the purchase accounting during the fiscal quarter ended June 29, 2018. The final purchase price allocation is as follows (in thousands): As Reported Allocation Adjustments Final Allocation September 29, 2017 Current assets $ 7,375 $ (1,088 ) $ 6,287 Intangible assets 19,000 — 19,000 Other assets 3,301 (81 ) 3,220 Total assets acquired 29,676 (1,169 ) 28,507 Current liabilities 2,169 142 2,311 Other liabilities 190 275 465 Total liabilities assumed 2,359 417 2,776 Net assets acquired 27,317 (1,586 ) 25,731 Consideration: Cash paid upon closing, net of cash acquired 33,500 — 33,500 Goodwill $ 6,183 $ 1,586 $ 7,769 The pro forma financial information for fiscal year 2017, including revenue and net income, is immaterial, and has not been separately presented. Other Acquisitions — On July 31, 2017, we completed the acquisition of certain assets of Antario Technologies, Inc. (Antario) a privately-held company based in Taiwan and in California. The total cash consideration was approximately $5.8 million , of which $4.8 million was paid upon closing, and approximately $1.0 million was withheld for potential satisfaction of certain indemnification obligations that may arise from the closing date through July 31, 2018. We finalized the purchase accounting during the fiscal quarter ended December 29, 2017, which resulted in goodwill of $1.6 million and intangible assets, including acquired technology and customer relationships, of $4.1 million . The Antario transaction was accounted for as an asset purchase business combination and the operations have been included in our consolidated financial statements since the acquisition date. Pro forma financial disclosures are not presented herein as the financial results of Antario are considered immaterial. On May 26, 2017, we completed the acquisition of Triple Play Communications Corporation (TPC) a privately-held company based in Melbourne, Florida. The total cash consideration was approximately $2.6 million , of which $2.2 million was paid upon closing, and approximately $0.4 million was withheld for potential satisfaction of certain indemnification obligations from the closing date through November 23, 2018. We finalized the purchase accounting during the fiscal quarter ended December 29, 2017, which resulted in goodwill of $3.7 million and intangible assets, including customer relationships, of $0.2 million . TPC was accounted for as a stock purchase business combination and the operations have been included in our consolidated financial statements since the acquisition date. Pro forma financial disclosures are not presented herein as the financial results of TPC are considered immaterial. Acquisition of FiBest Limited — On December 9, 2015, we completed the acquisition of FiBest Limited (FiBest) a Japan-based merchant market component supplier of optical sub-assemblies (FiBest Acquisition). We acquired FiBest to expand our position in optical networking components. In connection with the FiBest Acquisition, all of the outstanding equity interests (including outstanding options) of FiBest were exchanged for aggregate consideration of $ 59.1 million including cash of $ 47.5 million and assumed debt of $ 11.6 million . We funded the FiBest Acquisition with cash on-hand. There were no transaction costs recorded for the fiscal year ended September 29, 2017. For the fiscal year ended September 30, 2016, we recorded transaction costs of $2.7 million as selling, general and administrative expense related to this acquisition. The FiBest Acquisition was accounted for as a stock purchase business combination and the operations of FiBest have been included in our consolidated financial statements since the date of acquisition. We recognized the FiBest assets acquired and liabilities assumed based upon the fair value of such assets and liabilities measured as of the date of acquisition. The aggregate purchase price for FiBest is being allocated to the tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair values at the date of acquisition. The excess of the purchase price over the fair value of the acquired net assets represents cost and revenue synergies specific to the Company, as well as non-capitalizable intangible assets, such as the employee workforce acquired, and has been allocated to goodwill, none of which will be tax deductible. The final allocation of purchase price as of December 30, 2016, is as follows (in thousands): Final Allocation Current assets $ 10,445 Intangible assets 45,650 Other assets 3,317 Total assets acquired 59,412 Debt 11,627 Deferred income taxes 11,552 Other liabilities 4,294 Total liabilities assumed 27,473 Net assets acquired 31,939 Consideration: Cash paid upon closing, net of cash acquired 47,517 Goodwill $ 15,578 The components of the acquired intangible assets on a preliminary basis were as follows (in thousands): Amount Useful Lives (Years) Developed technology $ 9,400 7 Customer relationships 36,250 10 $ 45,650 The overall weighted-average life of the identified intangible assets acquired in the FiBest Acquisition is estimated to be 9.4 years and the assets are being amortized over their estimated useful lives based upon the pattern over which we expect to receive the economic benefit from these assets. The following is a summary of FiBest revenue and earnings included in our accompanying consolidated statements of operations for the fiscal year ended September 30, 2016 (in thousands): Amount Revenue $ 30,540 Loss before income taxes (4,616 ) Unaudited Supplemental Pro Forma Data— The pro forma statements of operations data for the fiscal year ended September 30, 2016 and October 2, 2015 below give effect to the FiBest Acquisition, described above, as if it had occurred at October 4, 2014. These amounts have been calculated after applying our accounting policies and adjusting the results of FiBest to reflect; transaction costs, retention compensation expense, the impact of the step-up to the value of acquired inventory, as well as the additional intangible amortization that would have been charged assuming the fair value adjustments had been applied and incurred since October 4, 2014. This pro forma data is presented for informational purposes only and does not purport to be indicative of our future results of operations. Fiscal Year Ended September 30, 2016 Revenue $ 551,964 Net (loss) income (3,324 ) Acquisition of Aeroflex/Metelics Inc. — On December 14, 2015, we acquired Aeroflex/Metelics, Inc. (Metelics), a diode supplier for aggregate cash consideration of $37.1 million , subject to customary working capital and other adjustments (Metelics Acquisition). We acquired Metelics to expand our diode business. We funded the acquisition with cash on hand. The Metelics Acquisition was accounted for as a stock purchase business combination and the operations of Metelics have been included in our consolidated financial statements since the date of acquisition. For the fiscal year ended September 29, 2017, there were no transaction costs recorded related to this acquisition. For the fiscal year ended September 30, 2016, we recorded transaction costs of $0.5 million as selling, general and administrative expenses related to this acquisition. We recognized the Metelics assets acquired and liabilities assumed based upon the fair value of such assets and liabilities measured as of the date of acquisition. The aggregate purchase price for Metelics is being allocated to the tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair values at the date of acquisition. The excess of the purchase price over the fair value of the acquired net assets represents cost and revenue synergies specific to the Company, as well as non-capitalizable intangible assets, such as the employee workforce acquired, and has been allocated to goodwill, which will be tax deductible due to a 338(h)(10) election. We finalized our allocation of purchase price during the fiscal quarter ended December 30, 2016. The final allocation of purchase price as of December 30, 2016, is as follows (in thousands): Final Allocation Current assets $ 12,614 Intangible assets 20,900 Other assets 3,089 Total assets acquired 36,603 Other liabilities 7,201 Total liabilities assumed 7,201 Net assets acquired 29,402 Consideration: Cash paid upon closing, net of cash acquired 37,125 Goodwill $ 7,723 The components of the acquired intangible assets on a preliminary basis were as follows (in thousands): Amount Useful Lives (Years) Developed technology $ 1,000 7 Customer relationships 19,900 10 $ 20,900 The overall weighted-average life of the identified intangible assets acquired in the Metelics Acquisition is estimated to be 9.9 years and the assets are being amortized over their estimated useful lives based upon the pattern over which we expect to receive the economic benefit from these assets. The following is a summary of Metelics revenue and earnings included in our accompanying consolidated statements of operations for the fiscal year ended September 30, 2016 (in thousands): Amount Revenue $ 33,552 Income before income taxes 3,372 Unaudited Supplemental Pro Forma Data— The pro forma statements of operations data for the fiscal year ended September 30, 2016, below, give effect to the Metelics Acquisition, described above, as if it had occurred at October 4, 2014. These amounts have been calculated after applying our accounting policies and adjusting the results of Metelics to reflect the transaction costs, the impact of the step-up to the value of acquired inventory, as well as, the additional intangible amortization that would have been charged assuming the fair value adjustments had been applied and incurred since October 4, 2014. This pro forma data is presented for informational purposes only and does not purport to be indicative of our future results of operations. Fiscal Year Ended September 30, 2016 Revenue $ 553,174 Net income 1,183

Investments

Investments	12 Months Ended
	Sep. 28, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	. INVESTMENTS All investments are short-term in nature and are invested in corporate bonds, commercial paper and agency bonds, and are classified as available-for-sale. The amortized cost, gross unrealized holding gains or losses and fair value of our available-for-sale investments by major investments type as of September 28, 2018 and September 29, 2017 are summarized in the tables below (in thousands): September 28, 2018 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value Corporate bonds $ 28,731 $ — $ (460 ) $ 28,271 Commercial paper 69,966 — (16 ) 69,950 Total investments $ 98,697 $ — $ (476 ) $ 98,221 September 29, 2017 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value Corporate bonds $ 26,366 $ 10 $ (166 ) $ 26,210 Commercial paper 57,943 4 (36 ) 57,911 Total investments $ 84,309 $ 14 $ (202 ) $ 84,121 The contractual maturities of available-for-sale investments were as follows (in thousands): September 28, 2018 Less than 1 year $ 70,200 Over 1 year 28,021 Total investments $ 98,221 Available-for-sale investments are reported at fair value and as such, their associated unrealized gains and losses are reported as a separate component of stockholders’ equity within accumulated other comprehensive income (loss). We have determined that the gross unrealized losses on available for sale securities at September 28, 2018 and September 29, 2017 are temporary in nature. We review our investments to identify and evaluate investments that have indications of possible impairment. The techniques used to measure the fair value of our investments are described in Note 5 - Fair Value . Factors considered in determining whether a loss is temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and our intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. Substantially all of our fixed income securities are rated investment grade or better. We received proceeds from sales of available-for-sale securities of $100.4 million and $44.6 million during the fiscal years 2018 and 2017 , respectively. Such sales resulted in gross realized losses of $0.3 million and $0.1 million during the fiscal years ended September 28, 2018 and September 29, 2017 , respectively, which have been recorded within other (expense) income. Other Investments — As of September 28, 2018 , we held two no n-marketable equity investments classified as other long-term investments. One of these is a minority investment in a preferred stock ownership of a privately held manufacturing corporation with preferred liquidation rights over other equity shares. This investment had a value of $5.0 million at the date of purchase and approximates the then current fair value. Since we do not have the ability to exercise significant influence or control over the investee we account for this investment at cost, which we evaluate for impairment at each balance sheet date and through September 28, 2018 no impairment has been recorded for this investment. In addition, we have a minority investment of less than 20.0% of the outstanding equity of a privately held limited liability corporation (Compute). This investment was acquired in conjunction with the divestiture of the Compute business during the fiscal quarter ended December 29, 2017, had an initial value of $36.5 million and is accounted for using the equity method. We have no obligation to provide further funding to Compute. This investment value is updated quarterly based on our proportionate share of the losses or earnings of Compute utilizing the equity method. During fiscal year 2018 , we recorded a $10.4 million loss associated with this investment as other expense in our consolidated statements of operations. As of September 28, 2018 , the carrying value of this investment is $26.1 million .

Fair Value

Fair Value	12 Months Ended
	Sep. 28, 2018
Fair Value Disclosures [Abstract]
Fair Value	FAIR VALUE We group our financial assets and liabilities measured at fair value on a recurring basis in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: Level 1 - Quoted prices in active markets for identical assets or liabilities. Level 2 - Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets with insufficient volume or infrequent transactions (less active markets) or model-driven valuations in which all significant inputs are observable or can be derived principally from, or corroborated with, observable market data. Level 3 - Fair value is derived from valuation techniques in which one or more significant inputs are unobservable, including assumptions and judgments made by us. Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis We measure certain assets and liabilities at fair value on a recurring basis such as our financial instruments. There have been no transfers between Level 1, 2 or 3 assets or liabilities during the fiscal year ended September 28, 2018 . Assets and liabilities measured at fair value on a recurring basis consist of the following (in thousands): September 28, 2018 Fair Value Active Markets for Identical Assets (Level 1) Observable Inputs (Level 2) Unobservable Inputs (Level 3) Assets Money market funds $ 253 $ 253 $ — $ — Commercial paper 69,950 — 69,950 — Corporate bonds 28,271 — 28,271 — Total assets measured at fair value $ 98,474 $ 253 $ 98,221 $ — Liabilities Contingent consideration $ 585 $ — $ — $ 585 Common stock warrant liability 13,129 — — 13,129 Total liabilities measured at fair value $ 13,714 $ — $ — $ 13,714 September 29, 2017 Fair Value Active Markets for Identical Assets (Level 1) Observable Inputs (Level 2) Unobservable Inputs (Level 3) Assets Money market funds $ 36 $ 36 $ — $ — Commercial paper 57,911 — 57,911 — Corporate bonds 26,210 — 26,210 — Total assets measured at fair value $ 84,157 $ 36 $ 84,121 $ — Liabilities Contingent consideration $ 1,679 $ — $ — $ 1,679 Warrant liability 40,775 — — 40,775 Total liabilities measured at fair value $ 42,454 $ — $ — $ 42,454 The quantitative information utilized in the fair value calculation of our Level 3 liabilities are as follows: Liabilities Valuation Technique Unobservable Input September 28, 2018 September 29, 2017 Contingent consideration Discounted cash flow Discount rate 9.2% 9.2% Probability of achievement 90% 70% - 100% Timing of cash flows 1 month 2 - 8 months Warrant liability Black-Scholes model Volatility 60.7% 44.9% Discount rate 2.81% 1.62% Expected life 2.2 years 3.2 years Exercise price $14.05 $14.05 Stock price $20.60 $44.61 Dividend rate —% —% The fair values of the contingent consideration liabilities were estimated based upon a risk-adjusted present value of the probability-weighted expected payments by us. Specifically, we considered base, upside and downside scenarios for the operating metrics upon which the contingent payments are to be based. Probabilities were assigned to each scenario and the probability-weighted payments were discounted to present value using risk-adjusted discount rates. The changes in assets and liabilities with inputs classified within Level 3 of the fair value hierarchy consist of the following (in thousands): Fiscal Year 2018 September 29, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 28, Contingent consideration $ 1,679 $ (394 ) $ — $ (700 ) $ — $ 585 Warrant liability $ 40,775 $ (27,646 ) $ — $ — $ — $ 13,129 Fiscal Year 2017 September 30, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 29, Contingent consideration $ 848 $ 180 $ 1,701 $ (1,050 ) $ — $ 1,679 Warrant liability $ 38,253 $ 2,522 $ — $ — $ — $ 40,775 Fiscal Year 2016 October 2, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 30, Contingent consideration $ 1,150 $ 98 $ — $ (400 ) $ — $ 848 Warrant liability $ 21,822 $ 16,431 $ — $ — $ — $ 38,253

Accounts Receivables Allowances

Accounts Receivables Allowances	12 Months Ended
	Sep. 28, 2018
Receivables [Abstract]
Accounts Receivables Allowances	ACCOUNTS RECEIVABLES ALLOWANCES Summarized below is the activity in our accounts receivable allowances including compensation credits and doubtful accounts as follows (in thousands): Fiscal Year 2018 2017 2016 Balance - beginning of year $ 9,410 $ 3,279 $ 5,745 Provision, net 15,465 29,512 10,453 Charge-offs (18,080 ) (23,381 ) (12,919 ) Balance - end of year $ 6,795 $ 9,410 $ 3,279 The balances at the end of fiscal years 2018 , 2017 and 2016 are comprised primarily of compensation credits of $6.3 million , $8.9 million and $3.0 million , respectively, and allowances for doubtful accounts of $0.2 million for fiscal year 2018 , $0.3 million for fiscal year 2017 and $0.2 million for fiscal year 2016 .

Inventories

Inventories	12 Months Ended
	Sep. 28, 2018
Inventory Disclosure [Abstract]
Inventories	INVENTORIES Inventories consist of the following (in thousands): September 28, 2018 September 29, 2017 Raw materials $ 71,408 $ 78,999 Work-in-process 13,466 13,962 Finished goods 37,963 43,113 Total $ 122,837 $ 136,074

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Sep. 28, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment consist of the following (in thousands): September 28, September 29, Construction in process 49,661 22,195 Machinery and equipment 174,638 160,955 Leasehold improvements 14,984 13,809 Furniture and fixtures 2,306 2,078 Capital lease assets 19,380 20,410 Computer equipment and software 17,317 16,539 Total property and equipment 278,286 235,986 Less accumulated depreciation and amortization (128,363 ) (104,967 ) Property and equipment — net $ 149,923 $ 131,019 In fiscal years 2018 and 2017 capital lease assets includes $17.1 million and $16.9 million , respectively, of assets related to our corporate facility lease obligation, with the remaining balance primarily related to leased equipment. Depreciation and amortization expense related to property and equipment for fiscal years 2018 , 2017 and 2016 was $ 30.7 million , $27.3 million and $20.4 million , respectively. Accumulated depreciation on capital lease assets for fiscal years 2018 and 2017 was $3.2 million and $2.3 million , respectively.

Debt

Debt	12 Months Ended
	Sep. 28, 2018
Debt Disclosure [Abstract]
Debt	DEBT As of September 28, 2018 , we are party to a credit agreement dated as of May 8, 2014 with a syndicate of lenders and Goldman Sachs Bank USA (Goldman Sachs), as administrative agent (as amended on February 13, 2015, August 31, 2016, March 10, 2017, May 19, 2017, May 2, 2018 and May 9, 2018, the “Credit Agreement”). As of September 28, 2018 , the Credit Agreement consisted of term loans with an original principal amount of $700.0 million (Term Loans) and a revolving credit facility with an aggregate borrowing capacity of $160.0 million (Revolving Facility). The Revolving Facility will mature in November 2021 and the Term Loans will mature in May 2024 and bear interest at: (i) for LIBOR loans for any interest period, a rate per annum equal to the LIBOR rate as determined by the administrative agent, plus an applicable margin of 2.25% ; and (ii) for base rate loans, a rate per annum equal to the greater of (a) the prime rate quoted in the print edition of the Wall Street Journal, Money Rates Section, (b) the federal funds rate plus one-half of 1.00% and (c) the LIBOR rate applicable to a one-month interest period plus 1.00% (but, in each case, not less than 1.00% ), plus an applicable margin of 1.25% . All principal amounts outstanding and interest rate information as of September 28, 2018 , for the Credit Agreement were as follows (in thousands, except rate data): Principal Outstanding LIBOR Rate Margin Effective Interest Rate Term loans $679,856 2.24% 2.25% 4.49% On May 2, 2018, we entered into an amendment to our Credit Agreement (the “May 2nd Amendment”) with the lenders party thereto and Goldman Sachs, as the administrative agent. The amendment extended the maturity of $130.0 million of borrowing availability under our existing Revolving Facility until November 2021, with the remaining $30.0 million of borrowing availability maturing in May 2019. Prior to the amendment, the entire $160.0 million of the Revolving Facility borrowing availability was scheduled to mature in May 2019. On May 9, 2018, we entered into another amendment to our Credit Agreement (the “May 9th Amendment”, together with the May 2nd Amendment, the "May 2018 Amendments") with the lenders party thereto and Goldman Sachs, as the administrative agent. The amendment extended the maturity of the remaining $30.0 million of commitments comprising the aggregate $160.0 million of borrowing availability under our existing Revolving Facility until November 2021. We incurred $0.5 million in connection with the May 2018 Amendments, which were recorded as deferred financing costs and are being amortized over the life of the Revolving Facility as interest expense. As of September 28, 2018 , approximately $10.9 million of deferred financing costs remain unamortized, of which $10.0 million related to the Term Loans is recorded as a direct reduction of the recognized debt liabilities in our accompanying consolidated balance sheet, and $0.9 million related to the Revolving Facility is recorded in other long-term assets in our accompanying consolidated balance sheet. The Term Loans are secured by a first priority lien on substantially all of our assets and provide that we must comply with certain financial and non-financial covenants. The Term Loans are payable in quarterly principal installments of approximately $1.7 million on the last business day of each calendar quarter, with the remainder due on the maturity date. In the event that we divest a business, the net cash proceeds of the divestment are generally required, subject to certain exceptions, to be applied to repayment of outstanding Term Loans except to the extent we reinvest such proceeds in assets useful for our business within 18 months of receiving the proceeds. If we enter into a binding agreement to reinvest such proceeds within 18 months of receiving them, we have until the later of 18 months following our receipt of the proceeds and 6 months following the date of such agreement to complete the reinvestment. As of September 28, 2018 , we had $160.0 million of borrowing capacity under our Revolving Facility. As of September 28, 2018 , the following remained outstanding on the Term Loans: Principal balance $ 679,856 Unamortized discount (4,625 ) Unamortized deferred financing costs (9,974 ) Total term loans 665,257 Current portion 6,885 Long-term, less current portion $ 658,372 As of September 28, 2018 , the minimum principal payments under the Term Loans in future fiscal years were as follows (in thousands): 2019 $ 6,885 2020 6,885 2021 6,885 2022 6,885 2023 6,885 Thereafter 645,431 Total $ 679,856 The fair value of the Term Loans was estimated to be approximately $689.2 million and $696.2 million as of September 28, 2018 and September 29, 2017 , respectively, and was determined using Level 2 inputs, including a quoted interest rate from a bank.

Capital Lease and Financing Obl

Capital Lease and Financing Obligations (Notes)	12 Months Ended
	Sep. 28, 2018
Capital Lease and Financing Obligations [Abstract]
Capital Leases in Financial Statements of Lessee Disclosure	10. CAPITAL LEASE AND FINANCING OBLIGATIONS Corporate Facility Financing Obligation On May 26, 2016, we entered into a Purchase and Sale Agreement (Purchase and Sale Agreement) with Calare Properties, Inc., a Delaware corporation (together with its affiliates, the Buyer), for the sale and subsequent leaseback of our corporate headquarters, located at 100 Chelmsford Street, Lowell, Massachusetts. The transactions contemplated by the Purchase Agreement closed on December 28, 2016, at which time we also entered into three lease agreements with the Buyer including: (1) a 20 -year leaseback of the facility located at 100 Chelmsford Street (the 100 Chelmsford Lease), (2) a 20 -year build-to-suit lease arrangement for the construction and subsequent lease back of a new facility to be located at 144 Chelmsford Street (the 144 Chelmsford Lease), and (3) a 14 -year building lease renewal of an adjacent facility at 121 Hale Street (the 121 Hale Lease, and together with the 100 Chelmsford Lease and the 144 Chelmsford Lease, the Leases). Because the transactions contemplated by the Purchase and Sale Agreement and the related Leases were negotiated and consummated at the same time and in contemplation of one another to achieve the same commercial objective, the transactions are accounted for by us as a single unit of accounting. In addition, the Leases were determined to represent a failed sale-leaseback due to our continuing involvement in the properties in the form of non-recourse financing. As a result, the Leases are accounted for under the financing method and we will be deemed the accounting owner under the arrangement, including the assets to be constructed under the 144 Chelmsford Lease. We will continue to recognize the existing building and improvements sold under the Purchase and Sale Agreement, capitalize the 121 Hale Street building as well as the assets constructed under the Leases, and depreciate the assets over the shorter of their estimated useful lives or the lease terms. The sale proceeds from the Purchase and Sale Agreement of $8.2 million (which includes $4.2 million in cash and $4.0 million in construction allowances) and the fair value of the 121 Hale Street building of $4.0 million were recognized as a financing obligation, which is included in lease payable on our consolidated balance sheet, and are being amortized over the 20 -year lease term based on the minimum lease payments required under the Leases and our incremental borrowing rate. Future construction costs funded by the Buyer under the 144 Chelmsford Lease will be recognized as additional financing obligations on our consolidated balance sheet as incurred, and will be amortized over the 20 -year lease term based on the minimum lease payments required under the Leases and our incremental borrowing rate when the building is placed into service. As a result of the failed sale-leaseback accounting, we calculated a lease obligation based on the future minimum lease payments discounted at 7.2% as of September 28, 2018 . The discount rate represents the estimated incremental borrowing rate over the lease term of 20 years. The minimum lease payments are recorded as interest expense and in part as a payment of principal reducing the lease obligation. The real property assets in the transaction remain on the consolidated balance sheets and continue to be depreciated over their remaining useful lives. As of September 28, 2018 and September 29, 2017 , approximately $28.3 million and $15.8 million , respectively, of the lease obligation was outstanding associated with the Leases, of which $16.3 million and $3.6 million , respectively, was associated with the 144 Chelmsford Lease that had not yet been placed in service. Additionally, we have capital equipment lease obligations, of which approximately $1.2 million and $2.3 million were outstanding as of September 28, 2018 and September 29, 2017 , respectively. As of September 28, 2018 , future minimum payments under capital lease obligations related to all of our in service Leases were as follows (in thousands): Fiscal year ending: Amount 2019 $ 2,797 2020 2,760 2021 2,686 2022 2,547 2023 2,563 Thereafter 42,247 Total minimum capital lease payments $ 55,600 Less amount representing interest (27,786 ) Present value of net minimum capital lease payments $ 27,814

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 28, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Operating Leases —We have non-cancelable operating lease agreements for office, research and development and manufacturing space in the United States and foreign locations. We also have operating leases for certain equipment and services in the United States and foreign jurisdictions. These lease agreements expire at various dates through 2026 , and certain agreements contain provisions for extension at substantially the same terms as currently in effect. Lease escalation clauses, rent abatements and/or concessions, such as rent holidays and landlord or tenant incentives or allowances, are typically included in the determination of straight-line rent expense over the lease term. Future minimum lease payments for the next five fiscal years as of September 28, 2018 , are as follows (in thousands): 2019 $ 10,068 2020 7,527 2021 5,442 2022 3,766 2023 3,356 Thereafter 4,663 Total minimum lease payments $ 34,822 Rent expense incurred under non-cancelable operating leases was $9.5 million , $10.9 million and $7.0 million in fiscal years 2018 , 2017 and 2016 , respectively. Asset Retirement Obligations —We are obligated under certain facility leases to restore those facilities to the condition in which we or our predecessors first occupied the facilities. We are required to remove leasehold improvements and equipment installed in these facilities prior to termination of the leases. As of the end of fiscal years 2018 , 2017 and 2016 , the estimated costs for the removal of these assets are recorded as asset retirement obligations in other long-term liabilities were $1.8 million , $2.3 million and $4.3 million , respectively. Unused Letter of Credit —As of September 28, 2018 , we had outstanding unused letters of credit from a bank aggregating to $0.4 million . Purchase Commitments —As of September 28, 2018 , we had outstanding non-cancelable purchase commitments aggregating to $ 1.8 million pursuant to inventory supply arrangements. Litigation —From time to time we may be subject to commercial disputes, employment issues, claims by other companies in the industry that we have infringed their intellectual property rights and other similar claims and litigations. Any such claims may lead to future litigation and material damages and defense costs. Other than as set forth below, we were not involved in any material pending legal proceedings during the year ended September 28, 2018 . GaN Lawsuit Against Infineon —On April 26, 2016, we and our wholly-owned subsidiary Nitronex, LLC brought suit against Infineon Technologies Americas Corporation ("Infineon Americas") and Infineon Technologies AG ("Infineon AG" and collectively, with Infineon Americas, "Infineon") in the Federal District Court for the Central District of California, seeking injunctive relief, monetary damages, and specific performance of certain contractual obligations. The suit arose out of agreements relating to GaN-on-Silicon patents that were executed in 2010 by Nitronex Corporation (acquired by us in 2014) and International Rectifier Corporation (acquired by Infineon AG in 2015). We asserted claims for breach of contract, breach of the covenant of good faith and fair dealing, declaratory judgment of contractual rights, declaratory judgment of non-infringement of patents, and, against Infineon AG only, intentional interference with contract and unfair competition, and Infineon Americas asserted contract and patent infringement counterclaims. In an order dated October 31, 2016, the district court granted us a preliminary injunction against Infineon, which then issued on December 7, 2016 and was modified on March 6, 2017. The preliminary injunction declared, among other things, that a licensing agreement between us and Infineon that Infineon had purported to terminate is still in effect. On January 29, 2018, the Federal Circuit affirmed the district court’s decision to enter a preliminary injunction declaring the license agreement to still be in effect, although it reversed other aspects of the district court’s decision. The parties entered into a settlement agreement in October 2018 pursuant to which all claims and counterclaims in the litigation were dismissed by the district court on November 1, 2018 and the patents in dispute were assigned back to MACOM, among other terms.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Sep. 28, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS We established a defined contribution savings plan under Section 401(k) of the Internal Revenue Code of 1986, as amended (Section 401(k)) on October 1, 2009 (401(k) Plan). The 401(k) Plan follows a calendar year, covers substantially all U.S. employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pretax basis, subject to legal limitations. Our contributions to the plan may be made at the discretion of the board of directors. During the fiscal year ended September 28, 2018 , we contributed $2.7 million to our 401(k) Plan for calendar year 2017 . As of September 28, 2018 there were no contributions made by us to the 401 (k) Plan for calendar year 2018 . During the fiscal year ended September 29, 2017 , we contributed $2.4 million to our 401(k) Plan for calendar year 2016 . During the fiscal year ended September 30, 2016 , we contributed $1.9 million to our 401(k) Plan for calendar year 2015 . Our employees located in foreign jurisdictions meeting minimum age and service requirements participate in defined contribution plans whereby participants may defer a portion of their annual compensation on a pretax basis, subject to legal limitations. Company contributions to these plans are discretionary and vary per region. We expensed contributions of $1.2 million , $1.3 million and $1.1 million for fiscal years 2018 , 2017 and 2016 , respectively.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Sep. 28, 2018
Other Liabilities Disclosure [Abstract]
Accrued Liabilities	ACCRUED LIABILITIES Accrued liabilities consist of the following (in thousands): September 28, September 29, Compensation and benefits $ 22,935 $ 32,505 Distribution costs 10,670 5,777 Product warranty 5,756 3,672 Professional fees 1,875 2,140 Rent and utilities 1,660 1,257 Contingent consideration 585 1,679 Income taxes payable 415 4,184 Purchase price holdback 375 1,000 Restructuring costs 89 627 Other 5,585 5,402 Total $ 49,945 $ 58,243

Restructurings

Restructurings	12 Months Ended
	Sep. 28, 2018
Restructuring and Related Activities [Abstract]
Restructurings	RESTRUCTURINGS We have periodically implemented restructuring actions in connection with broader plans to reduce staffing, reduce our internal manufacturing footprint and generally reduce operating costs. The restructuring expenses are primarily comprised of direct and incremental costs related to headcount reductions including severance and outplacement fees for the terminated employees, as well as facility closure costs. During the fiscal quarter ended September 28, 2018, we commenced a plan to exit certain production and product lines including exiting our production facility located in Ithaca, New York. We did not incur any restructuring costs during fiscal year 2018 associated with these plans. We expect to complete these restructuring activities during fiscal year 2019, and incur restructuring costs ranging from approximately $5.3 million and $6.7 million , of which approximately $1.5 million to $1.9 million are one time termination costs, $1.0 million to $1.3 million are contract termination costs and $2.8 million to $3.5 million are asset acceleration expense. Approximately $2.5 million to $3.2 million of these costs are expected to be future cash expenditures. During the fiscal quarter ended December 29, 2017, we initiated plans to restructure our facility in Long Beach, California and to close our facilities in Belfast, the United Kingdom and Sydney, Australia, which represents the majority of our fiscal year 2018 restructuring expenses. As of June 29, 2018, the operations from the Long Beach facility have been consolidated into our other California locations in order to achieve operational synergies. The Belfast and Sydney facilities have been closed as we have discontinued certain product development activities that were performed in those locations. We do not expect to incur any additional restructuring costs associated with these facilities. In fiscal years 2017 and 2016 the restructuring expenses are primarily comprised of direct and incremental costs related to headcount reductions including severance and outplacement fees for the terminated employees. These actions were in connection with broader plans to reduce staffing, reduce our internal manufacturing footprint and, generally, reduce operating costs. The following is a summary of the restructuring charges incurred for the periods presented (in thousands): Fiscal Years 2018 2017 2016 Employee related expenses $ 2,789 $ 2,744 $ 3,465 Facility related expenses 3,476 — — Total restructuring expenses $ 6,265 $ 2,744 $ 3,465 The following is a summary of the costs incurred and remaining balances included in accrued expenses related to restructuring actions taken (in thousands): Fiscal Years 2018 2017 2016 Balance - beginning of year $ 627 $ 3,104 $ 943 Expense 6,265 2,744 3,465 Charges paid/settled (6,803 ) (5,221 ) (1,304 ) Balance - end of year $ 89 $ 627 $ 3,104 The restructuring expenses recorded to date are expected to be paid through the remainder of calendar year 2018 . We expect to incur additional restructuring costs in the range of approximately $5.3 million and $6.7 million during fiscal year 2019 as we complete restructuring actions primarily associated with facility consolidations.

Product Warranties

Product Warranties	12 Months Ended
	Sep. 28, 2018
Guarantees [Abstract]
Product Warranties	PRODUCT WARRANTIES We establish a product warranty liability at the time of revenue recognition. Product warranties generally have terms of 12 months and cover nonconformance with specifications and defects in material or workmanship. For sales to distributors, our warranty generally begins when the product is resold by the distributor. The liability is based on estimated costs to fulfill customer product warranty obligations and utilizes historical product failure rates. Should actual warranty obligations differ from estimates, revisions to the warranty liability may be required. Product warranty liability activity is as follows (in thousands): Fiscal Years 2018 2017 2016 Balance — beginning of year $ 3,672 $ 1,039 $ 656 (Divested)/acquired (49 ) 952 413 Provisions/(expense) 1,865 1,737 (30 ) Direct charges/(payments) 268 (56 ) — Balance — end of year $ 5,756 $ 3,672 $ 1,039

Intangible Assets

Intangible Assets	12 Months Ended
	Sep. 28, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	INTANGIBLE ASSETS Amortization expense related to intangible assets is as follows (in thousands): Fiscal Years 2018 2017 2016 Cost of revenue $ 33,429 $ 30,286 $ 26,615 Selling, general and administrative 48,265 35,456 23,640 Total $ 81,694 $ 65,742 $ 50,255 Intangible assets consist of the following (in thousands): September 28, September 29, Acquired technology $ 251,673 $ 251,655 Customer relationships 518,234 556,648 Trade name 3,400 3,400 Total 773,307 811,703 Less accumulated amortization (260,522 ) (190,611 ) Intangible assets — net $ 512,785 $ 621,092 A summary of the activity in intangible assets and goodwill follows (in thousands): Intangible Assets Total Intangibles Acquired Customer In-Process Research and Development Trade Name Total Goodwill Balance at September 30, 2016 $ 384,471 $ 165,397 $ 207,674 $ 8,000 $ 3,400 $ 120,024 Acquired 436,181 83,518 352,663 — — 195,145 Placed in service — 3,648 — (3,648 ) — — Fair value adjustment — — — — — 220 Currency translation adjustments (4,597 ) (908 ) (3,689 ) — — (1,624 ) Impairments of intangible assets (4,352 ) — — (4,352 ) — — Balance at September 29, 2017 811,703 251,655 556,648 — 3,400 313,765 Allocation to divested business (39,285 ) — (39,285 ) — — (2,560 ) Fair value adjustment — — — — — 2,790 Currency translation adjustments 889 18 871 — — 81 Balance at September 28, 2018 $ 773,307 $ 251,673 $ 518,234 $ — $ 3,400 $ 314,076 As of September 28, 2018 , our estimated amortization of our intangible assets in future fiscal years, was as follows (in thousands): 2019 2020 2021 2022 2023 Thereafter Amortization expense $ 83,749 81,669 74,061 61,830 51,466 156,610 Our trade name is an indefinite-lived intangible asset. During development, in-process research and development (IPR&D) is not subject to amortization and is tested for impairment annually or more frequently if events or changes in circumstances indicate that the asset might be impaired. The impairment test consists of both a qualitative and quantitative assessment using an assumption of ‘more likely than not’ to determine if there were any impairment indicators. If impairment exists, a loss is recognized in an amount equal to that excess. Once an IPR&D project is complete, it becomes a definite long-lived intangible asset and is evaluated for impairment in accordance with our policy for long-lived assets. During the fourth quarter of fiscal year 2017, we completed the last IPR&D project and placed the acquired technology into service. Prior to placing the technology into service we performed an impairment assessment, at which time we determined that the value of the technology was impaired by $4.4 million , which was expensed in the fiscal fourth quarter of 2017. The remaining $3.6 million was placed in service as acquired technology. Accumulated amortization for the acquired technology and customer relationships was $140.0 million and $120.5 million , respectively, as of September 28, 2018 , and $ 106.8 million and $ 83.9 million, respectively, as of September 29, 2017 . During the second quarter of fiscal year 2016, we made a strategic decision to exit the product line and end programs associated with our GaN-on-SiC license and technology transfer to focus on development of our GaN-on-Si efforts. As a result of this strategic decision, we determined that the intangible assets and contractual commitments under the long-term technology licensing and transfer agreement signed in July 2013, as well as certain dedicated fixed assets and inventory, would no longer have any future benefit. The associated charges incurred during the fiscal year 2016 were $ 13.8 million , which included a write-off of $ 10.1 million of intangible assets, $ 0.6 million of property and equipment, $ 1.1 million of contractual commitments and $ 2.0 million of inventory.

Income Taxes

Income Taxes	12 Months Ended
	Sep. 28, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Deferred income taxes reflect the net effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and amounts used for income tax purposes. The components of our deferred tax assets and liabilities are as follows (in thousands): September 28, September 29, Deferred tax assets (liabilities): Federal and foreign net operating losses and credits $ 321,982 $ 396,871 Intangible assets (94,929 ) (180,544 ) Property and equipment (6,293 ) (1,045 ) Other non-current deferred tax assets 13,850 20,756 Deferred compensation 3,810 9,291 Deferred gain 6,575 14,853 Valuation allowance (243,112 ) (274,406 ) Total deferred tax (liability) asset $ 1,883 $ (14,224 ) Included in the above table are the attributes of our Japan jurisdiction which is in a net liability position of $0.1 million and $ 8.8 million relating primarily to intangible assets for fiscal years 2018 and 2017, respectively. As of September 28, 2018 , we had $1,149.2 million of gross federal net operating loss (NOL) carryforwards consisting of $772.7 million relating to the AppliedMicro Acquisition, $158.9 million relating to the Mindspeed Acquisition, $26.2 million relating to the BinOptics Acquisition and $180.8 million relating to losses generated by MACOM. The federal NOL carryforwards will expire at various dates through 2037. The reported net operating loss carryforward includes any limitation under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, which applies to an ownership change as defined under Section 382. During the fourth quarter of fiscal year 2016, we identified and corrected a prior period error where we understated our income tax benefit during 2013 through 2015. This was a result of the incorrect recording of intercompany pretax income among a few of our operating entities and due to the fact that these entities had different statutory tax rates. The out-of-period correction resulted in a $ 3.9 million increase in income tax benefit in the fiscal year ended September 30, 2016 of which $ 1.7 million , $ 1.0 million and $ 1.2 million related to the prior fiscal years 2015, 2014 and 2013, respectively. The domestic and foreign income (loss) from continuing operations before taxes were as follows (in thousands): Fiscal Years 2018 2017 2016 United States $ (145,851 ) $ (111,432 ) $ (46,593 ) Foreign (9,384 ) 61,927 25,022 (Loss) income from operations before income taxes $ (155,235 ) $ (49,505 ) $ (21,571 ) The components of the provision (benefit) for income taxes are as follows (in thousands): Fiscal Years 2018 2017 2016 Current: Federal $ (6,876 ) $ 100 $ (5,861 ) State (160 ) 225 (766 ) Foreign 1,642 7,307 906 Current provision (benefit) (5,394 ) 7,632 (5,721 ) Deferred: Federal 75,428 (42,637 ) (8,163 ) State (15,526 ) (4,037 ) (502 ) Foreign (24,652 ) (466 ) (2,603 ) Change in valuation allowance (51,329 ) 140,419 (994 ) Deferred provision (benefit) (16,079 ) 93,279 (12,262 ) Total provision (benefit) $ (21,473 ) $ 100,911 $ (17,983 ) We recognize deferred tax assets to the extent that we believe that these assets are more likely than not to be realized. In making this determination, we consider available positive and negative evidence and factors that may impact the valuation of our deferred tax asset including results of recent operations, future reversals of existing taxable temporary differences, projected future taxable income, and tax-planning strategies. A significant piece of objective negative evidence evaluated was the cumulative U.S. loss incurred over the three-year period ended September 28, 2018 which we believe limited our ability to consider other subjective evidence, such as our projections for future growth. Certain transaction and integration related expenses incurred in the U.S., associated primarily with the AppliedMicro Acquisition during the three months ended March 31, 2017, resulted for the first time in significant negative objective evidence in the form of adjusted cumulative losses in the U.S. over the past three-year period. This resulted in our determination that there was not sufficient objectively verifiable positive evidence to offset this negative objective evidence and we concluded that a full valuation allowance totaling $93.5 million was required for our U.S. deferred tax assets as of September 29, 2017. In addition, a full valuation allowance was established against the U.S. deferred tax assets acquired in connection with the AppliedMicro Acquisition. The $243.1 million of valuation allowance as of September 28, 2018 relates primarily to federal and state NOLs, tax credit carryforwards and a partial valuation allowance on tax credits in Canada of $13.6 million whose recovery is not considered more likely than not. The $274.4 million of valuation allowance as of September 29, 2017 related primarily to federal and state NOL and tax credit carryforwards assumed in the AppliedMicro Acquisition along with an establishment of a full valuation allowance against the Company’s U.S. deferred tax assets whose recovery is not considered more likely than not. The change during the fiscal year ended September 28, 2018 of $31.3 million primarily relates to the decrease of our deferred tax assets resulting from the lower U.S. federal tax rate, partially offset by a valuation allowance on state NOLs and tax credits in Canada. Our effective tax rates differ from the federal and statutory rate as follows: Fiscal Years 2018 2017 2016 Federal statutory rate 24.5% 35.0% 35.0% Foreign rate differential 5.1 31.9 40.1 State taxes net of federal benefit 0.8 0.2 1.0 Warrant liabilities 4.4 (1.8) (26.7) Change in valuation allowance 34.0 (270.0) 3.0 Research and development credits 9.0 12.8 16.9 Correction of prior period — — 18.3 Provision to return adjustments 8.3 (4.0) 3.5 Nondeductible compensation expense 1.4 (4.1) (9.2) Nondeductible legal fees 0.9 (3.9) (1.8) 2017 tax reform (73.7) — — Other permanent differences (0.9) 0.1 3.3 Effective income tax rate 13.8% (203.8)% 83.4% For fiscal years 2018 , 2017 and 2016 , the effective tax rates to calculate the tax benefit on $155.2 million , $49.5 million and $21.6 million , respectively, of pre-tax loss from continuing operations were 13.8% , (203.8)% and 83.4% , respectively. The effective income tax rate for fiscal years 2018 , 2017 and 2016 were primarily impacted by a lower income tax rate in many foreign jurisdictions in which our foreign subsidiaries operate, research and development tax credits, and fair market value adjustment of warranty liabilities. For fiscal year 2018 and 2017, effective tax rates were also impacted by the valuation allowance. For fiscal year 2018, the effective tax rate was impacted by the Tax Act. For fiscal year 2017, the effective tax rate was impacted by an establishment of a full valuation allowance against our U.S. deferred tax assets. For fiscal year 2016, the effective tax rate impacted by a retroactive enactment of the R&D tax credit from fiscal years 2015. All earnings of foreign subsidiaries are considered indefinitely reinvested for the periods presented. A one-time deemed repatriation of gross foreign earnings and profits totaling $202.0 million will result in approximately $101.5 million in U.S. taxable income for the year ended September 28, 2018 with Grand Cayman and Ireland accounting for $70.0 million and $30.3 million , respectively. Due to the fact that we are in a full U.S. valuation allowance, this one-time deemed repatriation will have no impact on our tax expense. We also expect our current period taxable loss to fully offset this one-time deemed repatriation of taxable income resulting in no additional cash tax payments. Undistributed earnings of all foreign subsidiaries as of September 28, 2018 , subsequent to the one-time deemed repatriation, aggregated $23.6 million , with Ireland and Grand Cayman accounting for $5.1 million and $15.7 million , respectively. It is not practicable to determine the U.S. federal, state and foreign withholding deferred tax liabilities associated with such foreign earnings. Activity related to unrecognized tax benefits is as follows (in thousands): Amount Balance - September 30, 2016 (1,670 ) Additions based on tax positions — Reductions based on tax positions — Balance - September 29, 2017 $ (1,670 ) Additions based on tax positions — Reductions based on tax positions 1,370 Balance at September 28, 2018 $ (300 ) The balance of the unrecognized tax benefit as of September 28, 2018 , is included in other long-term liabilities in the accompanying consolidated balance sheets. The entire balance of unrecognized tax benefits, if recognized, will reduce income tax expense. It is our policy to recognize any interest and penalties accrued related to unrecognized tax benefits in income tax expense. During fiscal year 2018 , we did not make any payment of interest and penalties. There was nothing accrued in the consolidated balance sheets for the payment of interest and penalties at September 28, 2018 , as the remaining unrecognized tax benefits would only serve to reduce our current federal and state NOL carryforwards, if ultimately recognized. A summary of the fiscal tax years that remain subject to examination, as of September 28, 2018 , for the Company’s significant tax jurisdictions are: Jurisdiction Tax Years Subject to Examination United States—federal 2015 - forward United States—various states 2014 - forward Ireland 2016 - forward Generally, we are no longer subject to federal income tax examinations for years before 2015, except to the extent of loss and tax credit carryforwards from those years. On December 22, 2017, the U.S. Congress enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act makes broad and complex changes to the U.S. tax code, including, but not limited to: • reducing the highest marginal U.S. federal corporate income tax rate from 35% in the period ending December 29, 2017 to 21%, effective January 1, 2018; • requiring companies to become liable for a one-time deemed repatriation transition tax (Transition Tax) based on previously untaxed accumulated and current earnings and profits (E&P) of certain foreign subsidiaries for our fiscal year ending September 28, 2018; • generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries that will apply to our fiscal year beginning September 29, 2018; • requiring the inclusion of certain income such as Global Intangible Low Taxed Income (GILTI) earned by controlled foreign corporations (CFCs) in our U.S. federal taxable income that would apply to our fiscal year beginning September 29, 2018; • eliminating the corporate alternative minimum tax (AMT) and changing how existing AMT credits can be realized that will apply to our fiscal year beginning September 29, 2018; • repealing the performance-based compensation exception to the section 162(m) $1.0 million deduction limitation and revising the definition of a covered employee for our fiscal year beginning September 29, 2018; • creating the base erosion anti-abuse tax, a new minimum tax that will apply to our fiscal year beginning September 29, 2018; • creating a new limitation on deductible interest expense that will apply to our fiscal year beginning September 29, 2018; • limiting the degree to which net operating losses can be utilized against taxable income that would apply to losses created beginning with our fiscal year beginning September 29, 2018; • changing rules related to the ability to apply net operating losses against later or earlier tax years that applies to losses created beginning with our fiscal year beginning September 30, 2017; and • an increase in the allowable deduction for costs to acquire qualified property placed into service after September 27, 2017. Our financial results for the fiscal year ended September 28, 2018 includes a non-cash reduction in income tax expense of approximately $2.6 million resulting from the re-measurement of our U.S. deferred tax liabilities to reflect the new 21% U.S. federal tax rate. Due to changes in the net operating loss carryforward rules, we also reduced our deferred tax liability by $5.7 million resulting in a reduction to income tax expense of $5.7 million . To determine the amount of the Transition Tax, we must determine, in addition to other factors, the amount of E&P of the relevant subsidiaries as well as the amount of non-U.S. income taxes paid on such earnings. We were able to make a reasonable estimate of the Transition Tax and have determined that we expect to have sufficient taxable losses during the current year to reduce any cash tax payments associated with the one-time repatriation of E&P down to zero. We are continuing to analyze additional information to more precisely compute the amount of the Transition Tax. The Tax Act creates a new requirement that certain income such as GILTI earned by CFCs must be included in the gross income of the CFCs’ U.S. shareholder. GILTI is the excess of the shareholder's net CFC tested income over the net deemed tangible income return, which is currently defined as the excess of (1) 10 percent of the aggregate of the U.S. shareholder’s pro rata share of the qualified business asset investment of each CFC with respect to which it is a U.S. shareholder over (2) the amount of certain interest expense taken into account in the determination of net CFC-tested income. The Company also assessed whether its valuation allowance analyses are affected by various aspects of the Tax Act (e.g., the Transition Tax, GILTI inclusions and new categories of foreign tax credits). The changes included in the Tax Act are broad and complex. Although we are not able to finalize our evaluation of the impact of the Tax Act at this time due to uncertainties related to any future legislative or regulatory actions related to the Tax Act and availability of information needed to perform the final calculations, we do believe that a full valuation allowance continues to be required. However, we will continue to evaluate the impact the Tax Act may have on our financial statements including the impact on our full valuation allowance against our U.S. deferred tax assets and any impact this would have on our tax expense. The SEC has issued Staff Accounting Bulletin No. 118 that would allow for a measurement period of up to one year after the enactment date of the Tax Act to finalize the application of Accounting Standards Codification Topic 740, Income Taxes. We currently anticipate finalizing and recording any resulting adjustments within one year after the enactment date.

Share - Based Compensation Plan

Share - Based Compensation Plans	12 Months Ended
	Sep. 28, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share - Based Compensation Plans	SHARE-BASED COMPENSATION PLANS Stock Plans We have three equity incentive plans: the Amended and Restated 2009 Omnibus Stock Plan (2009 Plan), the 2012 Omnibus Incentive Plan, as amended (2012 Plan) and the 2012 Employee Stock Purchase Plan, as amended and restated (ESPP). Upon the closing of our initial public offering, all shares that were reserved under the 2009 Plan but not awarded were assumed by the 2012 Plan. No additional awards will be made under the 2009 Plan. Under the 2012 Plan, we have the ability to issue incentive stock options (ISOs), nonqualified stock options (NQs), stock appreciation rights, restricted stock (RSAs), restricted stock units (RSUs), performance-based stock units (PRSUs) and other equity-based awards to employees, directors and outside consultants. The ISOs and NQs must be granted at a price per share not less than the fair value of our common stock on the date of grant. Options granted to date primarily vest based on certain market-based and performance-based criteria as described below. Certain of the share-based awards granted and outstanding as of September 28, 2018 , are subject to accelerated vesting upon a sale of the Company or similar changes in control. Options granted generally have a term of four to seven years. As of September 28, 2018 , we had 14.1 million shares available for future issuance under the 2012 Plan and 3.2 million shares available for issuance under our ESPP. The financial impact of any modifications to share-based awards during the periods presented was not material. Outside of the three equity plans described above, we also grant incentive stock units (ISUs) liability awards to certain of our international employees which typically vest over four years and for which the fair value is determined by our underlying stock price, which are settled in cash upon vesting. As of September 28, 2018 , we had 191,620 ISU awards outstanding with a fair value of $1.9 million recorded as an accrued compensation liability. As of September 29, 2017 , we had 203,293 ISU awards outstanding with a fair value of $4.4 million recorded as an accrued compensation liability. During fiscal year 2018, 68,813 ISU awards were settled with a fair value of $1.4 million . We recorded a gain for these ISU awards of $1.1 million in fiscal year 2018 , primarily as a result of declines in our stock price, and we recorded expense of $3.9 million and $4.0 million in fiscal years 2017 and 2016 , respectively. Share-Based Compensation The following table shows a summary of share-based compensation expense included in the Consolidated Statement of Operations during the periods presented (in thousands): Fiscal Years 2018 2017 2016 Cost of revenue $ 3,869 $ 3,189 $ 2,150 Research and development 13,448 10,565 6,568 Selling, general and administrative 14,620 22,581 18,236 Total $ 31,937 $ 36,335 $ 26,954 Amounts presented above include share-based compensation expense of $0.8 million for fiscal year 2017, which is recorded as discontinued operations related to employees of our Compute business. As of September 28, 2018 , the total unrecognized compensation costs related to outstanding stock options, restricted stock awards and units including awards with time-based and performance-based vesting was $51.3 million , which we expect to recognize over a weighted-average period of 2.4 years . Stock Options A summary of stock option activity for fiscal year 2018 is as follows (in thousands, except per share amounts and contractual term): Number of Shares Weighted-Average Exercise Price per Share Weighted-Average Remaining Contractual Term (in Years) Aggregate Intrinsic Value Options outstanding - September 29, 2017 1,177 $ 31.61 Granted 405 36.58 Exercised (27 ) 2.87 Forfeited, canceled or expired (147 ) 46.29 Options outstanding - September 28, 2018 1,408 $ 32.05 4.93 $ 1,850 Options vested and expected to vest - September 28, 2018 1,408 $ 32.05 4.93 $ 1,850 Options exercisable - September 28, 2018 343 $ 19.08 3.77 $ 1,850 Aggregate intrinsic value represents the difference between our closing stock price on September 28, 2018 , and the exercise price of outstanding, in-the-money options. The total intrinsic value of options exercised was $0.9 million , $8.9 million and $3.7 million for fiscal years 2018 , 2017 and 2016 , respectively. Stock Options with Time-based Vesting Criteria In November 2017, we granted 10,924 incentive stock options and 69,076 non-qualified stock options with a total grant date fair value of $17.55 per share, or $1.4 million . These stock options are valued using a Black-Scholes model, using a volatility rate of 45.7% , a risk-free rate of 2.21% , a strike price of $36.61 and an expected term of 6.5 years . Share-based compensation expense is recognized on a straight-line basis over the service period of approximately 4.5 years . If the required service period is not met for these options, then the share-based compensation expense would be reversed. Stock Options with Performance-based Vesting Criteria We granted approximately 5,000 non-qualified stock options in 2016 with an aggregate fair value of $0.1 million on the date of grant. These stock options will vest and become exercisable if service conditions are met and certain performance criteria are met or exceeded in any period of four consecutive fiscal quarters completed during the term of the options based on pre-established revenue and gross margin targets. We used a Black-Scholes option pricing model to estimate the fair value on the date of grant of $10.54 per option. The fair value of stock options is calculated using valuation assumptions, including volatility, the Company’s stock price, expected term of the option, risk-free interest rate and expected dividends. The stock options have a term of seven years, assuming continued employment with or services to the Company, and have a weighted average exercise price of $ 39.50 and equal to the closing price of the Company’s common stock on the date of grant. The weighted average Black-Scholes input assumptions used for calculating the fair value of these performance-based stock options are as follows: Fiscal Years 2016 Risk-free interest rate 1.15 % Expected term (years) 4.0 Expected volatility 31.8 % Expected dividends — % Stock Options with Market-based Vesting Criteria We grant non-qualified stock options that are subject to vesting only upon the market price of our underlying public stock closing above a certain price target within seven years of the date of grant. Share-based compensation expense is recognized regardless of the number of awards that are earned based on the market condition and is recognized on a straight-line basis over the estimated service period of approximately three years. If the required service period is not met for these options, then the share-based compensation expense would be reversed. In the event that our common stock achieves the target price per share based on a 30 -day trailing average prior to the end of the estimated service period, any remaining unamortized compensation cost will be recognized. Stock options granted for fiscal years 2018 , 2017 and 2016 were 325,000 , 320,000 , and 300,000 , respectively, at weighted average grant date fair values of $15.52 , $13.18 and $11.65 per share, or $5.0 million , $4.3 million and $3.5 million , respectively. These non-qualified stock options with market based vesting conditions were valued using a Monte Carlo simulation model. The weighted average Monte Carlo input assumptions used for calculating the fair value of these market-based stock options are as follows: Fiscal Years 2018 2017 2016 Risk-free interest rate 2.3 % 1.9 % 2.1 % Expected term (years) 3.4 7.0 7.0 Expected volatility 45.8 % 32.3 % 36.5 % Target price $98.99 $67.39 $64.22 Restricted Stock Awards and Units A summary of restricted stock awards and units activity for fiscal year 2018 is as follows (in thousands): Number of Shares Weighted-Average Grant Date Fair Value Aggregate Intrinsic Value Issued and unvested - September 29, 2017 1,907 $ 39.20 $ 85,093 Granted 1,145 26.68 Vested (906 ) 35.24 Forfeited, canceled or expired (274 ) 34.56 Issued and unvested shares - September 28, 2018 1,872 34.15 $ 38,452 As of September 28, 2018 , the aggregate intrinsic value of vested and expected to vest restricted stock units including time-based and performance-based units was $37.1 million for fiscal year 2018 . The total fair value of restricted stock awards and units vested was $19.7 million , $51.2 million and $26.5 million for the fiscal years 2018 , 2017 and 2016 , respectively. In addition to RSUs, we also issue PRSUs with specific performance vesting criteria. These PRSUs have both a service and performance-based vesting condition and awards are divided into three equal tranches and vest based on achieving certain adjusted earnings per share growth metrics. The service condition requires participants to be employed on May 15th of the following year once the performance condition has been met. Depending on the actual performance achieved, a participant may earn between 0% to 300% of the targeted shares for each tranche, which is determined based on a straight-line interpolation applied for the achievement between the specified performance ranges. As of September 28, 2018 , no performance condition targets had been met for awards with future service conditions. We granted 84,753 PRSUs during fiscal year 2018 . The amount of incremental PRSU awards that could ultimately vest if all performance criteria are achieved would be 413,916 shares assuming a maximum of 300% of the targeted shares. Employee Stock Purchase Plan The ESPP allows eligible employees to purchase shares of our common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. In administering the ESPP, the board of directors has limited discretion to set the length of the offering periods thereunder. As of September 28, 2018 , total unrecognized compensation cost related to the ESPP was not material. In fiscal years 2018 , 2017 and 2016 , 305,851 , 146,149 and 154,187 , respectively, of shares of common stock were issued under the ESPP. The 2012 Plan contains an “evergreen” provision, pursuant to which the number of shares of common stock available for issuance under the 2012 Plan can be increased on the first day of each fiscal year by the lesser of (a) 4.0% of outstanding common stock on a fully diluted basis as of the end of the immediately preceding fiscal year, (b) 1.9 million shares of common stock and (c) a lesser amount determined by the board of directors; provided, however, that any shares from any increases in previous years that are not actually issued will continue to be available for issuance under the 2012 Plan. The ESPP also contains an “evergreen” provision, pursuant to which the number of shares of common stock available for issuance under the ESPP can be increased on the first day of each fiscal year by the lesser of (a) 1.25% of outstanding common stock on a fully diluted basis as of the end of the immediately preceding fiscal year, (b) 550,000 shares of common stock and (c) a lesser amount determined by the board of directors; provided, however, that any shares from any increases in previous years that are not actually issued will continue to be available for issuance under the ESPP. In fiscal year 2018 , pursuant to the evergreen provisions, the number of shares of common stock available for issuance under the 2012 Plan and the ESPP were increased by 1.9 million shares and 550,000 shares, respectively.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Sep. 28, 2018
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY We have authorized 10 million shares of $0.001 par value preferred stock and 300 million shares of $0.001 par value common stock as of September 28, 2018 and September 29, 2017 . The outstanding shares of common stock as of September 28, 2018 and September 29, 2017 , presented in the accompanying consolidated statements of stockholders’ equity, exclude 6,100 and 200 unvested shares of restricted stock awards, respectively, issued as compensation to employees that were subject to forfeiture. Common Stock Warrants —In March 2012, we issued warrants to purchase 1,281,358 shares of common stock for $14.05 per share. The warrants expire December 21, 2020 , or earlier as per the terms of the agreement, including immediately following consummation of a sale of all or substantially all assets or capital stock or other equity securities, including by merger, consolidation, recapitalization or similar transactions. We do not currently have sufficient registered and available shares to immediately satisfy a request for registration, if such a request were made. As of September 28, 2018 , no exercise of the warrants had occurred and no request had been made to register the warrants or any underlying securities for resale by the holders. We are recording the estimated fair values of the warrants as a long-term liability in the accompanying consolidated financial statements with changes in the estimated fair value being recorded in the accompanying statements of operations.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Sep. 28, 2018
Related Party Transactions [Abstract]
Related-Party Transactions	RELATED-PARTY TRANSACTIONS Cadence Design Systems, Inc. (Cadence) provides us with certain engineering licenses on an ongoing basis. Geoffrey Ribar, who joined our board of directors on March 22, 2017, served as an officer of Cadence through September 30, 2017 and served as a Senior Advisor to Cadence until March 31, 2018. During fiscal year 2018, we made payments of $4.1 million to Cadence prior to March 31, 2018. During fiscal year 2017, we made payments of $6.3 million subsequent to Mr. Ribar joining our board of directors.

Discontinued Operations

Discontinued Operations	12 Months Ended
	Sep. 28, 2018
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	DISCONTINUED OPERATIONS Divested Business On May 10, 2018, we completed the sale and transfer of certain assets associated with our Japan-based long-range optical subassembly business (the LR4 business), pursuant to an Asset Purchase and Intellectual Property License Agreement, dated April 30, 2018 (the LR4 Agreement). The LR4 Agreement provided that the buyer would pay us $5.0 million within 30 days following the closing of the transactions contemplated by the LR4 Agreement, provide us with the opportunity to supply components, and would pay us further amounts to be determined for inventory and fixed assets within 60 days of receipt of required government approvals. As of September 28, 2018, we have received $5.0 million of consideration and expect additional consideration before the end of calendar 2018 of $12.2 million , net of tax, of which $7.4 million has been recorded as other current assets and $4.8 million has been recorded as assets held for sale as they had not been transferred to the buyer as of September 28, 2018. As a result of the transaction, during fiscal year 2018 we recorded a loss on disposal of $34.3 million associated with LR4 business as other expense, comprised of expected proceeds of $17.2 million , subject to receipt of required government approvals, less the carrying value of assets sold, primarily including customer relationship intangible assets of $27.7 million , inventory of $13.7 million , fixed assets of $7.6 million and goodwill of $2.6 million . The transaction did not meet the criteria of discontinued operations. We also entered into a Transition Services Agreement (the LR4 TSA) with the buyer, pursuant to which we agreed to incur up to $2.0 million of operating expenses for certain ongoing administrative services to support the buyer for up to six months after the closing of the transaction. During fiscal year 2018, we have incurred $2.0 million of expenses associated with the LR4 TSA which were recorded as general and administrative expenses. Discontinued Operations On October 27, 2017, we entered into a purchase agreement to sell the Compute business. In consideration for the transfer and sale of the Compute business, we received an equity interest in the buyer valued at approximately $36.5 million , representing the carrying value of the assets divested and representing less than 20.0% of the buyer's total outstanding equity. The operations of the Compute business were accounted for as discontinued operations through the date of divestiture. We also entered into a transition services agreement (the Compute TSA), pursuant to which we agreed to perform certain primarily general and administrative functions on the buyer's behalf during a migration period and for which we are reimbursed for costs incurred. During the fiscal year 2018 , we received $3.6 million of reimbursements under the Compute TSA, which was recorded as a reduction of our general and administrative expenses. In August of fiscal year 2015, we sold our Automotive business, as the Automotive business was not consistent with our long-term strategic vision from both a growth and profitability perspective. Additionally, we entered into a Consulting Agreement with the buyer pursuant to which we were to provide the buyer with certain non-design advisory services for a period of two years following the closing of the transaction for up to $15.0 million , from which we have recorded $7.5 million as other income during both fiscal years 2017 and 2016. No income was recognized during fiscal year 2018. During fiscal year 2017, we received $18.0 million , the full amount of the indemnification escrow. The accompanying consolidated statement of operations includes the following operating results related to these discontinued operations (in thousands): Fiscal Years 2018 2017 2016 Revenue (1) $ — $ 660 $ — Cost of revenue (1) (596 ) 2,252 — Gross (loss) profit 596 (1,592 ) — Operating expenses: Research and development (1) 5,251 29,167 — Selling, general and administrative (1) 1,560 13,840 — Total operating expenses 6,811 43,007 — (Loss) income from discontinued operations (1) (6,215 ) (44,599 ) — Other income (2) — 7,500 7,500 Gain on sale (2) — 18,022 308 (Loss) income before income taxes (6,215 ) (19,077 ) 7,808 Income tax provision (benefit) — — 2,786 (Loss) income from discontinued operations (6,215 ) (19,077 ) 5,022 Cash flow from Operating Activities (1) (10,734 ) (42,776 ) — Cash flow from Investing Activities (2) — 25,522 7,500 (1) Amounts are associated with the Compute business. (2) Amounts are associated with the Automotive business. For the fiscal year ended September 29, 2017, we recorded assets held for sale of $35.6 million , which included inventory and other assets of $1.3 million , property and equipment of $7.8 million , goodwill and intangibles of $28.4 million , as well as a $2.0 million provision for disposition costs. During the same period, liabilities held for sale amounted to $2.1 million .

Earnings Per Share

Earnings Per Share	12 Months Ended
	Sep. 28, 2018
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE The following table set forth the computation for basic and diluted net income (loss) per share of common stock (in thousands, except per share data): Fiscal Years 2018 2017 2016 Numerator: Loss from continuing operations $ (133,762 ) $ (150,416 ) $ (3,588 ) (Loss) income from discontinued operations (6,215 ) (19,077 ) 5,022 Net (loss) income (139,977 ) (169,493 ) 1,434 Warrant liability gain (27,646 ) — — Net (loss) income attributable to common stockholders $ (167,623 ) $ (169,493 ) $ 1,434 Denominator: Weighted average common shares outstanding-basic 64,741 60,704 53,364 Dilutive effect of warrants 570 — — Weighted average common shares outstanding-diluted 65,311 60,704 53,364 Common stock earnings per share-basic: Continuing operations $ (2.07 ) $ (2.48 ) $ (0.07 ) Discontinued operations (0.10 ) (0.31 ) 0.09 Net common stock earnings per share-basic $ (2.16 ) $ (2.79 ) $ 0.03 Common stock earnings per share-diluted: Continuing operations $ (2.47 ) $ (2.48 ) $ (0.07 ) Discontinued operations (0.10 ) (0.31 ) 0.09 Net common stock earnings per share-diluted $ (2.57 ) $ (2.79 ) $ 0.03 As of September 28, 2018 , we had warrants outstanding which were reported as a liability on the consolidated balance sheet. During fiscal year 2018 , we recorded a $27.6 million gain associated with adjusting the fair value of the warrants, in the consolidated statements of operations primarily as a result of declines in our stock price. When calculating earnings per share we are required to adjust for the dilutive effect of outstanding common stock equivalents, including adjustment to the numerator for the dilutive effect of contracts that must be settled in common stock. During the fiscal year ended September 28, 2018 , we adjusted the numerator to exclude the warrant gain of $27.6 million and the denominator by the incremental shares of 569,667 under the treasury stock method. For the fiscal year 2018 , the table above excludes the effects of 375,940 shares of potential shares of common stock issuable upon exercise of stock options, restricted stock and restricted stock units as the inclusion would be antidilutive. The table also excludes the effects of 1,877,401 and 1,855,049 shares for fiscal years 2017 and 2016 , respectively, of potential shares of common stock issuable upon exercise of stock options, restricted stock, restricted stock units and warrants as the inclusion would be antidilutive.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Sep. 28, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	SUPPLEMENTAL CASH FLOW INFORMATION As of September 28, 2018 and September 29, 2017 , we had $4.0 million and $ 7.6 million , respectively, in unpaid amounts related to purchases of property and equipment included in accounts payable and accrued liabilities. These amounts have been excluded from the payments for purchases of property and equipment in the accompanying consolidated statements of cash flows until paid. In January 2017, we issued common stock with a fair value of $465.1 million in connection with the AppliedMicro Acquisition. This was accounted for as a non-cash transaction as no shares were purchased or sold as part of the transaction. During fiscal years 2018 and 2017 , we capitalized $18.4 million and $3.6 million , respectively, of net construction costs relating to the 144 Chelmsford Street facility, of which $12.7 million and $3.6 million , respectively, were accounted for as a non-cash transaction as the costs were paid by the developer. During fiscal year 2018, we divested the Compute business with net assets valued at approximately $36.5 million in exchange for a $36.5 million equity interest in Compute. During fiscal year 2018 , we recorded $10.4 million of losses associated with this investment based on our proportionate share of the losses of Compute. The following is supplemental cash flow information regarding non-cash investing and financing activities (in thousands): Fiscal Years 2018 2017 2016 Cash paid for interest $ 29,698 $ 30,529 $ 16,335 Cash paid (refunded) for income taxes $ 3,559 $ (3,161 ) $ (373 )

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Sep. 28, 2018
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The components of accumulated other comprehensive income (loss), net of income taxes, are as follows: Foreign Currency Items Other Items Total Balance - September 30, 2016 $ 9,138 $ (99 ) $ 9,039 Foreign currency translation, net of tax (5,999 ) — (5,999 ) Unrealized gain/loss on short-term investments, net of tax — (63 ) (63 ) Balance - September 29, 2017 3,139 (162 ) 2,977 Foreign currency translation, net of tax (502 ) — (502 ) Unrealized gain/loss on short-term investments, net of tax — (287 ) (287 ) Balance at September 28, 2018 $ 2,637 $ (449 ) $ 2,188

Geographic and Significant Cust

Geographic and Significant Customer Information	12 Months Ended
	Sep. 28, 2018
Segment Reporting [Abstract]
Geographic and Significant Customer Information	GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION We have one reportable operating segment that designs, develops, manufactures and markets semiconductors and modules. The determination of the number of reportable operating segments is based on the chief operating decision maker’s use of financial information for the purposes of assessing performance and making operating decisions. In evaluating financial performance and making operating decisions, the chief operating decision maker primarily uses consolidated revenue, gross profit and operating income (loss). Information about our operations in different geographic regions, based upon customer locations, is presented below (in thousands): Fiscal Years Revenue by Geographic Region 2018 2017 2016 United States $ 272,951 $ 265,038 $ 155,998 China 159,763 206,136 201,911 Asia Pacific, excluding China (1) 79,581 170,826 144,872 Other Countries (2) 58,103 56,772 41,557 Total $ 570,398 $ 698,772 $ 544,338 (1) Asia Pacific represents Taiwan, Japan, Singapore, India, Thailand, South Korea, Australia, Malaysia, New Zealand, the Philippines and Vietnam. (2) No international country or region represented greater than 10% of the total revenue as of the dates presented, other than China and the Asia-Pacific region as presented above. As of September 28, September 29, Long-Lived Assets by Geographic Region United States $ 122,888 $ 101,044 Asia Pacific (1) 24,702 24,945 Other Countries (2) 2,333 5,030 Total $ 149,923 $ 131,019 (1) Asia Pacific represents Taiwan, Japan, Singapore, India, Thailand, South Korea, Malaysia, the Philippines, Vietnam and China. (2) No international country or region represented greater than 10% of the total net long-lived assets as of the dates presented, other than the Asia-Pacific region as presented above. The following is a summary of customer concentrations as a percentage of total sales and accounts receivable as of and for the periods presented: Fiscal Years Revenue 2018 2017 2016 Customer A 13 % 11 % 11 % Customer B 6 % 10 % 15 % Customer C 2 % 6 % 12 % September 28, September 29, Accounts Receivable Customer A 19 % 13 % Customer D 26 % 14 % No other customer represented more than 10% of revenue or accounts receivable in the periods presented in the accompanying consolidated financial statements. In fiscal years 2018 , 2017 and 2016 , our top ten customers represented an aggregate of 57% , 52% and 62% of total revenue, respectively.

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Sep. 28, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	QUARTERLY FINANCIAL DATA (UNAUDITED) (In thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Fiscal Year Fiscal Year 2018 Revenue $ 130,925 $ 150,414 $ 137,872 $ 151,187 $ 570,398 Gross profit 60,954 65,601 48,169 70,982 245,706 Loss from continuing operations (16,970 ) (15,466 ) (85,210 ) (16,116 ) (133,762 ) Loss from discontinued operations (1) (5,599 ) (18 ) (220 ) (378 ) (6,215 ) Per share data (2) Loss from continuing operations, basic $ (0.26 ) $ (0.24 ) $ (1.31 ) $ (0.25 ) $ (2.07 ) Loss from discontinued operations, basic $ (0.09 ) $ 0.00 $ 0.00 $ (0.01 ) $ (0.10 ) Per share data (2) (3) Loss from continuing operations, diluted $ (0.49 ) $ (0.50 ) $ (1.31 ) $ (0.29 ) $ (2.47 ) Loss from discontinued operations, diluted $ (0.09 ) $ 0.00 $ 0.00 $ (0.01 ) $ (0.10 ) Fiscal Year 2017 Revenue $ 151,752 $ 186,084 $ 194,555 $ 166,381 $ 698,772 Gross profit 78,495 68,864 92,629 86,896 326,884 Loss from continuing operations (2,171 ) (134,267 ) (13,977 ) (1 ) (150,416 ) Income (loss) from discontinued operations (1) 1,206 4,136 (13,700 ) (10,719 ) (19,077 ) Per share data (2) Loss from continuing operations, basic $ (0.04 ) $ (2.21 ) $ (0.22 ) $ 0.00 $ (2.48 ) Income (loss) from discontinued operations, basic $ 0.02 $ 0.07 $ (0.21 ) $ (0.17 ) $ (0.31 ) Per share data (2) (3) Loss from continuing operations, diluted $ (0.04 ) $ (2.21 ) $ (0.22 ) $ (0.21 ) $ (2.48 ) Income (loss) from discontinued operations, diluted $ 0.02 $ 0.07 $ (0.21 ) $ (0.16 ) $ (0.31 ) ____________ (1) During the second quarter of fiscal year 2017, we announced a plan to divest the Compute business of AppliedMicro, and have included the results of the Compute business as discontinued operations in each subsequent quarter. (2) Earnings per share calculations for each of the quarters are based on the weighted average number of shares outstanding and included common stock equivalents in each period. Therefore, the sums of the quarters do not necessarily equal the full year earnings per share. (3) Diluted (loss) income per share for the fiscal first, second and fourth quarters of 2018 and the fiscal fourth quarter 2017 excluded $14.6 million , $17.0 million , $2.8 million and $14.0 million , respectively, related to warrant liability gain.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Sep. 28, 2018
Accounting Policies [Abstract]
Principles of Consolidation, Basis of Presentation and Reclassification	Principles of Consolidation, Basis of Presentation and Reclassification —We have one reportable segment, semiconductors and modules. The accompanying consolidated financial statements include our accounts and the accounts of our majority-owned subsidiaries. Certain prior period financial statement amounts, such as deferred revenue and cash flow line item presentation have been adjusted to conform to currently reported presentations . All intercompany balances and transactions have been eliminated in consolidation. We have a 52- or 53-week fiscal year ending on the Friday closest to the last day of September. The fiscal years 2018 , 2017 and 2016 included 52 weeks. To offset the effect of holidays, for fiscal years in which there are 53 weeks, we typically include the extra week arising in our fiscal years in the first quarter.
Use of Estimates	Use of Estimates —The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the U.S. requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities during the reporting periods, the reported amounts of revenue and expenses during the reporting periods and the disclosure of contingent assets and liabilities at the date of the financial statements. On an ongoing basis, we base estimates and assumptions on historical experience, currently available information and various other factors that management believes to be reasonable under the circumstances. Actual results may differ from these estimates and assumptions.
Discontinued Operations	Discontinued Operations— In the first quarter of fiscal year 2018, we divested AppliedMicro's compute business (the Compute business). In the third quarter of fiscal year 2018, we divested our Japan-based long-range optical subassembly business (the LR4 business). The operating results of the LR4 business have been reflected in our continuing operations up through the May 10, 2018 sale date with the $34.3 million loss on disposal recorded as other expense. The operating results of the Compute business are reflected in discontinued operations.
Foreign Currency Translation and Remeasurement	Foreign Currency Translation and Remeasurement —Our consolidated financial statements are presented in U.S. dollars. While the majority of our foreign operations use the U.S. dollar as the functional currency, the financial statements of our foreign operations for which the functional currency is not the U.S. dollar are translated into U.S. dollars at the exchange rates in effect at the balance sheet dates (for assets and liabilities) and at average exchange rates (for revenue and expenses). The unrealized translation gains and losses on the net investment in these foreign operations are accumulated as a component of other comprehensive (loss) income. The financial statements of our foreign operations where the functional currency is the U.S. dollar, but where the underlying transactions are transacted in a different currency, are remeasured at the exchange rate in effect at the balance sheet date with respect to monetary assets and liabilities. Nonmonetary assets and liabilities, such as inventories and property and equipment and related statements of operations accounts, such as cost of revenue and depreciation, are remeasured at historical exchange rates. Revenue and expenses, other than cost of revenue, amortization and depreciation, are translated at the average exchange rate for the period in which the transaction occurred. The net gains and losses on foreign currency remeasurement are reflected in selling, general and administrative expense in the accompanying consolidated statements of operations. Net foreign exchange transaction gains and losses for all periods presented were not material.
Cash and Cash Equivalents	Cash and Cash Equivalents —Cash equivalents are primarily composed of short-term, highly-liquid instruments with an original maturity of three months or less and consist primarily of money market funds.
Investments	Investments — Short-term investments: We classify our short-term investments as available-for-sale. Our investments classified as available-for-sale are recorded at fair value based upon third party pricing at period end. Unrealized gains and losses that are deemed temporary in nature are recorded in accumulated other comprehensive income and loss as a separate component of stockholders’ equity. A decline in the fair value of any security below cost that is deemed other than temporary results in a charge to earnings and the corresponding establishment of a new cost basis for the security. Premiums and discounts are amortized (accreted) over the life of the related security as an adjustment to its yield. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of investments sold.
Inventories	Inventories —Inventories are stated at the lower of cost or net realizable value. We use a combination of standard cost and moving weighted-average cost methodologies to determine the cost basis for our inventories, approximating a first-in, first-out basis. The standard cost of finished goods and work-in-process inventory is composed of material, labor and manufacturing overhead, which approximates actual cost. In addition to stating inventory at the lower of cost or net realizable value, we also evaluate inventory each reporting period for excess quantities and obsolescence, establishing reserves when necessary based upon historical experience, assessment of economic conditions and expected demand. Once recorded, these reserves are considered permanent adjustments to the carrying value of inventory.
Property and Equipment	Property and Equipment —Property and equipment are stated at cost, less accumulated depreciation and amortization. Expenditures for maintenance and repairs are charged to expense as incurred, whereas major improvements that significantly extend the useful life of the assets are capitalized as additions to property and equipment. Property and equipment are depreciated or amortized using the straight-line method over the following estimated useful lives: Asset Classification Estimated Useful Life In Years Buildings and improvements 20 – 40 Capital lease assets 5 - 20 Machinery and equipment 2 – 7 Computer equipment and software 2 – 5 Furniture and fixtures 7 – 10 Leasehold improvements Shorter of useful life or term of lease
Goodwill and Indefinite-lived Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets —We have goodwill and certain intangible assets with indefinite lives which are not subject to amortization; these are reviewed for impairment annually as of the end of our August fiscal month end and more frequently if events or changes in circumstances indicate that the assets may be impaired. For our assessment of goodwill impairment, we compare the carrying value of the reporting unit to the fair value of the Company. For our assessment of in-service indefinite-lived assets we compare the carrying value of the asset to the estimated fair value of the asset. For indefinite-lived assets not in service, such as in-process research and development, we perform both qualitative and quantitative assessments using an assumption of "more likely than not" to determine if there are any impairment indicators. If impairment exists, a loss is recorded to write down the value of the assets to their implied fair values. During the fiscal year ended September 29, 2017, we recorded impairment charges of $4.4 million related to indefinite-lived intangible assets. S ee Note 16 - Intangible Assets , for further detail of these impairment charges.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets —Long-lived assets include property and equipment and definite-lived intangible assets subject to amortization. We evaluate long-lived assets for recoverability when events or changes in circumstances indicate that their carrying amounts may not be recoverable. Circumstances which could trigger a review include, but are not limited to, significant decreases in the market price of the asset or asset group, significant adverse changes in the business climate or legal factors, the accumulation of costs significantly in excess of the amount originally expected for the acquisition or construction of the asset, current period cash flow or operating losses combined with a history of losses or a forecast of continuing losses associated with the use of the asset and a current expectation that the asset will more likely than not, be sold or disposed of significantly before the end of its previously estimated useful life. In evaluating a long-lived asset for recoverability, we estimate the undiscounted cash flows expected to result from our use and eventual disposition of the asset. If the sum of the expected undiscounted cash flows is less than the carrying amount of the asset, an impairment loss, equal to the excess of the carrying amount over the fair value of the asset, is recognized. In fiscal year 2018, we recorded impairment charges of $6.6 million , including $4.6 million related to property and equipment and $2.0 million related to other assets designated for future use with Zhongxing Telecommunications Equipment Corporation (ZTE), as a result of the Bureau of Industry and Security (BIS) denial order on April 15, 2018. In fiscal year 2016 we recorded impairment charges of $ 13.8 million related to our strategic decision to exit a product line and end programs associated with our GaN-on Silicon Carbide (GaN-on-SiC) license and technology transfer. There were no impairments of long-lived assets in fiscal year 2017. Intangible assets related to in-process research and development acquired are not amortized until the underlying asset begins revenue-generating activity, at which time it is amortized over its estimated useful life. Intangibles related to abandoned in-process research and development projects are expensed in the period the project is abandoned.
Other Intangible Assets	Other Intangible Assets —Our other intangible assets, including acquired technology and customer relationships, are definite-lived assets and are subject to amortization. We amortize definite-lived assets over their estimated useful lives, which range from five to fourteen years, generally based on the pattern over which we expect to receive the economic benefit from these assets.
Revenue Recognition	Revenue Recognition —We recognize revenue when: (i) persuasive evidence of an arrangement exists; (ii) delivery or services have been rendered; (iii) the price is fixed or determinable; and (iv) collectability is reasonably assured. We recognize revenue with the transfer of title and risk of loss and provide for reserves for returns and other allowances. We generally do not provide customers other than distributors the right to return product, with the exception of warranty related matters. Shipping and handling fees billed to customers are recorded as revenue while the related costs are classified as a component cost of revenue. We provide warranties for certain products and accrue the estimated costs of warranty claims in the period the related revenue is recorded. Product warranties generally have terms of 12 months and cover nonconformance with specifications and defects in material or workmanship. For sales to distributors, our warranty generally begins when the product is resold by the distributor. The liability is based on estimated costs to fulfill customer product warranty obligations and utilizes historical product failure rates. Should actual warranty obligations differ from estimates, revisions to the warranty liability may be required. We have agreements with some distribution customers for various programs, including compensation, volume-based pricing, obsolete inventory, new products and stock rotation. Sales to these distribution customers, as well as the existence of compensation programs, are in accordance with terms set forth in written agreements with these distribution customers. In general, credits allowed under these programs are capped based upon individual distributor agreements. We record charges associated with these programs as a reduction of revenue at the time of sale with a corresponding adjustment to accounts receivable based upon historical activity. Our policy is to use a 12 months rolling historical experience rate and an estimated general reserve percentage in order to estimate the necessary allowance to be recorded.
Research and Development Costs	Research and Development Costs —Costs incurred in the research and development of products are expensed as incurred.
Income Taxes	Income Taxes —
Earnings Per Share	Earnings Per Share —Basic net (loss) income per share is computed by dividing net (loss) income by the weighted-average number of common shares outstanding during the period, excluding the dilutive effect of common stock equivalents. Diluted net (loss) income per share reflects the dilutive effect of common stock equivalents, such as stock options, warrants and restricted stock units, using the treasury stock method.
Fair Value Measurements	Fair Value Measurements —Financial assets and liabilities are measured at fair value. Fair value is an exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability at the measurement date under current market conditions in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, we group financial assets and liabilities in a three-tier fair value hierarchy, according to the inputs used in measuring fair value as follows: Level 1—observable inputs such as quoted prices in active markets for identical assets and liabilities; Level 2—inputs other than quoted prices in active markets that are observable either directly or indirectly, such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical assets and liabilities in markets that are not active and model-based valuation techniques for which significant assumptions are observable in active markets; and, Level 3—unobservable inputs for which there is little or no market data, requiring us to develop our own assumptions for model-based valuation techniques. This hierarchy requires us to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. Money market funds are actively traded and consist of highly liquid investments with original maturities of 90 days or less. They are measured at their net asset value and classified as Level 1. Corporate and agency bonds and commercial paper are categorized as Level 2 assets except where sufficient quoted prices exist in active markets, in which case such securities are categorized as Level 1 assets. These securities are valued using third-party pricing services. These services may use, for example, model-based pricing methods that utilize observable market data as inputs. We generally use quoted prices for recent trading activity of assets with similar characteristics to the debt security or bond being valued. The securities and bonds priced using such methods are generally classified as Level 2. Broker dealer bids or quotes on securities with similar characteristics may also be used. The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to the short-term nature of these assets and liabilities.
Contingent Consideration	Contingent Consideration —We estimate and record at the acquisition date, the fair value of contingent consideration making up part of the purchase price consideration for acquisitions. Additionally, at each reporting period, we estimate the change in the fair value of contingent consideration and any change in fair value is recognized in the consolidated statements of operations. We estimate the fair value of contingent consideration by discounting the associated expected cash flows, using a probability-weighted, discounted cash flow model. The estimate of the fair value of contingent consideration requires subjective assumptions to be made regarding future operating results, discount rates and probabilities assigned to various potential operating result scenarios.
Share-Based Compensation	Share-Based Compensation —We account for all share-based compensation arrangements using the fair value method. We recognize compensation expense over the requisite service period of the award, which is generally the vesting period, using the straight-line method for service-based awards and the accelerated method for performance-based awards, and providing that the minimum amount of compensation recorded is equal to the vested portion of the award. We record the expense in the consolidated statements of operations in the same manner in which the award recipients’ salary costs are classified. For restricted stock awards with service conditions we use the closing stock price on the date of grant to estimate the fair value of the awards. We use the Black-Scholes option-pricing model to estimate the fair value of stock options with service and performance conditions, inclusive of assumptions for risk-free interest rates, dividends, expected terms and estimated volatility. We use the Monte Carlo Simulation analysis to estimate the fair value of stock options with market conditions, inclusive of assumptions for risk free interest rates, expected term, expected volatility and the target price. We derive the risk-free interest rate assumption from the U.S. Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to the expected term of the award being valued. We base the assumed dividend yield on its expectation of not paying dividends in the foreseeable future. We calculate the weighted-average expected term of the options using the simplified method, which is a method of applying a formula that uses the vesting term and the contractual term to compute the expected term of a stock option. The decision to use the simplified method is based on a lack of relevant historical data, due to our limited operating experience. In addition, we calculate our estimated volatility using our historical stock price volatility data. In fiscal year 2018 we adopted Accounting Standards Update (ASU) 2016-09, Compensation - Stock Compensation (ASU 2016-09), and upon adoption we elected to account for forfeitures when they occur. Prior to the adoption of ASU 2016-09 the accounting for share-based compensation required forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differed from those estimates. See the Recent Accounting Pronouncements section below for additional detail on the adoption of ASU 2016-09. Share-based awards that are settled in cash are recorded as liabilities. The measurement of the liability and compensation cost for these awards is based on the fair value of the award, and is recorded in operating income over the award’s vesting period. Changes in our payment obligation prior to the settlement date of a stock-based award are recorded as compensation expense in operating income in the period of the change. The final payment amount for such awards is established on the date of the exercise of the award by the employee.
Guarantees and Indemnification Obligations	Guarantees and Indemnification Obligations —We enter into agreements in the ordinary course of business with, among others, customers, distributors and original equipment manufacturers (OEM). Most of these agreements require us to indemnify the other party against third-party claims alleging that a Company product infringes a patent and/or copyright. Certain agreements in which we grant limited licenses to Company intellectual property require us to indemnify the other party against third-party claims alleging that the use of the licensed intellectual property infringes a third-party's intellectual property. Certain of these agreements require us to indemnify the other party against certain claims relating to property damage, personal injury or the acts or omissions, its employees, agents or representatives. In addition, from time to time, we have made certain guarantees in the form of warranties regarding the performance of Company products to customers. We have agreements with certain vendors, creditors, lessors and service providers pursuant to which we have agreed to indemnify the other party for specified matters, such as acts and omissions, its employees, agents or representatives. We have procurement or license agreements with respect to technology used in our products and agreements in which we obtain rights to a product from an OEM. Under some of these agreements, we have agreed to indemnify the supplier for certain claims that may be brought against such party with respect to our acts or omissions relating to the supplied products or technologies. Our certificate of incorporation and agreements with certain of our directors and officers and certain of our subsidiaries’ directors and officers provide them indemnification rights, to the extent legally permissible, against liabilities incurred by them in connection with legal actions in which they may become involved by reason of their service as a director or officer. As a matter of practice, we have maintained director and officer liability insurance coverage, including coverage for directors and officers of acquired companies. We have not experienced any losses related to these indemnification obligations in any period presented and no claims with respect thereto were outstanding as of September 28, 2018 and September 29, 2017 . We do not expect significant claims related to these indemnification obligations and, consequently, have concluded that the fair value of these obligations is negligible. No liabilities related to indemnification liabilities have been established.
Recent Accounting Pronouncements	Recent Accounting Pronouncements — Pronouncements Adopted in Fiscal Year 2018 In March 2016, the Financial Accounting Standards Board (FASB) issued ASU 2016-09, which simplifies several aspects of the accounting for employee share-based payment transactions for both public and nonpublic entities. We adopted this ASU as of September 30, 2017. Prior to ASU 2016-09, the accounting for share-based compensation required forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. ASU 2016-09 allows an entity to make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest or account for forfeitures when they occur. ASU 2016-09 requires an entity that elects to account for forfeitures when they occur to apply the accounting change on a modified retrospective basis as a cumulative-effect adjustment to retained earnings as of the date of adoption. We elected to account for forfeitures when they occur, and recorded a $1.0 million cumulative-effect adjustment to beginning retained earnings as of September 30, 2017. We did not record any adjustments to retained earnings for the tax effect of the adoption of ASU 2016-09 as we have a full valuation allowance position against our U.S. deferred tax asset. ASU 2016-09 requires all excess tax benefits and tax deficiencies to be recorded in the consolidated income statement on a prospective basis when the awards vest or are settled. Due to our full U.S. valuation allowance, ASU 2016-09 had no impact to our tax expense for fiscal year 2018. Pronouncements for Adoption in Subsequent Periods In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). In March, April, May and December 2016, the FASB issued additional guidance related to Topic 606. The new standard superseded nearly all existing revenue recognition guidance. Under Topic 606, an entity is required to recognize revenue upon transfer of promised goods or services to customers in an amount that reflects the expected consideration to be received in exchange for those goods or services. Topic 606 defines a five-step process in order to achieve this core principle, which may require the use of judgment and estimates, and also requires expanded qualitative and quantitative disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers, including significant judgments and estimates used. The new standard also defines accounting for certain costs related to origination and fulfillment of contracts with customers, including whether such costs should be capitalized. The new standard permits adoption either by using (i) a full retrospective approach for all periods presented in the period of adoption or (ii) a modified retrospective approach where the new standard is applied in the financial statements starting with the year of adoption. Under both approaches, cumulative impact of the adoption is reflected as an adjustment to retained earnings (accumulated deficit) as of the earliest date presented in accordance with the new standard. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers: Deferral of the Effective Date , which delayed the effective date of the new standard from January 1, 2017 to January 1, 2018. We plan to implement the new guidance as of September 29, 2018, the beginning of our next fiscal year, using the modified retrospective approach, applied to those contracts that were not completed as of that date. We developed a project plan for the implementation of the guidance, including a review of our revenue streams to identify any differences in the timing, measurement or presentation of revenue recognition and costs to obtain or fulfill the contracts. We have completed our assessment of the impacts of the standard, including any impacts from issued amendments, and have determined that the cumulative effect of the adoption of this new standard is not material. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . This update makes amendments to the guidance in U.S. GAAP on the classification and measurement of financial instruments. The new standard significantly revises an entity's accounting related to (1) the classification and measurement of investments in equity securities and (2) the presentation of certain fair value changes for financial liabilities measured at fair value. It also amends certain disclosure requirements associated with the fair value of financial instruments. ASU 2016-01 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We do not expect the updated standard to have a material impact on our consolidated financial statements and related disclosures. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . In September 2017 and January and July of 2018, the FASB issued additional guidance related to Topic 842. The new standard increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. Certain qualitative and quantitative disclosures are required, as well as a retrospective recognition and measurement of impacted leases. The new guidance is effective for fiscal years and interim periods within those years beginning after December 15, 2018, with early adoption permitted. We are evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures and we anticipate that this new guidance will materially impact our financial statements as we have a significant number of operating leases. In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments . This update amends the guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For available for sale debt securities, credit losses should be measured in a manner similar to current GAAP; however, this update will require that credit losses be presented as an allowance rather than as a write-down. ASU 2016-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. We are evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures. In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments . This update addresses debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions and separately identifiable cash flows and application of the predominance principle. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We are evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures. In October 2016, the FASB issued ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory . This update amends the guidance on recognizing the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. Consequently, the amendment eliminates the exception for an intra entity transfer of an asset other than inventory. ASU 2016-16 is effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. We are evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Sep. 28, 2018
Accounting Policies [Abstract]
Schedule of Estimated Useful Life	Property and equipment are depreciated or amortized using the straight-line method over the following estimated useful lives: Asset Classification Estimated Useful Life In Years Buildings and improvements 20 – 40 Capital lease assets 5 - 20 Machinery and equipment 2 – 7 Computer equipment and software 2 – 5 Furniture and fixtures 7 – 10 Leasehold improvements Shorter of useful life or term of lease

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Sep. 28, 2018
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	The following table summarizes the total estimated acquisition consideration (in thousands): Cash consideration paid to AppliedMicro common stockholders $ 287,060 Common stock issued (9,544,125 shares of our common stock at $47.53 per share) 453,632 Equity consideration for vested "in-the-money" stock options and unvested restricted stock units 2,143 Fair value of the replacement equity awards attributable to pre-acquisition service 9,307 Total consideration paid, less cash acquired $ 752,142
Allocation of Purchase Price	The final allocation of purchase price as of December 30, 2016, is as follows (in thousands): Final Allocation Current assets $ 12,614 Intangible assets 20,900 Other assets 3,089 Total assets acquired 36,603 Other liabilities 7,201 Total liabilities assumed 7,201 Net assets acquired 29,402 Consideration: Cash paid upon closing, net of cash acquired 37,125 Goodwill $ 7,723 The final allocation of purchase price as of December 30, 2016, is as follows (in thousands): Final Allocation Current assets $ 10,445 Intangible assets 45,650 Other assets 3,317 Total assets acquired 59,412 Debt 11,627 Deferred income taxes 11,552 Other liabilities 4,294 Total liabilities assumed 27,473 Net assets acquired 31,939 Consideration: Cash paid upon closing, net of cash acquired 47,517 Goodwill $ 15,578 We finalized the purchase accounting during the fiscal quarter ended June 29, 2018. The final purchase price allocation is as follows (in thousands): As Reported Allocation Adjustments Final Allocation September 29, 2017 Current assets $ 7,375 $ (1,088 ) $ 6,287 Intangible assets 19,000 — 19,000 Other assets 3,301 (81 ) 3,220 Total assets acquired 29,676 (1,169 ) 28,507 Current liabilities 2,169 142 2,311 Other liabilities 190 275 465 Total liabilities assumed 2,359 417 2,776 Net assets acquired 27,317 (1,586 ) 25,731 Consideration: Cash paid upon closing, net of cash acquired 33,500 — 33,500 Goodwill $ 6,183 $ 1,586 $ 7,769 We finalized the purchase accounting during the fiscal quarter ended December 29, 2017. The final purchase price allocation is as follows (in thousands): As Reported Allocation Adjustments Final Allocation September 29, 2017 Current assets $ 70,434 $ (553 ) $ 69,881 Intangible assets 412,848 — 412,848 Assets held for sale 40,944 — 40,944 Other assets 9,800 — 9,800 Total assets acquired 534,026 (553 ) 533,473 Liabilities held for sale 4,444 — 4,444 Other liabilities 17,627 651 18,278 Total liabilities assumed 22,071 651 22,722 Net assets acquired 511,955 (1,204 ) 510,751 Consideration: Cash paid upon closing 230,298 — 230,298 Common stock issued 455,775 — 455,775 Equity instruments issued 9,307 — 9,307 Total consideration $ 695,380 $ — $ 695,380 Goodwill $ 183,425 $ 1,204 $ 184,629
Components of Acquired Intangible Assets on a Preliminary Basis	The components of the acquired intangible assets on a preliminary basis were as follows (in thousands): Amount Useful Lives (Years) Developed technology $ 1,000 7 Customer relationships 19,900 10 $ 20,900 The components of the acquired intangible assets were as follows (in thousands): Included In Assets Held For Sale Included In Retained Business Useful Lives (Years) Developed technology $ 9,600 $ 78,448 7 years Customer relationships — 334,400 14 years $ 9,600 $ 412,848 The components of the acquired intangible assets on a preliminary basis were as follows (in thousands): Amount Useful Lives (Years) Developed technology $ 9,400 7 Customer relationships 36,250 10 $ 45,650
Summary of Unaudited Supplemental Pro Forma Data	This pro forma data is presented for informational purposes only and does not purport to be indicative of our future results of operations. Fiscal Year Ended September 30, 2016 Revenue $ 551,964 Net (loss) income (3,324 ) This pro forma data is presented for informational purposes only and does not purport to be indicative of our future results of operations. Fiscal Year Ended September 30, 2016 Revenue $ 553,174 Net income 1,183 The following is a summary of FiBest revenue and earnings included in our accompanying consolidated statements of operations for the fiscal year ended September 30, 2016 (in thousands): Amount Revenue $ 30,540 Loss before income taxes (4,616 ) The following is a summary of AppliedMicro revenue and earnings included in our accompanying consolidated statements of operations for the fiscal year ended September 29, 2017 (in thousands): Amount Revenue $ 110,117 Loss from continuing operations (27,222 ) Loss from discontinued operations (44,599 ) This pro forma data is presented for informational purposes only and does not purport to be indicative of our future results of operations. Fiscal Year Ended September 29, 2017 September 30, 2016 Revenue $ 755,728 $ 707,299 Loss from continuing operations (104,828 ) (53,613 ) Loss from discontinued operations (43,734 ) (72,730 ) The following is a summary of Metelics revenue and earnings included in our accompanying consolidated statements of operations for the fiscal year ended September 30, 2016 (in thousands): Amount Revenue $ 33,552 Income before income taxes 3,372

Investments (Tables)

Investments (Tables)	12 Months Ended
	Sep. 28, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of Available for Sale Investments	The amortized cost, gross unrealized holding gains or losses and fair value of our available-for-sale investments by major investments type as of September 28, 2018 and September 29, 2017 are summarized in the tables below (in thousands): September 28, 2018 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value Corporate bonds $ 28,731 $ — $ (460 ) $ 28,271 Commercial paper 69,966 — (16 ) 69,950 Total investments $ 98,697 $ — $ (476 ) $ 98,221 September 29, 2017 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value Corporate bonds $ 26,366 $ 10 $ (166 ) $ 26,210 Commercial paper 57,943 4 (36 ) 57,911 Total investments $ 84,309 $ 14 $ (202 ) $ 84,121
Summary of Contractual Maturities of Investments	The contractual maturities of available-for-sale investments were as follows (in thousands): September 28, 2018 Less than 1 year $ 70,200 Over 1 year 28,021 Total investments $ 98,221

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Sep. 28, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis consist of the following (in thousands): September 28, 2018 Fair Value Active Markets for Identical Assets (Level 1) Observable Inputs (Level 2) Unobservable Inputs (Level 3) Assets Money market funds $ 253 $ 253 $ — $ — Commercial paper 69,950 — 69,950 — Corporate bonds 28,271 — 28,271 — Total assets measured at fair value $ 98,474 $ 253 $ 98,221 $ — Liabilities Contingent consideration $ 585 $ — $ — $ 585 Common stock warrant liability 13,129 — — 13,129 Total liabilities measured at fair value $ 13,714 $ — $ — $ 13,714 September 29, 2017 Fair Value Active Markets for Identical Assets (Level 1) Observable Inputs (Level 2) Unobservable Inputs (Level 3) Assets Money market funds $ 36 $ 36 $ — $ — Commercial paper 57,911 — 57,911 — Corporate bonds 26,210 — 26,210 — Total assets measured at fair value $ 84,157 $ 36 $ 84,121 $ — Liabilities Contingent consideration $ 1,679 $ — $ — $ 1,679 Warrant liability 40,775 — — 40,775 Total liabilities measured at fair value $ 42,454 $ — $ — $ 42,454
Quantitative Information Used in Fair Value Calculation of Level 3 Liabilities	The quantitative information utilized in the fair value calculation of our Level 3 liabilities are as follows: Liabilities Valuation Technique Unobservable Input September 28, 2018 September 29, 2017 Contingent consideration Discounted cash flow Discount rate 9.2% 9.2% Probability of achievement 90% 70% - 100% Timing of cash flows 1 month 2 - 8 months Warrant liability Black-Scholes model Volatility 60.7% 44.9% Discount rate 2.81% 1.62% Expected life 2.2 years 3.2 years Exercise price $14.05 $14.05 Stock price $20.60 $44.61 Dividend rate —% —%
Changes in Assets with Inputs Classified within Level 3 of Fair Value	The changes in assets and liabilities with inputs classified within Level 3 of the fair value hierarchy consist of the following (in thousands): Fiscal Year 2018 September 29, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 28, Contingent consideration $ 1,679 $ (394 ) $ — $ (700 ) $ — $ 585 Warrant liability $ 40,775 $ (27,646 ) $ — $ — $ — $ 13,129 Fiscal Year 2017 September 30, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 29, Contingent consideration $ 848 $ 180 $ 1,701 $ (1,050 ) $ — $ 1,679 Warrant liability $ 38,253 $ 2,522 $ — $ — $ — $ 40,775 Fiscal Year 2016 October 2, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 30, Contingent consideration $ 1,150 $ 98 $ — $ (400 ) $ — $ 848 Warrant liability $ 21,822 $ 16,431 $ — $ — $ — $ 38,253
Changes in Liabilities with Inputs Classified within Level 3 of Fair Value	The changes in assets and liabilities with inputs classified within Level 3 of the fair value hierarchy consist of the following (in thousands): Fiscal Year 2018 September 29, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 28, Contingent consideration $ 1,679 $ (394 ) $ — $ (700 ) $ — $ 585 Warrant liability $ 40,775 $ (27,646 ) $ — $ — $ — $ 13,129 Fiscal Year 2017 September 30, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 29, Contingent consideration $ 848 $ 180 $ 1,701 $ (1,050 ) $ — $ 1,679 Warrant liability $ 38,253 $ 2,522 $ — $ — $ — $ 40,775 Fiscal Year 2016 October 2, Net Realized/Unrealized Losses (Gains) Included in Earnings Purchases and Issuances Sales and Settlements Transfers in and/or (out) of Level 3 September 30, Contingent consideration $ 1,150 $ 98 $ — $ (400 ) $ — $ 848 Warrant liability $ 21,822 $ 16,431 $ — $ — $ — $ 38,253

Accounts Receivables Allowanc_2

Accounts Receivables Allowances (Tables)	12 Months Ended
	Sep. 28, 2018
Receivables [Abstract]
Rollforward of Accounts Receivable Allowances	Summarized below is the activity in our accounts receivable allowances including compensation credits and doubtful accounts as follows (in thousands): Fiscal Year 2018 2017 2016 Balance - beginning of year $ 9,410 $ 3,279 $ 5,745 Provision, net 15,465 29,512 10,453 Charge-offs (18,080 ) (23,381 ) (12,919 ) Balance - end of year $ 6,795 $ 9,410 $ 3,279

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Sep. 28, 2018
Inventory Disclosure [Abstract]
Components of Inventories	Inventories consist of the following (in thousands): September 28, 2018 September 29, 2017 Raw materials $ 71,408 $ 78,999 Work-in-process 13,466 13,962 Finished goods 37,963 43,113 Total $ 122,837 $ 136,074

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Sep. 28, 2018
Property, Plant and Equipment [Abstract]
Components of Property, Plant and Equipment	Property, plant and equipment consist of the following (in thousands): September 28, September 29, Construction in process 49,661 22,195 Machinery and equipment 174,638 160,955 Leasehold improvements 14,984 13,809 Furniture and fixtures 2,306 2,078 Capital lease assets 19,380 20,410 Computer equipment and software 17,317 16,539 Total property and equipment 278,286 235,986 Less accumulated depreciation and amortization (128,363 ) (104,967 ) Property and equipment — net $ 149,923 $ 131,019

Debt (Tables)

Debt (Tables)	12 Months Ended
	Sep. 28, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	All principal amounts outstanding and interest rate information as of September 28, 2018 , for the Credit Agreement were as follows (in thousands, except rate data): Principal Outstanding LIBOR Rate Margin Effective Interest Rate Term loans $679,856 2.24% 2.25% 4.49%
Schedule of Remained Outstanding on Term Loans	As of September 28, 2018 , the following remained outstanding on the Term Loans: Principal balance $ 679,856 Unamortized discount (4,625 ) Unamortized deferred financing costs (9,974 ) Total term loans 665,257 Current portion 6,885 Long-term, less current portion $ 658,372
Schedule of Minimum Principal Payments under Term Loans	As of September 28, 2018 , the minimum principal payments under the Term Loans in future fiscal years were as follows (in thousands): 2019 $ 6,885 2020 6,885 2021 6,885 2022 6,885 2023 6,885 Thereafter 645,431 Total $ 679,856

Capital Lease and Financing O_2

Capital Lease and Financing Obligations (Tables)	12 Months Ended
	Sep. 28, 2018
Capital Lease and Financing Obligations [Abstract]
Schedule of Future Minimum Lease Payments for Capital Leases	As of September 28, 2018 , future minimum payments under capital lease obligations related to all of our in service Leases were as follows (in thousands): Fiscal year ending: Amount 2019 $ 2,797 2020 2,760 2021 2,686 2022 2,547 2023 2,563 Thereafter 42,247 Total minimum capital lease payments $ 55,600 Less amount representing interest (27,786 ) Present value of net minimum capital lease payments $ 27,814

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Sep. 28, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments for Operating Leases	Future minimum lease payments for the next five fiscal years as of September 28, 2018 , are as follows (in thousands): 2019 $ 10,068 2020 7,527 2021 5,442 2022 3,766 2023 3,356 Thereafter 4,663 Total minimum lease payments $ 34,822

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Sep. 28, 2018
Other Liabilities Disclosure [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): September 28, September 29, Compensation and benefits $ 22,935 $ 32,505 Distribution costs 10,670 5,777 Product warranty 5,756 3,672 Professional fees 1,875 2,140 Rent and utilities 1,660 1,257 Contingent consideration 585 1,679 Income taxes payable 415 4,184 Purchase price holdback 375 1,000 Restructuring costs 89 627 Other 5,585 5,402 Total $ 49,945 $ 58,243

Restructurings (Tables)

Restructurings (Tables)	12 Months Ended
	Sep. 28, 2018
Restructuring and Related Activities [Abstract]
Summary of Costs Related to Restructuring Actions	The following is a summary of the costs incurred and remaining balances included in accrued expenses related to restructuring actions taken (in thousands): Fiscal Years 2018 2017 2016 Balance - beginning of year $ 627 $ 3,104 $ 943 Expense 6,265 2,744 3,465 Charges paid/settled (6,803 ) (5,221 ) (1,304 ) Balance - end of year $ 89 $ 627 $ 3,104

Product Warranties (Tables)

Product Warranties (Tables)	12 Months Ended
	Sep. 28, 2018
Guarantees [Abstract]
Schedule of Product Warranty Liability Activity	Product warranty liability activity is as follows (in thousands): Fiscal Years 2018 2017 2016 Balance — beginning of year $ 3,672 $ 1,039 $ 656 (Divested)/acquired (49 ) 952 413 Provisions/(expense) 1,865 1,737 (30 ) Direct charges/(payments) 268 (56 ) — Balance — end of year $ 5,756 $ 3,672 $ 1,039

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Sep. 28, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Amortization Expense Related to Amortizable Intangible Assets	Amortization expense related to intangible assets is as follows (in thousands): Fiscal Years 2018 2017 2016 Cost of revenue $ 33,429 $ 30,286 $ 26,615 Selling, general and administrative 48,265 35,456 23,640 Total $ 81,694 $ 65,742 $ 50,255
Summary of Intangible Assets	Intangible assets consist of the following (in thousands): September 28, September 29, Acquired technology $ 251,673 $ 251,655 Customer relationships 518,234 556,648 Trade name 3,400 3,400 Total 773,307 811,703 Less accumulated amortization (260,522 ) (190,611 ) Intangible assets — net $ 512,785 $ 621,092
Summary of Activity in Intangible Assets and Goodwill	A summary of the activity in intangible assets and goodwill follows (in thousands): Intangible Assets Total Intangibles Acquired Customer In-Process Research and Development Trade Name Total Goodwill Balance at September 30, 2016 $ 384,471 $ 165,397 $ 207,674 $ 8,000 $ 3,400 $ 120,024 Acquired 436,181 83,518 352,663 — — 195,145 Placed in service — 3,648 — (3,648 ) — — Fair value adjustment — — — — — 220 Currency translation adjustments (4,597 ) (908 ) (3,689 ) — — (1,624 ) Impairments of intangible assets (4,352 ) — — (4,352 ) — — Balance at September 29, 2017 811,703 251,655 556,648 — 3,400 313,765 Allocation to divested business (39,285 ) — (39,285 ) — — (2,560 ) Fair value adjustment — — — — — 2,790 Currency translation adjustments 889 18 871 — — 81 Balance at September 28, 2018 $ 773,307 $ 251,673 $ 518,234 $ — $ 3,400 $ 314,076
Summary of Estimated Amortization of Intangible Assets in Future Fiscal Years	As of September 28, 2018 , our estimated amortization of our intangible assets in future fiscal years, was as follows (in thousands): 2019 2020 2021 2022 2023 Thereafter Amortization expense $ 83,749 81,669 74,061 61,830 51,466 156,610

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Sep. 28, 2018
Income Tax Disclosure [Abstract]
Components of Deferred Tax Assets and Liabilities	The components of our deferred tax assets and liabilities are as follows (in thousands): September 28, September 29, Deferred tax assets (liabilities): Federal and foreign net operating losses and credits $ 321,982 $ 396,871 Intangible assets (94,929 ) (180,544 ) Property and equipment (6,293 ) (1,045 ) Other non-current deferred tax assets 13,850 20,756 Deferred compensation 3,810 9,291 Deferred gain 6,575 14,853 Valuation allowance (243,112 ) (274,406 ) Total deferred tax (liability) asset $ 1,883 $ (14,224 )
Summary of Domestic and Foreign Income (Loss) from Continuing Operations Before Taxes	The domestic and foreign income (loss) from continuing operations before taxes were as follows (in thousands): Fiscal Years 2018 2017 2016 United States $ (145,851 ) $ (111,432 ) $ (46,593 ) Foreign (9,384 ) 61,927 25,022 (Loss) income from operations before income taxes $ (155,235 ) $ (49,505 ) $ (21,571 )
Components of Provision (Benefit) for Income Taxes	The components of the provision (benefit) for income taxes are as follows (in thousands): Fiscal Years 2018 2017 2016 Current: Federal $ (6,876 ) $ 100 $ (5,861 ) State (160 ) 225 (766 ) Foreign 1,642 7,307 906 Current provision (benefit) (5,394 ) 7,632 (5,721 ) Deferred: Federal 75,428 (42,637 ) (8,163 ) State (15,526 ) (4,037 ) (502 ) Foreign (24,652 ) (466 ) (2,603 ) Change in valuation allowance (51,329 ) 140,419 (994 ) Deferred provision (benefit) (16,079 ) 93,279 (12,262 ) Total provision (benefit) $ (21,473 ) $ 100,911 $ (17,983 )
Reconciliation of Effective Tax Rates	Our effective tax rates differ from the federal and statutory rate as follows: Fiscal Years 2018 2017 2016 Federal statutory rate 24.5% 35.0% 35.0% Foreign rate differential 5.1 31.9 40.1 State taxes net of federal benefit 0.8 0.2 1.0 Warrant liabilities 4.4 (1.8) (26.7) Change in valuation allowance 34.0 (270.0) 3.0 Research and development credits 9.0 12.8 16.9 Correction of prior period — — 18.3 Provision to return adjustments 8.3 (4.0) 3.5 Nondeductible compensation expense 1.4 (4.1) (9.2) Nondeductible legal fees 0.9 (3.9) (1.8) 2017 tax reform (73.7) — — Other permanent differences (0.9) 0.1 3.3 Effective income tax rate 13.8% (203.8)% 83.4%
Activity Related to Unrecognized Tax Benefits	Activity related to unrecognized tax benefits is as follows (in thousands): Amount Balance - September 30, 2016 (1,670 ) Additions based on tax positions — Reductions based on tax positions — Balance - September 29, 2017 $ (1,670 ) Additions based on tax positions — Reductions based on tax positions 1,370 Balance at September 28, 2018 $ (300 )
Summary of Fiscal Tax Years Examination by Jurisdictions	A summary of the fiscal tax years that remain subject to examination, as of September 28, 2018 , for the Company’s significant tax jurisdictions are: Jurisdiction Tax Years Subject to Examination United States—federal 2015 - forward United States—various states 2014 - forward Ireland 2016 - forward

Share - Based Compensation Pl_2

Share - Based Compensation Plans (Tables)	12 Months Ended
	Sep. 28, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Effects of Stock-Based Compensation Expense Related to Stock-Based Awards to Employees and Nonemployees	The following table shows a summary of share-based compensation expense included in the Consolidated Statement of Operations during the periods presented (in thousands): Fiscal Years 2018 2017 2016 Cost of revenue $ 3,869 $ 3,189 $ 2,150 Research and development 13,448 10,565 6,568 Selling, general and administrative 14,620 22,581 18,236 Total $ 31,937 $ 36,335 $ 26,954
Summary of Stock Option Activity	A summary of stock option activity for fiscal year 2018 is as follows (in thousands, except per share amounts and contractual term): Number of Shares Weighted-Average Exercise Price per Share Weighted-Average Remaining Contractual Term (in Years) Aggregate Intrinsic Value Options outstanding - September 29, 2017 1,177 $ 31.61 Granted 405 36.58 Exercised (27 ) 2.87 Forfeited, canceled or expired (147 ) 46.29 Options outstanding - September 28, 2018 1,408 $ 32.05 4.93 $ 1,850 Options vested and expected to vest - September 28, 2018 1,408 $ 32.05 4.93 $ 1,850 Options exercisable - September 28, 2018 343 $ 19.08 3.77 $ 1,850
Weighted Average Assumptions used for Calculating Fair Value of Stock Options Granted	The weighted average Black-Scholes input assumptions used for calculating the fair value of these performance-based stock options are as follows: Fiscal Years 2016 Risk-free interest rate 1.15 % Expected term (years) 4.0 Expected volatility 31.8 % Expected dividends — % The weighted average Monte Carlo input assumptions used for calculating the fair value of these market-based stock options are as follows: Fiscal Years 2018 2017 2016 Risk-free interest rate 2.3 % 1.9 % 2.1 % Expected term (years) 3.4 7.0 7.0 Expected volatility 45.8 % 32.3 % 36.5 % Target price $98.99 $67.39 $64.22
Summary of Restricted Stock Awards and Unit Activity	A summary of restricted stock awards and units activity for fiscal year 2018 is as follows (in thousands): Number of Shares Weighted-Average Grant Date Fair Value Aggregate Intrinsic Value Issued and unvested - September 29, 2017 1,907 $ 39.20 $ 85,093 Granted 1,145 26.68 Vested (906 ) 35.24 Forfeited, canceled or expired (274 ) 34.56 Issued and unvested shares - September 28, 2018 1,872 34.15 $ 38,452

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Sep. 28, 2018
Discontinued Operations and Disposal Groups [Abstract]
Summary of Operating Results Related to Divested Businesses	The accompanying consolidated statement of operations includes the following operating results related to these discontinued operations (in thousands): Fiscal Years 2018 2017 2016 Revenue (1) $ — $ 660 $ — Cost of revenue (1) (596 ) 2,252 — Gross (loss) profit 596 (1,592 ) — Operating expenses: Research and development (1) 5,251 29,167 — Selling, general and administrative (1) 1,560 13,840 — Total operating expenses 6,811 43,007 — (Loss) income from discontinued operations (1) (6,215 ) (44,599 ) — Other income (2) — 7,500 7,500 Gain on sale (2) — 18,022 308 (Loss) income before income taxes (6,215 ) (19,077 ) 7,808 Income tax provision (benefit) — — 2,786 (Loss) income from discontinued operations (6,215 ) (19,077 ) 5,022 Cash flow from Operating Activities (1) (10,734 ) (42,776 ) — Cash flow from Investing Activities (2) — 25,522 7,500

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Sep. 28, 2018
Earnings Per Share [Abstract]
Computation for Basic and Diluted Net Income (Loss) Per Share of Common Stock	The following table set forth the computation for basic and diluted net income (loss) per share of common stock (in thousands, except per share data): Fiscal Years 2018 2017 2016 Numerator: Loss from continuing operations $ (133,762 ) $ (150,416 ) $ (3,588 ) (Loss) income from discontinued operations (6,215 ) (19,077 ) 5,022 Net (loss) income (139,977 ) (169,493 ) 1,434 Warrant liability gain (27,646 ) — — Net (loss) income attributable to common stockholders $ (167,623 ) $ (169,493 ) $ 1,434 Denominator: Weighted average common shares outstanding-basic 64,741 60,704 53,364 Dilutive effect of warrants 570 — — Weighted average common shares outstanding-diluted 65,311 60,704 53,364 Common stock earnings per share-basic: Continuing operations $ (2.07 ) $ (2.48 ) $ (0.07 ) Discontinued operations (0.10 ) (0.31 ) 0.09 Net common stock earnings per share-basic $ (2.16 ) $ (2.79 ) $ 0.03 Common stock earnings per share-diluted: Continuing operations $ (2.47 ) $ (2.48 ) $ (0.07 ) Discontinued operations (0.10 ) (0.31 ) 0.09 Net common stock earnings per share-diluted $ (2.57 ) $ (2.79 ) $ 0.03

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Sep. 28, 2018
Supplemental Cash Flow Elements [Abstract]
Schedule of Supplemental Cash Flow Information Regarding Noncash Investing and Financing Activities	The following is supplemental cash flow information regarding non-cash investing and financing activities (in thousands): Fiscal Years 2018 2017 2016 Cash paid for interest $ 29,698 $ 30,529 $ 16,335 Cash paid (refunded) for income taxes $ 3,559 $ (3,161 ) $ (373 )

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Sep. 28, 2018
Equity [Abstract]
Summary of Accumulated Other Comprehensive Income, Net of Income Taxes	The components of accumulated other comprehensive income (loss), net of income taxes, are as follows: Foreign Currency Items Other Items Total Balance - September 30, 2016 $ 9,138 $ (99 ) $ 9,039 Foreign currency translation, net of tax (5,999 ) — (5,999 ) Unrealized gain/loss on short-term investments, net of tax — (63 ) (63 ) Balance - September 29, 2017 3,139 (162 ) 2,977 Foreign currency translation, net of tax (502 ) — (502 ) Unrealized gain/loss on short-term investments, net of tax — (287 ) (287 ) Balance at September 28, 2018 $ 2,637 $ (449 ) $ 2,188

Geographic and Significant Cu_2

Geographic and Significant Customer Information (Tables)	12 Months Ended
	Sep. 28, 2018
Segment Reporting [Abstract]
Summary of Different Geographic Regions	Information about our operations in different geographic regions, based upon customer locations, is presented below (in thousands): Fiscal Years Revenue by Geographic Region 2018 2017 2016 United States $ 272,951 $ 265,038 $ 155,998 China 159,763 206,136 201,911 Asia Pacific, excluding China (1) 79,581 170,826 144,872 Other Countries (2) 58,103 56,772 41,557 Total $ 570,398 $ 698,772 $ 544,338 (1) Asia Pacific represents Taiwan, Japan, Singapore, India, Thailand, South Korea, Australia, Malaysia, New Zealand, the Philippines and Vietnam. (2) No international country or region represented greater than 10% of the total revenue as of the dates presented, other than China and the Asia-Pacific region as presented above. As of September 28, September 29, Long-Lived Assets by Geographic Region United States $ 122,888 $ 101,044 Asia Pacific (1) 24,702 24,945 Other Countries (2) 2,333 5,030 Total $ 149,923 $ 131,019 (1) Asia Pacific represents Taiwan, Japan, Singapore, India, Thailand, South Korea, Malaysia, the Philippines, Vietnam and China. (2) No international country or region represented greater than 10% of the total net long-lived assets as of the dates presented, other than the Asia-Pacific region as presented above.
Summary of Customer Concentrations as Percentage of Total Sales and Accounts Receivable	The following is a summary of customer concentrations as a percentage of total sales and accounts receivable as of and for the periods presented: Fiscal Years Revenue 2018 2017 2016 Customer A 13 % 11 % 11 % Customer B 6 % 10 % 15 % Customer C 2 % 6 % 12 % September 28, September 29, Accounts Receivable Customer A 19 % 13 % Customer D 26 % 14 %

Quarterly Financial Data (Una_2

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Sep. 28, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data	(In thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Fiscal Year Fiscal Year 2018 Revenue $ 130,925 $ 150,414 $ 137,872 $ 151,187 $ 570,398 Gross profit 60,954 65,601 48,169 70,982 245,706 Loss from continuing operations (16,970 ) (15,466 ) (85,210 ) (16,116 ) (133,762 ) Loss from discontinued operations (1) (5,599 ) (18 ) (220 ) (378 ) (6,215 ) Per share data (2) Loss from continuing operations, basic $ (0.26 ) $ (0.24 ) $ (1.31 ) $ (0.25 ) $ (2.07 ) Loss from discontinued operations, basic $ (0.09 ) $ 0.00 $ 0.00 $ (0.01 ) $ (0.10 ) Per share data (2) (3) Loss from continuing operations, diluted $ (0.49 ) $ (0.50 ) $ (1.31 ) $ (0.29 ) $ (2.47 ) Loss from discontinued operations, diluted $ (0.09 ) $ 0.00 $ 0.00 $ (0.01 ) $ (0.10 ) Fiscal Year 2017 Revenue $ 151,752 $ 186,084 $ 194,555 $ 166,381 $ 698,772 Gross profit 78,495 68,864 92,629 86,896 326,884 Loss from continuing operations (2,171 ) (134,267 ) (13,977 ) (1 ) (150,416 ) Income (loss) from discontinued operations (1) 1,206 4,136 (13,700 ) (10,719 ) (19,077 ) Per share data (2) Loss from continuing operations, basic $ (0.04 ) $ (2.21 ) $ (0.22 ) $ 0.00 $ (2.48 ) Income (loss) from discontinued operations, basic $ 0.02 $ 0.07 $ (0.21 ) $ (0.17 ) $ (0.31 ) Per share data (2) (3) Loss from continuing operations, diluted $ (0.04 ) $ (2.21 ) $ (0.22 ) $ (0.21 ) $ (2.48 ) Income (loss) from discontinued operations, diluted $ 0.02 $ 0.07 $ (0.21 ) $ (0.16 ) $ (0.31 ) ____________ (1) During the second quarter of fiscal year 2017, we announced a plan to divest the Compute business of AppliedMicro, and have included the results of the Compute business as discontinued operations in each subsequent quarter. (2) Earnings per share calculations for each of the quarters are based on the weighted average number of shares outstanding and included common stock equivalents in each period. Therefore, the sums of the quarters do not necessarily equal the full year earnings per share. (3) Diluted (loss) income per share for the fiscal first, second and fourth quarters of 2018 and the fiscal fourth quarter 2017 excluded $14.6 million , $17.0 million , $2.8 million and $14.0 million , respectively, related to warrant liability gain

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 30, 2018USD ($)	Sep. 29, 2017USD ($)	Jul. 01, 2016USD ($)	Sep. 28, 2018USD ($)segment	Sep. 29, 2017USD ($)	Sep. 30, 2016USD ($)
Description Of Business And Basis Of Presentation [Line Items]
Number of reportable operating segments | segment				1
Impairments of intangible assets					$ (4,352)
Impairment related charges			$ 13,800	$ 9,143	4,352	$ 12,955
Term of product warranties				12 months
Change in estimate, rolling average period				12 months
Minimum
Description Of Business And Basis Of Presentation [Line Items]
Definite-lived intangible asset useful life				5 years
Maximum
Description Of Business And Basis Of Presentation [Line Items]
Definite-lived intangible asset useful life				14 years
Accounting Standards Update 2016-09 | Accumulated Deficit
Description Of Business And Basis Of Presentation [Line Items]
Cumulative effect of change on equity				$ 1,000
Disposal Group, Not Discontinued Operations | LR4
Description Of Business And Basis Of Presentation [Line Items]
Gain (loss) on disposal				$ 34,300
Operating Expense
Description Of Business And Basis Of Presentation [Line Items]
Impairment related charges	$ 6,600
Operating Expense | Fixed Assets
Description Of Business And Basis Of Presentation [Line Items]
Impairment related charges	4,600
Operating Expense | Accounts Receivable
Description Of Business And Basis Of Presentation [Line Items]
Impairment related charges	$ 2,000
In-process research and development
Description Of Business And Basis Of Presentation [Line Items]
Impairments of intangible assets		$ (4,400)			$ (4,352)

Summary of Significant Accoun_5

Summary of Significant Accounting policies - Schedule of Estimated Useful Life (Detail)	12 Months Ended
	Sep. 28, 2018
Minimum | Buildings and improvements
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	20 years
Minimum | Capital lease assets
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	5 years
Minimum | Machinery and equipment
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	2 years
Minimum | Computer equipment and software
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	2 years
Minimum | Furniture and fixtures
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	7 years
Maximum | Buildings and improvements
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	40 years
Maximum | Capital lease assets
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	20 years
Maximum | Machinery and equipment
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	7 years
Maximum | Computer equipment and software
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	5 years
Maximum | Furniture and fixtures
Property Plant And Equipment Estimated Useful Lives [Line Items]
Estimated Useful Life In Years	10 years

Acquisitons - Additional Inform

Acquisitons - Additional Information (Detail) - USD ($) $ in Thousands	Aug. 09, 2017	Jul. 31, 2017	May 26, 2017	Jan. 26, 2017	Dec. 14, 2015	Dec. 09, 2015	Dec. 29, 2017	Jun. 29, 2018	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016	Dec. 30, 2016
Business Acquisition [Line Items]
Equity interests issued and issuable				$ 465,100					$ 0	$ 465,082	$ 0
Purchase price holdback									375	1,000
Goodwill									314,076	313,765
Contingent consideration									585	1,679
Aggregate cash consideration									1,000	270,008	85,517
Applied Micro Circuits Corporation
Business Acquisition [Line Items]
Aggregate consideration				695,400					695,380
Cash paid				287,100
Cash acquired from acquisition				56,800
Equity interests issued and issuable				465,100
Equity interests issued and issuable				453,632
Transaction costs									$ 0	11,900
Weighted average life of identified intangible assets acquired									12 years 8 months 12 days
Payments to acquire businesses				287,060
Goodwill									$ 184,629
Intangible assets									412,848
Aggregate cash consideration									230,298
Debt assumed									4,444
Applied Micro Circuits Corporation | Equity Issuance Costs
Business Acquisition [Line Items]
Transaction costs										1,000
Applied Micro Circuits Corporation | Adjustment
Business Acquisition [Line Items]
Aggregate consideration									0
Goodwill									1,204
Intangible assets									0
Aggregate cash consideration									0
Debt assumed									0
Picometrix
Business Acquisition [Line Items]
Aggregate consideration	$ 29,500
Transaction costs									0	200
Payments to acquire businesses	33,500							$ 33,500		33,500
Indemnification assets	$ 4,000
Goodwill								7,769		6,183
Intangible assets								$ 19,000		19,000
Picometrix | Adjustment
Business Acquisition [Line Items]
Payments to acquire businesses									0
Goodwill									1,586
Intangible assets									$ 0
FiBest Limited
Business Acquisition [Line Items]
Aggregate consideration						$ 59,100
Weighted average life of identified intangible assets acquired									9 years 4 months 24 days
Goodwill												$ 15,578
Intangible assets												45,650
Aggregate cash consideration						47,500	$ 47,517
Debt assumed						$ 11,600						11,627
FiBest Limited | Selling, general and administrative
Business Acquisition [Line Items]
Transaction costs										0	$ 2,700
Aeroflex/Metelics Inc.
Business Acquisition [Line Items]
Weighted average life of identified intangible assets acquired									9 years 10 months 24 days
Goodwill												7,723
Intangible assets												$ 20,900
Aggregate cash consideration					$ 37,100		$ 37,125
Aeroflex/Metelics Inc. | Selling, general and administrative
Business Acquisition [Line Items]
Transaction costs									$ 0	$ 500
Antario
Business Acquisition [Line Items]
Aggregate consideration		$ 4,800
Payments to acquire businesses		5,800
Purchase price holdback		$ 1,000
Goodwill									1,600
Intangible assets									4,100
Triple Play Communications
Business Acquisition [Line Items]
Aggregate consideration			$ 2,200
Payments to acquire businesses			2,600
Goodwill									3,700
Intangible assets									200
Contingent consideration			$ 400
Employee Stock Options And Restricted Stock | Applied Micro Circuits Corporation
Business Acquisition [Line Items]
Equity interest issued or issuable value assigned				14,500
Equity interests issued and issuable				$ 9,300					9,307
Employee Stock Options And Restricted Stock | Applied Micro Circuits Corporation | Adjustment
Business Acquisition [Line Items]
Equity interests issued and issuable									$ 0

Acquisitions - Schedule of Aggr

Acquisitions - Schedule of Aggregate Purchase Price Allocated to Tangible and Identifiable Intangible Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ / shares in Units, $ in Thousands	Aug. 09, 2017	Jan. 26, 2017	Dec. 14, 2015	Dec. 09, 2015	Dec. 29, 2017	Jun. 29, 2018	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016	Dec. 30, 2016
Consideration:
Cash paid upon closing, net of cash acquired							$ 1,000	$ 270,008	$ 85,517
Goodwill							314,076	313,765
Equity interests issued and issuable		$ 465,100					0	465,082	$ 0
Applied Micro Circuits Corporation
Business Acquisition [Line Items]
Payments to acquire businesses		287,060
Current assets							69,881
Intangible assets							412,848
Assets held for sale							40,944
Other assets							9,800
Total assets acquired							533,473
Liabilities assumed:
Debt							4,444
Other liabilities							18,278
Total liabilities assumed							22,722
Net assets acquired							510,751
Consideration:
Cash paid upon closing, net of cash acquired							230,298
Goodwill							184,629
Equity interests issued and issuable		453,632
Equity consideration for vested in-the-money stock options and unvested restricted stock units		2,143
Fair value of the replacement equity awards attributable to pre-acquisition service		9,307
Total consideration		695,400					695,380
Total consideration paid, less cash acquired		$ 752,142
Equity interest issued (in shares)		9,544,125
Share price (in USD per share)		$ 47.53
Applied Micro Circuits Corporation | Preliminary Allocation as of September 30, 2016
Business Acquisition [Line Items]
Current assets								70,434
Intangible assets								412,848
Assets held for sale								40,944
Other assets								9,800
Total assets acquired								534,026
Liabilities assumed:
Debt								4,444
Other liabilities								17,627
Total liabilities assumed								22,071
Net assets acquired								511,955
Consideration:
Cash paid upon closing, net of cash acquired								230,298
Goodwill								183,425
Total consideration								695,380
Applied Micro Circuits Corporation | Allocation Adjustments
Business Acquisition [Line Items]
Current assets							(553)
Intangible assets							0
Assets held for sale							0
Other assets							0
Total assets acquired							(553)
Liabilities assumed:
Debt							0
Other liabilities							651
Total liabilities assumed							651
Net assets acquired							(1,204)
Consideration:
Cash paid upon closing, net of cash acquired							0
Goodwill							1,204
Total consideration							0
Aeroflex/Metelics Inc.
Business Acquisition [Line Items]
Current assets										$ 12,614
Intangible assets										20,900
Other assets										3,089
Total assets acquired										36,603
Liabilities assumed:
Other liabilities										7,201
Total liabilities assumed										7,201
Net assets acquired										29,402
Consideration:
Cash paid upon closing, net of cash acquired			$ 37,100		$ 37,125
Goodwill										7,723
FiBest Limited
Business Acquisition [Line Items]
Current assets										10,445
Intangible assets										45,650
Other assets										3,317
Total assets acquired										59,412
Liabilities assumed:
Debt				$ 11,600						11,627
Deferred income taxes										11,552
Other liabilities										4,294
Total liabilities assumed										27,473
Net assets acquired										31,939
Consideration:
Cash paid upon closing, net of cash acquired				47,500	$ 47,517
Goodwill										$ 15,578
Total consideration				$ 59,100
Picometrix
Business Acquisition [Line Items]
Payments to acquire businesses	$ 33,500					$ 33,500		33,500
Current assets						6,287		7,375
Intangible assets						19,000		19,000
Other assets						3,220		3,301
Total assets acquired						28,507		29,676
Liabilities assumed:
Current liabilities						2,311		2,169
Other liabilities						465		190
Total liabilities assumed						2,776		2,359
Net assets acquired						25,731		27,317
Consideration:
Goodwill						$ 7,769		6,183
Total consideration	$ 29,500
Picometrix | Allocation Adjustments
Business Acquisition [Line Items]
Payments to acquire businesses							0
Current assets							(1,088)
Intangible assets							0
Other assets							(81)
Total assets acquired							(1,169)
Liabilities assumed:
Current liabilities							142
Other liabilities							275
Total liabilities assumed							417
Net assets acquired							(1,586)
Consideration:
Goodwill							1,586
Common Stock | Applied Micro Circuits Corporation
Consideration:
Equity interests issued and issuable							455,775
Common Stock | Applied Micro Circuits Corporation | Preliminary Allocation as of September 30, 2016
Consideration:
Equity interests issued and issuable								455,775
Common Stock | Applied Micro Circuits Corporation | Allocation Adjustments
Consideration:
Equity interests issued and issuable							0
Employee Stock Options And Restricted Stock | Applied Micro Circuits Corporation
Consideration:
Equity interests issued and issuable		$ 9,300					9,307
Employee Stock Options And Restricted Stock | Applied Micro Circuits Corporation | Preliminary Allocation as of September 30, 2016
Consideration:
Equity interests issued and issuable								$ 9,307
Employee Stock Options And Restricted Stock | Applied Micro Circuits Corporation | Allocation Adjustments
Consideration:
Equity interests issued and issuable							$ 0

Acquisitions - Components of Ac

Acquisitions - Components of Acquired Intangible Assets on a Preliminary Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets		$ 436,181
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets		83,518
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets		$ 352,663
Applied Micro Circuits Corporation
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 412,848
Applied Micro Circuits Corporation | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 78,448
Acquired intangible assets, Useful Lives (Years)	7 years
Applied Micro Circuits Corporation | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 334,400
Acquired intangible assets, Useful Lives (Years)	14 years
FiBest Limited
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 45,650
FiBest Limited | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 9,400
Acquired intangible assets, Useful Lives (Years)	7 years
FiBest Limited | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 36,250
Acquired intangible assets, Useful Lives (Years)	10 years
Aeroflex/Metelics Inc.
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 20,900
Aeroflex/Metelics Inc. | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 1,000
Acquired intangible assets, Useful Lives (Years)	7 years
Aeroflex/Metelics Inc. | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 19,900
Acquired intangible assets, Useful Lives (Years)	10 years
Discontinued Operations, Held-for-sale [Member] | Applied Micro Circuits Corporation
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 9,600
Discontinued Operations, Held-for-sale [Member] | Applied Micro Circuits Corporation | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	9,600
Discontinued Operations, Held-for-sale [Member] | Applied Micro Circuits Corporation | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets	$ 0

Acquisitions - Summary of Reven

Acquisitions - Summary of Revenue and Earnings (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
(Loss) income from discontinued operations	$ (378)	$ (220)	$ (18)	$ (5,599)	$ (10,719)	$ (13,700)	$ 4,136	$ 1,206	$ (6,215)	$ (19,077)	$ 5,022
Applied Micro Circuits Corporation
Business Acquisition [Line Items]
Revenue										110,117
Income (loss) before income taxes										(27,222)
(Loss) income from discontinued operations										(44,599)
FiBest Limited
Business Acquisition [Line Items]
Revenue										30,540
Income (loss) before income taxes										$ (4,616)
Aeroflex/Metelics Inc.
Business Acquisition [Line Items]
Revenue											33,552
Income (loss) before income taxes											$ 3,372

Acquisitions - Summary of Unaud

Acquisitions - Summary of Unaudited Supplemental Pro Forma Data (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 29, 2017	Sep. 30, 2016
Applied Micro Circuits Corporation
Business Acquisition [Line Items]
Revenue	$ 755,728	$ 707,299
Net (loss) income	(104,828)	(53,613)
Loss from discontinued operations	(43,734)	(72,730)
FiBest Limited
Business Acquisition [Line Items]
Revenue	551,964
Net (loss) income	$ (3,324)
Aeroflex/Metelics Inc.
Business Acquisition [Line Items]
Revenue		553,174
Net (loss) income		$ 1,183

Investments - Summary of Availa

Investments - Summary of Available for Sale Investments (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 98,697	$ 84,309
Gross Unrealized Holding Gains	0	14
Gross Unrealized Holding Losses	(476)	(202)
Aggregate Fair Value	98,221	84,121
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	28,731	26,366
Gross Unrealized Holding Gains	0	10
Gross Unrealized Holding Losses	(460)	(166)
Aggregate Fair Value	28,271	26,210
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	69,966	57,943
Gross Unrealized Holding Gains	0	4
Gross Unrealized Holding Losses	(16)	(36)
Aggregate Fair Value	$ 69,950	$ 57,911

Investments - Summary of Contra

Investments - Summary of Contractual Maturities of Investments (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Investments, Debt and Equity Securities [Abstract]
Less than 1 year	$ 70,200
Over 1 year	28,021
Total investments	$ 98,221	$ 84,121

Investments - Additional Inform

Investments - Additional Information (Detail) $ in Thousands	12 Months Ended
	Sep. 28, 2018USD ($)investment	Sep. 29, 2017USD ($)	Sep. 30, 2016USD ($)
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales of available-for-sale securities	$ 100,400	$ 44,600
Gross realized losses on available-for-sale securities	$ 300	100
Schedule of Available-for-sale Securities [Line Items]
Number of equity investments | investment	2
Loss on minority equity investment	$ 10,406	$ 0	$ 0
Preferred Stock | Privately Held Manufacturing Company
Schedule of Available-for-sale Securities [Line Items]
Investments	$ 5,000
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Minority investment (as a percent)	20.00%
Equity Securities | Compute
Schedule of Available-for-sale Securities [Line Items]
Investments	$ 36,500
Minority investment (as a percent)	20.00%
Initial value	$ 36,500
Loss on minority equity investment	10,400
Carrying value	$ 26,100

Fair Value - Assets and Liabili

Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 98,474	$ 84,157
Total liabilities measured at fair value	13,714	42,454
Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	585	1,679
Common stock warrant liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	13,129	40,775
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	28,271	26,210
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	253	36
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	69,950	57,911
Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	253	36
Total liabilities measured at fair value	0	0
Active Markets for Identical Assets (Level 1) | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	0	0
Active Markets for Identical Assets (Level 1) | Common stock warrant liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	0	0
Active Markets for Identical Assets (Level 1) | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0	0
Active Markets for Identical Assets (Level 1) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	253	36
Active Markets for Identical Assets (Level 1) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0	0
Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	98,221	84,121
Total liabilities measured at fair value	0	0
Observable Inputs (Level 2) | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	0	0
Observable Inputs (Level 2) | Common stock warrant liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	0	0
Observable Inputs (Level 2) | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	28,271	26,210
Observable Inputs (Level 2) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0	0
Observable Inputs (Level 2) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	69,950	57,911
Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0	0
Total liabilities measured at fair value	13,714	42,454
Unobservable Inputs (Level 3) | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	585	1,679
Unobservable Inputs (Level 3) | Common stock warrant liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	13,129	40,775
Unobservable Inputs (Level 3) | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0	0
Unobservable Inputs (Level 3) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0	0
Unobservable Inputs (Level 3) | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 0	$ 0

Fair Value - Quantitative Infor

Fair Value - Quantitative Information Used in Fair Value Calculation of Level 3 Liabilities (Details) - $ / shares	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Discount rate	7.20%
Unobservable Inputs (Level 3) | Discounted cash flow | Fair Value, Measurements, Recurring | Contingent consideration
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Discount rate	9.20%	9.20%
Probability of achievement	90.00%
Expected term	1 month
Unobservable Inputs (Level 3) | Discounted cash flow | Fair Value, Measurements, Recurring | Contingent consideration | Minimum
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Probability of achievement		70.00%
Expected term		2 months
Unobservable Inputs (Level 3) | Discounted cash flow | Fair Value, Measurements, Recurring | Contingent consideration | Maximum
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Probability of achievement		100.00%
Expected term		8 months
Unobservable Inputs (Level 3) | Black-Scholes model | Fair Value, Measurements, Recurring | Common stock warrant liability
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Discount rate	2.81%	1.62%
Expected term	2 years 2 months 23 days	3 years 2 months 23 days
Volatility	60.70%	44.90%
Exercise price (in USD per share)	$ 14.05	$ 14.05
Share price (in USD per share)	$ 20.60	$ 44.61
Dividend rate	0.00%	0.00%

Fair Value - Changes in Assets

Fair Value - Changes in Assets and Liabilities with Inputs Classified within Level 3 of Fair Value (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Contingent consideration
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 1,679	$ 848	$ 1,150
Net Realized/Unrealized Losses (Gains) Included in Earnings	(394)	180	(98)
Purchases and Issuances	0	1,701	0
Sales and Settlements	(700)	(1,050)	(400)
Transfers in and/or (out) of Level 3	0	0	0
Ending balance	585	1,679	848
Warrant liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	40,775	38,253	21,822
Net Realized/Unrealized Losses (Gains) Included in Earnings	(27,646)	2,522	(16,431)
Purchases and Issuances	0	0	0
Sales and Settlements	0	0	0
Transfers in and/or (out) of Level 3	0	0	0
Ending balance	$ 13,129	$ 40,775	$ 38,253

Accounts Receivables Allowanc_3

Accounts Receivables Allowances- Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance - beginning of year	$ 9,410	$ 3,279	$ 5,745
Provision, net	15,465	29,512	10,453
Charge-offs	(18,080)	(23,381)	(12,919)
Balance - end of year	6,795	9,410	3,279
Compensation Credits and Customer Returns Allowance
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance - beginning of year	8,900	3,000
Balance - end of year	6,300	8,900	3,000
Allowance for Doubtful Accounts
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance - beginning of year	300	200
Balance - end of year	$ 200	$ 300	$ 200

Inventories - Components of Inv

Inventories - Components of Inventories (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 71,408	$ 78,999
Work-in-process	13,466	13,962
Finished goods	37,963	43,113
Total	$ 122,837	$ 136,074

Property Plant and Equipment -

Property Plant and Equipment - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 278,286	$ 235,986
Less accumulated depreciation and amortization	(128,363)	(104,967)
Property and equipment — net	149,923	131,019
Construction in process
Property, Plant and Equipment [Line Items]
Total property and equipment	49,661	22,195
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	174,638	160,955
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	14,984	13,809
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	2,306	2,078
Capital lease assets
Property, Plant and Equipment [Line Items]
Total property and equipment	19,380	20,410
Less accumulated depreciation and amortization	(3,200)	(2,300)	$ (1,600)
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 17,317	$ 16,539

Property Plant and Equipment _2

Property Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 278,286	$ 235,986
Depreciation and amortization expense	30,700	27,300	$ 20,400
Accumulated depreciation	128,363	104,967
Capital lease assets
Property, Plant and Equipment [Line Items]
Total property and equipment	19,380	20,410
Accumulated depreciation	3,200	2,300	$ 1,600
Corporate Facility Leases | Capital lease assets
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 17,100	$ 16,900

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 28, 2018	May 09, 2018	May 02, 2018	Sep. 29, 2017
Debt Instrument [Line Items]
Debt instrument face amount	$ 700,000,000
Unamortized deferred financing costs	10,900,000
Term Loans
Debt Instrument [Line Items]
Unamortized deferred financing costs	9,974,000
Quarterly principal installments	$ 1,700,000
Maximum period for reinvestment of business divestiture proceeds	18 months
Maximum period for completion of reinvestment of business divestiture proceeds	6 months
Estimated fair value of term loans	$ 689,200,000			$ 696,200,000
Term Loans | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	2.24%
Term Loans | One Month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Term Loans | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Term Loans | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%
Term Loans | Minimum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
Revolving Credit Facility
Debt Instrument [Line Items]
Unamortized deferred financing costs	$ 900,000
Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	160,000,000
Remaining borrowing capacity	$ 160,000,000
May 2018 Amendments
Debt Instrument [Line Items]
Deferred financing costs		$ 500,000
Extended Maturity | Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 30,000,000	$ 130,000,000
Maximum borrowing capacity, maturity date not extended			$ 30,000,000

Debt Debt - Schedule of Long-Te

Debt Debt - Schedule of Long-Term Debt Instruments (Details) - Term Loans $ in Thousands	12 Months Ended
	Sep. 28, 2018USD ($)
Debt Instrument [Line Items]
Principal balance	$ 679,856
Line of credit effective interest rate	4.49%
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	2.24%
Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%

Debt - Schedule of Remained Out

Debt - Schedule of Remained Outstanding on Term Loans (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Debt Instrument [Line Items]
Unamortized deferred financing costs	$ (10,900)
Current portion	6,885	$ 6,885
Long-term, less current portion	658,372	$ 661,471
Term Loans
Debt Instrument [Line Items]
Principal balance	679,856
Unamortized discount	(4,625)
Unamortized deferred financing costs	(9,974)
Total term loans	665,257
Current portion	6,885
Long-term, less current portion	$ 658,372

Debt - Schedule of Minimum Prin

Debt - Schedule of Minimum Principal Payments under Term Loans (Detail) - Term Loans $ in Thousands	Sep. 28, 2018USD ($)
Debt Instrument [Line Items]
2,019	$ 6,885
2,020	6,885
2,021	6,885
2,022	6,885
2,023	6,885
Thereafter	645,431
Total	$ 679,856

Capital Lease and Financing O_3

Capital Lease and Financing Obligations (Details) - USD ($) $ in Thousands	Dec. 28, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Capital Leased Assets [Line Items]
Proceeds from corporate facility financing		$ 4,000	$ 0	$ 0
Discount rate		7.20%
100 Chelmsford Street
Capital Leased Assets [Line Items]
Lease term	20 years
Financing obligations associated with leased facility	$ 8,200
Proceeds from corporate facility financing	4,200
Construction allowances	$ 4,000
144 Chelmsford Street Lease
Capital Leased Assets [Line Items]
Lease term	20 years
Capital lease obligations incurred		$ 16,300	3,600
121 Hale Street
Capital Leased Assets [Line Items]
Lease term	14 years
Financing obligations associated with leased facility	$ 4,000
Corporate Facility Leases
Capital Leased Assets [Line Items]
Lease term	20 years
Financing obligations associated with leased facility		28,300	15,800
FiBest and Bin Optics
Capital Leased Assets [Line Items]
Financing obligations associated with leased facility		$ 1,200	$ 2,300

Capital Lease and Financing O_4

Capital Lease and Financing Obligations Future Minimum Lease Payments (Details) $ in Thousands	Sep. 28, 2018USD ($)
Capital Lease and Financing Obligations [Abstract]
2,019	$ 2,797
2,020	2,760
2,021	2,686
2,022	2,547
2,023	2,563
Thereafter	42,247
Total minimum capital lease payments	55,600
Less amount representing interest	(27,786)
Present value of net minimum capital lease payments	$ 27,814

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Domestic Plan | Calender Year 2017
Employee Benefit Plan [Line Items]
Discretionary matching contribution	$ 2,700,000	$ 2,400,000
Domestic Plan | Calender Year 2018
Employee Benefit Plan [Line Items]
Discretionary matching contribution	0
Domestic Plan | Calender Year 2016
Employee Benefit Plan [Line Items]
Discretionary matching contribution			$ 1,900,000
Foreign Plan
Employee Benefit Plan [Line Items]
Discretionary matching contribution	$ 1,200,000	$ 1,300,000	$ 1,100,000

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Lease Payments for Operating Leases (Detail) $ in Thousands	Sep. 28, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,019	$ 10,068
2,020	7,527
2,021	5,442
2,022	3,766
2,023	3,356
Thereafter	4,663
Total minimum lease payments	$ 34,822

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	Sep. 28, 2018	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Loss Contingencies [Line Items]
Rent expenses		$ 9.5	$ 10.9	$ 7
Asset retirement obligation	$ 1.8	1.8	$ 2.3	$ 4.3
Outstanding non-cancelable purchase commitments	1.8
Letter of Credit
Loss Contingencies [Line Items]
Outstanding unused letters of credit	$ 0.4	$ 0.4

Accrued Liabilities - Schedule

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Other Liabilities Disclosure [Abstract]
Compensation and benefits	$ 22,935	$ 32,505
Distribution costs	10,670	5,777
Product warranty	5,756	3,672
Professional fees	1,875	2,140
Rent and utilities	1,660	1,257
Contingent consideration	585	1,679
Income taxes payable	415	4,184
Purchase price holdback	375	1,000
Restructuring costs	89	627
Other	5,585	5,402
Total	$ 49,945	$ 58,243

Restructurings- Additional Deta

Restructurings- Additional Details (Details) - Ithaca, New York Production Closure $ in Millions	Sep. 28, 2018USD ($)
Minimum
Restructuring Cost and Reserve [Line Items]
Expected remaining restructuring costs	$ 5.3
Expected future cash expenditures	2.5
Maximum
Restructuring Cost and Reserve [Line Items]
Expected remaining restructuring costs	6.7
Expected future cash expenditures	3.2
One-time Termination Benefits | Minimum
Restructuring Cost and Reserve [Line Items]
Expected remaining restructuring costs	1.5
One-time Termination Benefits | Maximum
Restructuring Cost and Reserve [Line Items]
Expected remaining restructuring costs	1.9
Contract Termination | Minimum
Restructuring Cost and Reserve [Line Items]
Expected remaining restructuring costs	1
Contract Termination | Maximum
Restructuring Cost and Reserve [Line Items]
Expected remaining restructuring costs	1.3
Asset Acceleration Costs | Minimum
Restructuring Cost and Reserve [Line Items]
Expected remaining restructuring costs	2.8
Asset Acceleration Costs | Maximum
Restructuring Cost and Reserve [Line Items]
Expected remaining restructuring costs	$ 3.5

Restructurings Restructurings -

Restructurings Restructurings - Restructuring and Related Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$ 6,265	$ 2,744	$ 3,465
Employee related costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	2,789	2,744	3,465
Facility related expenses
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$ 3,476	$ 0	$ 0

Restructurings - Summary of Cos

Restructurings - Summary of Costs Related to Restructuring Actions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Restructuring Reserve [Roll Forward]
Beginning balance	$ 627	$ 3,104	$ 943
Expense	6,265	2,744	3,465
Charges paid/settled	(6,803)	(5,221)	(1,304)
Ending balance	$ 89	$ 627	$ 3,104

Product Warranties - Additional

Product Warranties - Additional Information (Detail)	12 Months Ended
	Sep. 28, 2018
Guarantees [Abstract]
Term of product warranties	12 months

Product Warranties - Schedule o

Product Warranties - Schedule of Product Warranty Liability Activity (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance — beginning of year	$ 3,672	$ 1,039	$ 656
(Divested)/acquired	(49)	952	413
Provisions/(expense)	1,865	1,737	(30)
Direct charges/(payments)	(268)	56	0
Balance — end of year	$ 5,756	$ 3,672	$ 1,039

Intangible Assets - Summary of

Intangible Assets - Summary of Amortization Expense of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Total	$ 81,694	$ 65,742	$ 50,255
Cost of revenue
Finite-Lived Intangible Assets [Line Items]
Total	33,429	30,286	26,615
Selling, general and administrative
Finite-Lived Intangible Assets [Line Items]
Total	$ 48,265	$ 35,456	$ 23,640

Intangible Assets - Summary o_2

Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Finite-Lived Intangible Assets [Line Items]
Total	$ 773,307	$ 811,703
Less accumulated amortization	(260,522)	(190,611)
Intangible assets — net	512,785	621,092
Trade name
Finite-Lived Intangible Assets [Line Items]
Total	3,400	3,400
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Total	251,673	251,655
Less accumulated amortization	(140,000)	(106,800)
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total	518,234	556,648
Less accumulated amortization	$ (120,500)	$ (83,900)

Intangible Assets - Summary o_3

Intangible Assets - Summary of Activity in Intangible Assets and Goodwill (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Goodwill and Intangible Assets [Roll Forward]
Beginning balance		$ 811,703	$ 384,471
Acquired			436,181
Placed in service			0
Fair value adjustment		0	0
Currency translation adjustments		889	(4,597)
Impairments of intangible assets			(4,352)
Ending balance	$ 811,703	773,307	811,703
In-process research and development
Goodwill and Intangible Assets [Roll Forward]
Beginning balance		0	8,000
Acquired			0
Placed in service			(3,648)
Fair value adjustment		0	0
Currency translation adjustments		0	0
Impairments of intangible assets	(4,400)		(4,352)
Ending balance	0	0	0
Trade name
Goodwill and Intangible Assets [Roll Forward]
Beginning balance		3,400	3,400
Acquired			0
Placed in service			0
Fair value adjustment		0	0
Currency translation adjustments		0	0
Impairments of intangible assets			0
Ending balance	3,400	3,400	3,400
Total Goodwill
Goodwill and Intangible Assets [Roll Forward]
Beginning balance		313,765	120,024
Acquired			195,145
Placed in service			0
Fair value adjustment		2,790	220
Currency translation adjustments		81	(1,624)
Impairments of intangible assets			0
Ending balance	313,765	314,076	313,765
Acquired technology
Goodwill and Intangible Assets [Roll Forward]
Beginning balance		251,655	165,397
Acquired			83,518
Placed in service	3,600		3,648
Fair value adjustment		0	0
Currency translation adjustments		18	(908)
Impairments of intangible assets			0
Ending balance	251,655	251,673	251,655
Customer relationships
Goodwill and Intangible Assets [Roll Forward]
Beginning balance		556,648	207,674
Acquired			352,663
Placed in service			0
Fair value adjustment		0	0
Currency translation adjustments		871	(3,689)
Impairments of intangible assets			0
Ending balance	$ 556,648	518,234	$ 556,648
LR4 | Disposal Group, Not Discontinued Operations
Goodwill and Intangible Assets [Roll Forward]
Increase (decrease) in intangible assets		(39,285)
Increase (decrease) in goodwill		(2,560)
LR4 | Disposal Group, Not Discontinued Operations | In-process research and development
Goodwill and Intangible Assets [Roll Forward]
Increase (decrease) in finite lived intangible assets		0
LR4 | Disposal Group, Not Discontinued Operations | Trade name
Goodwill and Intangible Assets [Roll Forward]
Increase (decrease) to indefinite lived intangible assets		0
LR4 | Disposal Group, Not Discontinued Operations | Acquired technology
Goodwill and Intangible Assets [Roll Forward]
Increase (decrease) in finite lived intangible assets		0
LR4 | Disposal Group, Not Discontinued Operations | Customer relationships
Goodwill and Intangible Assets [Roll Forward]
Increase (decrease) in finite lived intangible assets		$ (39,285)

Intangible Assets - Summary o_4

Intangible Assets - Summary of Estimated Amortization of Intangible Assets (Detail) $ in Thousands	Sep. 28, 2018USD ($)
Amortization expense
2,019	$ 83,749
2,020	81,669
2,021	74,061
2,022	61,830
2,023	51,466
Thereafter	$ 156,610

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 29, 2017	Jul. 01, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Impairments of intangible assets				$ (4,352)
Placed in service				0
Accumulated amortization	$ 190,611		$ 260,522	190,611
Impairment charges		$ 13,800	9,143	4,352	$ 12,955
Impairment charges			6,575	4,352	$ 11,765
Inventory impairment charges		2,000
Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Impairment charges		10,100
Fixed Assets
Finite-Lived Intangible Assets [Line Items]
Impairment charges		600
Contractual Commitments
Finite-Lived Intangible Assets [Line Items]
Impairment charges		$ 1,100
Acquired technology
Finite-Lived Intangible Assets [Line Items]
Impairments of intangible assets				0
Placed in service	3,600			3,648
Accumulated amortization	106,800		140,000	106,800
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Impairments of intangible assets				0
Placed in service				0
Accumulated amortization	83,900		$ 120,500	83,900
In-process research and development
Finite-Lived Intangible Assets [Line Items]
Impairments of intangible assets	$ (4,400)			(4,352)
Placed in service				$ (3,648)

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Sep. 29, 2017
Deferred tax assets (liabilities):
Federal and foreign net operating losses and credits	$ 321,982	$ 396,871
Intangible assets	(94,929)	(180,544)
Property and equipment	(6,293)	(1,045)
Other non-current deferred tax assets	13,850	20,756
Deferred compensation	3,810	9,291
Deferred gain	6,575	14,853
Valuation allowance	(243,112)	(274,406)
Total deferred tax (liability) asset	$ 1,883
Total deferred tax (liability) asset		$ 14,224

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Income Taxes [Line Items]
Deferred tax liability		$ 14,224
Income tax (benefit) expense	$ (21,473)	100,911	$ (17,983)
Reserve related to future rebates and returns	93,500
Valuation allowance amount	243,100	274,400
Valuation allowance change	(51,329)	140,419	(994)
Income (loss) from operations before income taxes	$ (155,235)	$ (49,505)	$ (21,571)
Effective income tax rate	13.80%	(203.80%)	83.40%
Foreign earnings repatriated	$ 202,000
Taxable foreign income	101,500
Undistributed earnings	23,600
Remeasurement of deferred taxes	2,600
Provisional income tax benefit due to change in net operating loss carryforward rules	5,700
Out of Period Adjustment
Income Taxes [Line Items]
Income tax (benefit) expense	3,900
Japan
Income Taxes [Line Items]
Deferred tax liability	100	$ 8,800
CANADA
Income Taxes [Line Items]
Valuation allowance amount	13,600
United States
Income Taxes [Line Items]
Valuation allowance change	(31,300)
Ireland
Income Taxes [Line Items]
Foreign earnings repatriated	30,300
Undistributed earnings	5,100
Grand Cayman
Income Taxes [Line Items]
Foreign earnings repatriated	70,000
Undistributed earnings	15,700
Federal
Income Taxes [Line Items]
Operating loss carryforwards	1,149,200
Applied Micro Circuits Corporation | Federal
Income Taxes [Line Items]
Operating loss carryforwards	772,700
Mindspeed Wireless Business | Federal
Income Taxes [Line Items]
Operating loss carryforwards	158,900
BinOptics Corporation | Federal
Income Taxes [Line Items]
Operating loss carryforwards	26,200
Tax Year 2015 | Out of Period Adjustment
Income Taxes [Line Items]
Income tax (benefit) expense	1,700
Tax Year 2014 | Out of Period Adjustment
Income Taxes [Line Items]
Income tax (benefit) expense	1,000
Tax Year 2013 | Out of Period Adjustment
Income Taxes [Line Items]
Income tax (benefit) expense	1,200
MACOM | Federal
Income Taxes [Line Items]
Operating loss carryforwards	$ 180,800

Income Taxes - Summary of Domes

Income Taxes - Summary of Domestic and Foreign Income (Loss) from Continuing Operations Before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
United States	$ (145,851)	$ (111,432)	$ (46,593)
Foreign	(9,384)	61,927	25,022
(Loss) income from operations before income taxes	$ (155,235)	$ (49,505)	$ (21,571)

Income Taxes - Components of Pr

Income Taxes - Components of Provision (Benefit) for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Current:
Federal	$ (6,876)	$ 100	$ (5,861)
State	(160)	225	(766)
Foreign	1,642	7,307	906
Current provision (benefit)	(5,394)	7,632	(5,721)
Deferred:
Federal	75,428	(42,637)	(8,163)
State	(15,526)	(4,037)	(502)
Foreign	(24,652)	(466)	(2,603)
Change in valuation allowance	(51,329)	140,419	(994)
Deferred provision (benefit)	(16,079)	93,279	(12,262)
Total provision (benefit)	$ (21,473)	$ 100,911	$ (17,983)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Effective Tax Rates (Detail)	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Federal statutory rate	24.50%	35.00%	35.00%
Foreign rate differential	5.10%	31.90%	40.10%
State taxes net of federal benefit	0.80%	0.20%	1.00%
Warrant liabilities	4.40%	(1.80%)	(26.70%)
Change in valuation allowance	34.00%	(270.00%)	3.00%
Research and development credits	9.00%	12.80%	16.90%
Correction of prior period	0.00%	0.00%	18.30%
Provision to return adjustments	8.30%	(4.00%)	3.50%
Nondeductible compensation expense	1.40%	(4.10%)	(9.20%)
Nondeductible legal fees	0.90%	(3.90%)	(1.80%)
2017 tax reform	(73.70%)	0.00%	0.00%
Other permanent differences	(0.90%)	0.10%	3.30%
Effective income tax rate	13.80%	(203.80%)	83.40%

Income Taxes - Activity Related

Income Taxes - Activity Related to Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Income Tax Disclosure [Abstract]
Beginning balance	$ (1,670)	$ (1,670)
Additions based on tax positions	0	0
Reductions based on tax positions	1,370	0
Ending balance	$ (300)	$ (1,670)

Share-Based Compensation Plans

Share-Based Compensation Plans - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended			24 Months Ended
	Nov. 30, 2017USD ($)$ / sharesshares	Sep. 28, 2018USD ($)trancheplan$ / sharesshares	Sep. 29, 2017USD ($)$ / sharesshares	Sep. 30, 2016USD ($)$ / sharesshares	Sep. 30, 2016shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity incentive plans | plan		3
Number of shares available for future issuance (in shares)		14,100,000
Compensation and benefits | $		$ 22,935	$ 32,505
Share-based compensation expense | $		(31,937)	(36,335)	$ (26,954)
Unrecognized compensation costs | $		$ 51,300
Weighted average period for recognition of unrecognized compensation costs		2 years 4 months 24 days
Intrinsic value of options recognized | $		$ 900	$ 8,900	3,700
Options granted (in shares)		405,000
Exercise price of options (in USD per share) | $ / shares		$ 36.58
Common stock, issued (in shares)		65,202,000	64,279,000
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant (in shares)		3,200,000
Incentive Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
ISU awards outstanding (in shares)		191,620	203,293
Compensation and benefits | $		$ 1,900	$ 4,400
ISU awards exercised (in shares)		68,813
Share-based compensation expense | $		$ (1,100)	$ (3,900)	$ (4,000)
Total fair value of restricted stock awards and units vesting | $		$ 1,400
Incentive Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	10,924
Stock Options with Performance-based Vesting Criteria
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term					7 years
Options granted (in shares)				5,000
Grant date fair value of options (in USD per share) | $ / shares				$ 10.54
Options, aggregate grant date fair value | $				$ 100
Expected volatility				31.80%
Exercise price of options (in USD per share) | $ / shares				$ 39.50
Risk-free interest rate				1.15%
Expected term (years)				4 years
Stock Options with Market-based Vesting Criteria
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term		7 years
Weighted average period for recognition of unrecognized compensation costs		3 years
Options granted (in shares)		325,000	320,000	300,000
Grant date fair value of options (in USD per share) | $ / shares		$ 15.52	$ 13.18	$ 11.65
Options, aggregate grant date fair value | $		$ 5,000	$ 4,300	$ 3,500
Expected volatility		45.80%	32.30%	36.50%
Risk-free interest rate		2.30%	1.90%	2.10%
Expected term (years)		3 years 5 months 1 day	7 years	7 years
Non Qualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	69,076
Measurement period for target price per share for recognition of remaining unamortized compensation cost		30 days
Incentive And Nonqualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period for recognition of unrecognized compensation costs	4 years 6 months
Grant date fair value of options (in USD per share) | $ / shares	$ 17.55
Options, aggregate grant date fair value | $	$ 1,400
Expected volatility	45.70%
Risk-free interest rate	2.21%
Exercise Price (in USD per share) | $ / shares	$ 36.61
Expected term (years)	6 years 6 months
Restricted Stock Awards and Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		1,145,000
Total fair value of restricted stock awards and units vesting | $		$ 19,700	$ 51,200	$ 26,500
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of vesting restricted stock units | $		$ 37,100
PRSU awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		84,753
Number of tranches | tranche		3
Employee Stock | Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum ESPP payroll deductions		15.00%
Common stock, issued (in shares)		305,851	146,149	154,187	154,187
Maximum percentage annual increase of share available for future issuance		1.25%
Annual increase of share available for future issuance (in shares)		550,000
Employee Stock | 2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage annual increase of share available for future issuance		4.00%
Annual increase of share available for future issuance (in shares)		1,900,000
Compute Business
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $			$ (800)
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term		4 years
Minimum | PRSU awards | Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Earnings percentage of targeted shares		0.00%
Minimum | PRSU awards | Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Earnings percentage of targeted shares		0.00%
Minimum | PRSU awards | Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Earnings percentage of targeted shares		0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term		7 years
Maximum | PRSU awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Earnings percentage of targeted shares		300.00%
Incremental PRSU that could vest if all performance criteria are achieved		413,916
Maximum | PRSU awards | Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Earnings percentage of targeted shares		300.00%
Maximum | PRSU awards | Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Earnings percentage of targeted shares		300.00%
Maximum | Employee Stock | Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase of share available for future issuance (in shares)		550,000
Maximum | Employee Stock | 2012 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase of share available for future issuance (in shares)		1,900,000

Share-Based Compensation Plan_2

Share-Based Compensation Plans - Effects of Stock-Based Compensation Expense Related to Stock-Based Awards to Employees and Non-Employees (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 31,937	$ 36,335	$ 26,954
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	3,869	3,189	2,150
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	13,448	10,565	6,568
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 14,620	$ 22,581	$ 18,236

Share-Based Compensation Plan_3

Share-Based Compensation Plans - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 28, 2018USD ($)$ / sharesshares
Number of Shares
Beginning balance (in shares) | shares	1,177
Granted (in shares) | shares	405
Exercised (in shares) | shares	(27)
Forfeited, canceled or expired (in shares) | shares	(147)
Ending balance (in shares) | shares	1,408
Weighted-Average Exercise Price per Share
Beginning balance (in USD per share) | $ / shares	$ 31.61
Granted (in USD per share) | $ / shares	36.58
Exercised (in USD per share) | $ / shares	2.87
Forfeited, canceled or expired (in USD per share) | $ / shares	46.29
Ending balance (in USD per share) | $ / shares	$ 32.05
Options Outstanding, Additional Disclosures
Weighted-Average Remaining Contractual Term (in Years)	4 years 11 months 5 days
Aggregate Intrinsic Value | $	$ 1,850
Options Vested and Expected to Vest
Number of shares (in shares) | shares	1,408
Weighted-Average Exercise Price Per Share (in USD per share) | $ / shares	$ 32.05
Weighted-Average Remaining Contractual Term (in Years)	4 years 11 months 5 days
Aggregate Intrinsic Value | $	$ 1,850
Options Exercisable
Number of Shares (in shares) | shares	343
Weighted-Average Exercise Price per Share (in USD per share) | $ / shares	$ 19.08
Weighted-Average Remaining Contractual Term (in Years)	3 years 9 months 7 days
Aggregate Intrinsic Value | $	$ 1,850

Share-Based Compensation Plan_4

Share-Based Compensation Plans - Weighted Average Assumptions used for Calculating Fair Value of Stock Options Granted (Detail) - $ / shares	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Stock Options with Market-based Vesting Criteria
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.30%	1.90%	2.10%
Expected term (years)	3 years 5 months 1 day	7 years	7 years
Expected volatility	45.80%	32.30%	36.50%
Target price per share of common stock for recognition of unrecognized compensation cost (in USD per share)	$ 98.99	$ 67.39	$ 64.22
Stock Options with Performance-based Vesting Criteria
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate			1.15%
Expected term (years)			4 years
Expected volatility			31.80%
Expected dividends			0.00%

Share-Based Compensation Plan_5

Share-Based Compensation Plans - Summary of Restricted Stock Awards and Units Activity (Detail) - Restricted Stock Awards and Units - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Number of Shares
Beginning balance- unvested (in shares)	1,907
Granted (in shares)	1,145
Vested (in shares)	(906)
Forfeited, canceled or expired (in shares)	(274)
Ending balance- unvested (in shares)	1,872
Weighted-Average Grant Date Fair Value
Beginning balance- unvested (in USD per share)	$ 39.20
Granted (in USD per share)	26.68
Vested (in USD per share)	35.24
Forfeited, canceled or expired (in USD per share)	34.56
Ending balance- unvested (in USD per share)	$ 34.15
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 38,452	$ 85,093

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - $ / shares	Sep. 28, 2018	Sep. 29, 2017	Mar. 31, 2012
Class of Warrant or Right [Line Items]
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, par value (in USD per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	300,000,000	300,000,000
Common stock, par value (in USD per share)	$ 0.001	$ 0.001
Common stock, subject to forfeiture (in shares)	6,100	200
Common stock warrants price per share (in USD per share)			$ 14.05
Common Stock
Class of Warrant or Right [Line Items]
Common stock warrants (in shares)			1,281,358

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Cadence | Public Company with a Common Director
Related Party Transaction [Line Items]
Expenses from transactions with related party	$ 4.1	$ 6.3

Discontinued Operations - Dives

Discontinued Operations - Divested Business (Details) - USD ($) $ in Thousands	May 10, 2018	Nov. 14, 2018	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of assets			$ 1,274	$ 215	$ 0
LR4 | Disposal Group, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of assets	$ 5,000		5,000
Gain (loss) on disposal			34,300
Inventory			13,700
Property, plant and equipment			7,600
Goodwill			2,600
Transition services expense			2,000
Scenario, Forecast | LR4 | Disposal Group, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Additional consideration expected to be received		$ 12,200
Cash consideration on sale of business		$ 17,200
Other Current Assets | LR4 | Disposal Group, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Additional consideration expected to be received			7,400
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | LR4 | Disposal Group, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Additional consideration expected to be received			4,800
Customer relationships | LR4 | Disposal Group, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets			27,700
Maximum | LR4 | Disposal Group, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transition service agreement liability			$ 2,000

Discontinued Operations - Addit

Discontinued Operations - Additional information (Detail) - USD ($)	Aug. 17, 2015	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale		$ 4,840,000	$ 35,571,000
Inventory and other current assets			1,300,000
Property and equipment			7,800,000
Goodwill and intangible assets			28,400,000
Provision for disposal costs			2,000,000
Liabilities held for sale		0	2,144,000
Compute Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration on sale of business		36,500,000
Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other income		0	7,500,000	$ 7,500,000
Gain on sale		0	18,022,000	$ 308,000
Discontinued Operations, Disposed of by Sale | Automotive Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale			$ 18,000,000
Discontinued Operations, Disposed of by Sale | Consulting Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-design advisory services period	2 years
Discontinued Operations, Disposed of by Sale | Consulting Agreement | Maximum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration on sale of business	$ 15,000,000
Consulting Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other income		$ 0
Equity Securities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Minority investment (as a percent)		20.00%
Equity Securities | Compute
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investments		$ 36,500,000
Minority investment (as a percent)		20.00%
Selling, general and administrative | Disposal Group, Not Discontinued Operations | Compute
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transition services agreement reimbursements		$ 3,600,000

Discontinued Operations - Summa

Discontinued Operations - Summary of Operating Results Through Dates of Divestiture Related to Divested Businesses (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Operating expenses:
(Loss) income from discontinued operations	$ (378)	$ (220)	$ (18)	$ (5,599)	$ (10,719)	$ (13,700)	$ 4,136	$ 1,206	$ (6,215)	$ (19,077)	$ 5,022
Cash flow from Investing Activities (2)									4,737	25,520	7,500
Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue (1)									0	660	0
Cost of revenue (1)									(596)	2,252	0
Gross (loss) profit									596	(1,592)	0
Operating expenses:
Research and development (1)									5,251	29,167	0
Selling, general and administrative (1)									1,560	13,840	0
Total operating expenses									6,811	43,007	0
(Loss) income from discontinued operations (1)									(6,215)	(44,599)	0
Other income (2)									0	7,500	7,500
Gain on sale (2)									0	18,022	308
(Loss) income before income taxes									(6,215)	(19,077)	7,808
Income tax provision (benefit)									0	0	2,786
(Loss) income from discontinued operations									(6,215)	(19,077)	5,022
Cash flow from Operating Activities (1)									(10,734)	(42,776)	0
Cash flow from Investing Activities (2)									$ 0	$ 25,522	$ 7,500

Earnings Per Share - Computatio

Earnings Per Share - Computation for Basic and Diluted Net Income (Loss) Per Share of Common Stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Numerator:
Loss from continuing operations	$ (16,116)	$ (85,210)	$ (15,466)	$ (16,970)	$ (1)	$ (13,977)	$ (134,267)	$ (2,171)	$ (133,762)	$ (150,416)	$ (3,588)
(Loss) income from discontinued operations	$ (378)	$ (220)	$ (18)	$ (5,599)	$ (10,719)	$ (13,700)	$ 4,136	$ 1,206	(6,215)	(19,077)	5,022
Net (loss) income									(139,977)	(169,493)	1,434
Warrant liability gain									(27,646)	0	0
Net (loss) income attributable to common stockholders									$ (167,623)	$ (169,493)	$ 1,434
Denominator:
Weighted average common shares outstanding-basic (in shares)									64,741,000	60,704,000	53,364,000
Dilutive effect of warrants (in shares)									569,667	0	0
Weighted average common shares outstanding-diluted (in shares)									65,311,000	60,704,000	53,364,000
Basic (loss) income per share:
Continuing operations (in USD per share)	$ (0.25)	$ (1.31)	$ (0.24)	$ (0.26)	$ 0	$ (0.22)	$ (2.21)	$ (0.04)	$ (2.07)	$ (2.48)	$ (0.07)
Discontinued operations (in USD per share)									(0.10)	(0.31)	0.09
(Loss) income per share-basic (in USD per share)									(2.16)	(2.79)	0.03
Diluted (loss) income per share:
Continuing operations (in USD per share)	$ (0.29)	$ (1.31)	$ (0.50)	$ (0.49)	$ (0.21)	$ (0.22)	$ (2.21)	$ (0.04)	(2.47)	(2.48)	(0.07)
Discontinued operations (in USD per share)									(0.10)	(0.31)	0.09
(Loss) income per share-diluted (in USD per share)									$ (2.57)	$ (2.79)	$ 0.03

Earnings Per Share - Common Equ

Earnings Per Share - Common Equivalent Shares Excluded from Calculation from Net Income Per Share (Detail) - shares	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Dilutive effect of warrants (in shares)	569,667	0	0
Antidilutive securities excluded from earnings per share (in shares)	375,940	1,877,401	1,855,049

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Additional Information (Detail) - USD ($) $ in Thousands	Jan. 26, 2017	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Unpaid amounts related to purchase of assets		$ 4,000	$ 7,600
Equity interests issued and issuable	$ 465,100	0	465,082	$ 0
Fixed assets acquired		18,400	3,600
Loss on minority equity investment		10,406	0	$ 0
Equity Securities | Compute
Business Acquisition [Line Items]
Investments		36,500
Loss on minority equity investment		10,400
Compute Business
Business Acquisition [Line Items]
Cash consideration on sale of business		36,500
Developer Funded
Business Acquisition [Line Items]
Fixed assets acquired		$ 12,700	$ 3,600

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information - Schedule of Supplemental Cash Flow Information Regarding Noncash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest	$ 29,698	$ 30,529	$ 16,335
Cash paid (refunded) for income taxes	$ 3,559	$ (3,161)	$ (373)

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Summary of Accumulated Other Comprehensive Income, Net of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 777,374	$ 462,784
Ending balance	668,675	777,374
Foreign currency translation, net of tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	3,139	9,138
Other comprehensive income	(502)	(5,999)
Ending balance	2,637	3,139
Other Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(162)	(99)
Ending balance	(449)	(162)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	2,977	9,039
Ending balance	2,188	2,977
Unrealized gain/loss on short-term investments, net of tax
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income	$ (287)	$ (63)

Geographic and Significant Cu_3

Geographic and Significant Customer Information - Summary of Different Geographic Regions (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 151,187	$ 137,872	$ 150,414	$ 130,925	$ 166,381	$ 194,555	$ 186,084	$ 151,752	$ 570,398	$ 698,772	$ 544,338
Long-lived assets	149,923				131,019				149,923	131,019
United States
Segment Reporting Information [Line Items]
Revenue									272,951	265,038	155,998
Long-lived assets	122,888				101,044				122,888	101,044
China
Segment Reporting Information [Line Items]
Revenue									159,763	206,136	201,911
Asia Pacific, excluding China
Segment Reporting Information [Line Items]
Revenue									79,581	170,826	144,872
Long-lived assets	24,702				24,945				24,702	24,945
Other Countries
Segment Reporting Information [Line Items]
Revenue									58,103	56,772	$ 41,557
Long-lived assets	$ 2,333				$ 5,030				$ 2,333	$ 5,030

Geographic and Significant Cu_4

Geographic and Significant Customer Information - Summary of Customer Concentrations as Percentage of Total Sales and Accounts Receivable (Detail) - Customer Concentration Risk	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Total Sales
Segment Reporting Information [Line Items]
Concentration risk, percentage	57.00%	52.00%	62.00%
Total Sales | Customer A
Segment Reporting Information [Line Items]
Concentration risk, percentage	13.00%	11.00%	11.00%
Total Sales | Customer B
Segment Reporting Information [Line Items]
Concentration risk, percentage	6.00%	10.00%	15.00%
Total Sales | Customer C
Segment Reporting Information [Line Items]
Concentration risk, percentage	2.00%	6.00%	12.00%
Accounts Receivable | Customer A
Segment Reporting Information [Line Items]
Concentration risk, percentage	19.00%	13.00%
Accounts Receivable | Customer D
Segment Reporting Information [Line Items]
Concentration risk, percentage	26.00%	14.00%

Geographic and Significant Cu_5

Geographic and Significant Customer Information - Additional Information (Detail)	12 Months Ended
	Sep. 28, 2018segmentcustomer	Sep. 29, 2017customer	Sep. 30, 2016customer
Segment Reporting Information [Line Items]
Number of reportable operating segments | segment	1
Total Revenue | Customer Concentration Risk
Segment Reporting Information [Line Items]
Number of major customers | customer	10	10	10
Concentration risk, percentage	57.00%	52.00%	62.00%

Quarterly Financial Data - Sche

Quarterly Financial Data - Schedule of Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 151,187	$ 137,872	$ 150,414	$ 130,925	$ 166,381	$ 194,555	$ 186,084	$ 151,752	$ 570,398	$ 698,772	$ 544,338
Gross profit	70,982	48,169	65,601	60,954	86,896	92,629	68,864	78,495	245,706	326,884	281,609
Loss from continuing operations	(16,116)	(85,210)	(15,466)	(16,970)	(1)	(13,977)	(134,267)	(2,171)	(133,762)	(150,416)	(3,588)
(Loss) income from discontinued operations	$ (378)	$ (220)	$ (18)	$ (5,599)	$ (10,719)	$ (13,700)	$ 4,136	$ 1,206	$ (6,215)	$ (19,077)	$ 5,022
Per share data
Income (loss) from continuing operations (in USD per share)	$ (0.25)	$ (1.31)	$ (0.24)	$ (0.26)	$ 0	$ (0.22)	$ (2.21)	$ (0.04)	$ (2.07)	$ (2.48)	$ (0.07)
Income (loss) from discontinued operations (in USD per share)	(0.01)	0	0	(0.09)	(0.17)	(0.21)	0.07	0.02	(0.10)	(0.31)	0.09
Per share data
Income (loss) from continuing operations (in USD per share)	(0.29)	(1.31)	(0.50)	(0.49)	(0.21)	(0.22)	(2.21)	(0.04)	(2.47)	(2.48)	(0.07)
Income (loss) from discontinued operations (in USD per share)	$ (0.01)	$ 0	$ 0	$ (0.09)	$ (0.16)	$ (0.21)	$ 0.07	$ 0.02	$ (0.10)	$ (0.31)	$ 0.09
Warrant liability gain	$ (2,800)		$ (17,000)	$ (14,600)	$ (14,000)