Finisar (FNSR) 10-Q 6 Mar 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document	9 Months Ended
	Jan. 26, 2014	Feb. 28, 2014
Entity Information [Line Items]	'	'
Entity Registrant Name	'FINISAR CORP	'
Entity Central Index Key	'0001094739	'
Current Fiscal Year End Date	'--04-27	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	26-Jan-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	96,767,546

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$374,902	$289,076
Short-term Investments	179,847	0
Accounts receivable, net of allowance for doubtful accounts of $868 at January 26, 2014 and $958 at April 28, 2013	195,442	149,612
Accounts receivable, other	24,274	16,538
Inventories	247,126	200,670
Deferred Tax Assets	27	1,224
Prepaid expenses	22,737	17,178
Total current assets	1,044,355	674,298
Property, equipment and improvements, net	247,394	201,442
Purchased intangible assets, net	10,523	14,893
Other intangible assets, net	11,453	15,564
Goodwill	90,986	90,986
Minority investments	2,041	884
Other assets	21,034	9,780
Total assets	1,427,786	1,007,847
Current liabilities:	'	'
Accounts payable	96,723	77,630
Accrued compensation	46,402	31,492
Other accrued liabilities	26,370	23,533
Deferred revenue	15,620	9,182
Short-term debt	4,230	0
Current portion of convertible debt	40,015	0
Total current liabilities	229,360	141,837
Long-term liabilities:	'	'
Convertible debt	210,029	40,015
Other non-current liabilities	11,680	13,480
Total liabilities	451,069	195,332
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Preferred stock, $0.001 par value, 5,000,000 shares authorized, no shares issued and outstanding at January 26, 2014 and April 28, 2013	0	0
Common stock, $0.001 par value, 750,000,000 shares authorized, 96,721,272 shares and 93,778,620 shares issued and outstanding at January 26, 2014 and April 28, 2013, respectively	97	94
Additional paid-in capital	2,440,849	2,350,146
Accumulated other comprehensive income	18,980	28,525
Accumulated deficit	-1,488,923	-1,571,960
Finisar Corporation stockholders' equity	971,003	806,805
Non-controlling interest	5,714	5,710
Total stockholders' equity	976,717	812,515
Total liabilities and stockholders' equity	$1,427,786	$1,007,847

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets Parenthetical (USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Allowance for doubtful accounts	$868	$958
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	96,721,272	93,778,620
Common stock, shares outstanding	96,721,272	93,778,620

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jan. 26, 2014	Jan. 27, 2013	Jan. 26, 2014	Jan. 27, 2013
Income Statement [Abstract]	'	'	'	'
Revenues	$294,018	$238,351	$850,808	$690,918
Cost of revenues	187,368	168,377	546,638	496,001
Amortization of acquired developed technology	961	1,930	3,735	5,202
Gross profit	105,689	68,044	300,435	189,715
Operating expenses:	'	'	'	'
Research and development	46,734	39,725	135,223	117,514
Sales and marketing	10,911	10,398	35,038	31,291
General and administrative	14,353	12,797	38,081	39,058
Amortization of purchased intangibles	595	1,035	1,785	2,906
Impairment of long-lived assets	0	4,886	0	4,886
Total operating expenses	72,593	68,841	210,127	195,655
Income (loss) from operations	33,096	-797	90,308	-5,940
Interest income	335	186	834	544
Interest expense	-1,663	-648	-2,582	-2,045
Other income (expense), net	-1,873	-275	-890	-295
Income (loss) before income taxes and non-controlling interest	29,895	-1,534	87,670	-7,736
Provision for income taxes	2,827	2,153	4,816	1,733
Consolidated net income (loss)	27,068	-3,687	82,854	-9,469
Adjust for net income (loss) attributable to non-controlling interest	-7	280	183	136
Net income (loss) attributable to Finisar Corporation	$27,061	($3,407)	$83,037	($9,333)
Net income (loss) per share attributable to Finisar Corporation common stockholders:	'	'	'	'
Basic (in dollars per share)	$0.28	($0.04)	$0.87	($0.10)
Diluted (in dollars per share)	$0.26	($0.04)	$0.82	($0.10)
Shares used in computing net income (loss) per share:	'	'	'	'
Basic (in shares)	96,394	93,097	95,649	92,624
Diluted (in shares)	104,361	93,097	103,491	92,624

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Jan. 26, 2014	Jan. 27, 2013	Jan. 26, 2014	Jan. 27, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Consolidated net income (loss)	$27,068	($3,687)	$82,854	($9,469)
Other comprehensive income (loss), net of tax:	'	'	'	'
Change in cumulative foreign currency translation adjustment	-8,336	558	-9,545	-1,816
Total other comprehensive income (loss), net of tax	-8,336	558	-9,545	-1,816
Total comprehensive income (loss)	18,732	-3,129	73,309	-11,285
Adjust for comprehensive income (loss) attributable to non-controlling interest, net of tax	-7	280	183	136
Comprehensive income (loss) attributable to Finisar Corporation	$18,725	($2,849)	$73,492	($11,149)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Jan. 26, 2014	Jan. 27, 2013
Operating activities	'	'
Consolidated net income (loss)	$82,854	($9,469)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:	'	'
Depreciation	44,551	39,112
Amortization	5,878	8,667
Stock-based compensation expense	29,437	26,048
(Gain) loss on sale or retirement of assets and asset disposal group	-128	25
Impairment of long-lived assets	0	4,886
Equity in earnings of equity method investment	-509	0
Amortization of discount on 0.50% Convertible Senior Notes due 2033	927	0
Changes in operating assets and liabilities:	'	'
Accounts receivable	-47,905	15,561
Inventories	-55,544	18,465
Other assets	-16,727	4,259
Deferred income taxes	1,197	1,249
Accounts payable	20,214	-7,845
Accrued compensation	13,137	-1,732
Other accrued liabilities	2,573	2,935
Deferred revenue	4,959	-689
Net cash provided by operating activities	84,914	101,472
Investing activities	'	'
Additions to property, equipment and improvements	-93,028	-65,281
Sale of minority investment	0	10,495
Net proceeds from sale of property and equipment and asset disposal group	457	194
Acquisitions, net of cash acquired	0	-20,580
Purchase of short-term investments	-179,847	0
Purchase of intangibles assets	0	-201
Net cash used in investing activities	-272,418	-75,373
Financing activities	'	'
Repayments of debt	0	-3,150
Proceeds from issuance of 0.50% Convertible Senior Notes due 2033, net of issuance costs	255,000	0
Proceeds from a bank loan	4,230	0
Proceeds from the issuance of shares under equity plans and employee stock purchase plan	14,100	7,961
Net cash provided by financing activities	273,330	4,811
Net increase in cash and cash equivalents	85,826	30,910
Cash and cash equivalents at beginning of period	289,076	234,544
Cash and cash equivalents at end of period	374,902	265,454
Supplemental disclosure of cash flow information	'	'
Cash paid for interest	1,067	1,011
Cash paid for taxes	$3,276	$1,733

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Jan. 26, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements as of January 26, 2014 and for the three and nine month periods ended January 26, 2014 and January 27, 2013 have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP") for interim financial statements and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”), and include the accounts of Finisar Corporation and its controlled subsidiaries (collectively, “Finisar” or the “Company”). Non-controlling interest represents the minority shareholders' proportionate share of the net assets and results of operations of the Company's majority-owned subsidiary. Intercompany accounts and transactions have been eliminated in consolidation. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with U.S. GAAP and pursuant to the rules and regulations of the SEC have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, the unaudited condensed consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments) necessary for a fair presentation of the Company's financial position as of January 26, 2014, its operating results for the three and nine month periods ended January 26, 2014 and January 27, 2013, and its cash flows for the nine month periods ended January 26, 2014 and January 27, 2013. Operating results for the three and nine month periods ended January 26, 2014 are not necessarily indicative of the results that may be expected for the fiscal year ending April 27, 2014. The condensed consolidated balance sheet as of April 28, 2013 has been derived from the audited consolidated financial statements as of that date but does not include all the footnotes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the fiscal year ended April 28, 2013.
	Use of Estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from these estimates.
	Segments
	The Company has one reportable segment consisting of optical subsystems and components.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Jan. 26, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	Summary of Significant Accounting Policies
	For a description of significant accounting policies, see Note 2, Summary of Significant Accounting Policies, to the consolidated financial statements included in the Company's annual report on Form 10-K for the fiscal year ended April 28, 2013. There have been no material changes to the Company's significant accounting policies since the filing of the annual report on Form 10-K.
	Pending Adoption of New Accounting Standards
	From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board ("FASB") or other standards setting bodies that are adopted by the Company as of the specified effective date. The Company believes the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position, results of operations and cash flows upon adoption.

Acquisition_of_RedC_Optical_Ne

Acquisition of Red-C Optical Networks, Inc.	9 Months Ended
	Jan. 26, 2014
Business Combinations [Abstract]	'
Acquisition of Red-C Optical Networks, Inc.	'
	Acquisition of Red-C Optical Networks, Inc.
	During the first quarter of fiscal 2013, the Company completed the acquisition of Red-C Optical Networks, Inc., ("Red-C"), a Delaware corporation, with subsidiary operations in Tel Aviv, Israel, engaged in research, development and marketing of optical amplifiers and subsystems for the wavelength division multiplexing, or WDM, sector of the optical communication market. For additional information regarding this acquisition, see Note 4, Acquisitions, to the consolidated financial statements included in the Company's annual report on Form 10-K for the fiscal year ended April 28, 2013.

Net_income_Loss_per_share

Net income (Loss) per share	9 Months Ended
	Jan. 26, 2014
Earnings Per Share [Abstract]	'
Net Income (Loss) per Share	'
	Net Income (Loss) per Share
	Basic net income (loss) per share has been computed using the weighted-average number of shares of common stock outstanding during the period. Diluted net income (loss) per share has been computed using the weighted-average number of shares of common stock and dilutive potential common shares from stock options and restricted stock units (under the treasury stock method), 5.0% Convertible Senior Notes due 2029 (on an as-if-converted basis), and 0.50% Convertible Senior Notes due 2033 (under the treasury stock method) outstanding during the period.
	The following table presents the calculation of basic and diluted net income (loss) per share:
		Three Months Ended						Nine Months Ended
	(in thousands, except per share amounts)	January 26, 2014			January 27, 2013			January 26, 2014		January 27, 2013
	Numerator:
	Net income (loss) attributable to Finisar Corporation	$	27,061		$	(3,407	)	$	83,037	$	(9,333	)
	Numerator for basic net income (loss) per share	27,061			(3,407		)	83,037		(9,333		)
	Effect of dilutive securities:
	Interest expense on 5.0% Convertible Senior Notes due 2029	539			—			1,617		—
	Numerator for diluted net income (loss) per share	$	27,600		$	(3,407	)	$	84,654	$	(9,333	)
	Denominator:
	Denominator for basic net income (loss) per share - weighted average shares	96,394			93,097			95,649		92,624
	Effect of dilutive securities:
	Stock options and restricted stock units	4,219			—			4,094		—
	5.0% Convertible Senior Notes due 2029	3,748			—			3,748		—
	Dilutive potential common shares	7,967			—			7,842		—
	Denominator for diluted net income (loss) per share	104,361			93,097			103,491		92,624
	Net income (loss) per share attributable to Finisar Corporation common stockholders:
	Basic	$	0.28		$	(0.04	)	$	0.87	$	(0.10	)
	Diluted	$	0.26		$	(0.04	)	$	0.82	$	(0.10	)
	The following table presents common shares related to potentially dilutive securities excluded from the calculation of diluted net income (loss) per share as their effect would have been anti-dilutive:
		Three Months Ended					Nine Months Ended
	(in thousands)	January 26, 2014		January 27, 2013			January 26, 2014		January 27, 2013
	Stock options and restricted stock units	664		4,215			1,073		4,597
	Conversion of 5.0% Convertible Senior Notes due 2029	—		3,748			—		3,748
	Conversion of 0.50% Convertible Senior Notes due 2033 (1)	—		—			—		—
		664		7,963			1,073		8,345
	_______________
	(1) 0.50% Convertible Senior Notes due 2033 were excluded from the calculation of diluted earnings per share under the treasury stock method since the conversion price exceeded the average market price for the Company's common stock.

Inventories

Inventories	9 Months Ended
	Jan. 26, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories consist of the following as of January 26, 2014 and April 28, 2013:
	(in thousands)	January 26, 2014		April 28, 2013
	Raw materials	$	47,624	$	44,705
	Work-in-process	118,993		95,937
	Finished goods	80,509		60,028
	Total inventories	$	247,126	$	200,670

Property_Equipment_and_Improve

Property, Equipment and Improvements	9 Months Ended
	Jan. 26, 2014
Property, Plant and Equipment [Abstract]	'
Property, Equipment and Improvements	'
	Property, Equipment and Improvements
	Property, equipment and improvements consist of the following as of January 26, 2014 and April 28, 2013:
	(in thousands)	January 26, 2014			April 28, 2013
	Land and buildings	$	46,134		$	29,834
	Computer equipment	51,328			54,868
	Office equipment, furniture and fixtures	4,420			5,373
	Machinery and equipment	399,873			352,032
	Leasehold property and improvements	35,088			32,665
	Total	536,843			474,772
	Accumulated depreciation and amortization	(289,449		)	(273,330		)
	Property, equipment and improvements (net)	$	247,394		$	201,442

Intangible_Assets

Intangible Assets	9 Months Ended
	Jan. 26, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Intangible Assets	'
	Intangible Assets
	The following table reflects intangible assets subject to amortization as of January 26, 2014 and April 28, 2013:
		January 26, 2014
		Gross Carrying		Accumulated			Net Carrying
	(in thousands)	Amount		Amortization			Amount
	Purchased technology	$	101,044	$	(90,521	)	$	10,523
	Purchased trade name	1,172		(1,172		)	—
	Purchased customer relationships	26,944		(18,002		)	8,942
	Purchased internal use software, backlog and in-process research and development	3,396		(2,164		)	1,232
	Purchased patents	1,872		(593		)	1,279
	Total	$	134,428	$	(112,452	)	$	21,976
		April 28, 2013
		Gross Carrying		Accumulated			Net Carrying
	(in thousands)	Amount		Amortization			Amount
	Purchased technology	$	101,044	$	(86,786	)	$	14,258
	Purchased trade name	2,072		(2,072		)	—
	Purchased customer relationships	31,602		(21,120		)	10,482
	Purchased internal use software, backlog and in-process research and development	3,396		(1,920		)	1,476
	Purchased patents	1,872		(429		)	1,443
	Total	$	139,986	$	(112,327	)	$	27,659
	Estimated remaining amortization expense for the next five fiscal years and thereafter is as follows (in thousands):
	Year	Amount
	2014 (remainder of year)	$	1,610
	2015	6,356
	2016	6,092
	2017	4,065
	2018	2,149
	2019 and beyond	1,704
	Total	$	21,976

Debt

Debt	9 Months Ended
	Jan. 26, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
	0.50% Convertible Senior Notes Due 2033
	In December 2013, the Company issued and sold $258.8 million in aggregate principal amount of 0.50% Convertible Senior Notes due 2033 (the "2033 Notes") at par. The terms of the notes are governed by an indenture by and between the Company and Wells Fargo Bank, National Association, as Trustee. The notes will mature on December 15, 2033, unless earlier repurchased, redeemed or converted. The notes are senior unsecured and unsubordinated obligations of the Company, and are effectively subordinated to the Company's secured indebtedness and the indebtedness and other liabilities of the Company's subsidiaries. The notes bear interest at a rate of 0.5% per year, payable semi-annually in arrears on June 15 and December 15 each year.
	Holders of the notes may convert their notes at their option prior to the close of business on the business day immediately preceding June 15, 2033 only under the following circumstances: (1) during any fiscal quarter commencing after the fiscal quarter ending on January 26, 2014 (and only during such fiscal quarter), if the last reported sale price of the Company's common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding fiscal quarter is greater than or equal to 130% of the applicable conversion price on each applicable trading day; (2) during the five business day period after any five consecutive trading day period ("measurement period"), in which the trading price per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company's common stock and the applicable conversion rate on each such trading day; or (3) upon the occurrence of specified corporate events. On or after June 15, 2033 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their notes at any time, regardless of whether any of the foregoing circumstances have occurred. The conversion rate will initially equal 33.1301 shares of common stock per $1,000 principal amount of notes (which is equivalent to an initial conversion price of approximately $30.18 per share of common stock), subject to adjustment. Upon conversion of a note, the Company will pay or deliver, as the case may be, either cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company's election, as provided in the indenture. If holders elect to convert their notes in connection with a "fundamental change" (as defined in the indenture) that occurs on or before December 22, 2018, the Company will, to the extent provided in the indenture, increase the conversion rate applicable to such notes ("make-whole feature").
	Holders will have the option to require the Company to redeem for cash any notes held by them in the event of a fundamental change at a purchase price equal to 100% of the principal amount of the notes plus accrued and unpaid interest to, but excluding, the redemption date. Holders also have the option to require the Company to redeem for cash any notes held by them on December 15, 2018, December 15, 2023 and December 15, 2028 at a redemption price equal to 100% of the principal amount of the notes plus accrued and unpaid interest to, but excluding, the redemption date. The Company may redeem the notes in whole or in part at any time on or after December 22, 2018 at 100% of the principal amount, plus accrued and unpaid interest to, but excluding, the redemption date.
	The Company considered the features embedded in the notes, that is, the conversion feature, the holders' put feature, the Company's call feature, and the make-whole feature, and concluded that they are not required to be bifurcated and accounted for separately from the host debt instrument.
	Because of its option to settle conversion of the notes in cash, the Company separated the liability and equity components of the notes. The carrying amount of the liability component at issuance date of $209.1 million was calculated by estimating the fair value of similar liabilities without a conversion feature. The residual principal amount of the notes of $49.6 million was allocated to the equity component. The resulting debt discount is amortized as interest expense. As of January 26, 2014, the remaining debt discount amortization period was 58 months.
	The notes consisted of the following:
		As of
	(in thousands)	January 26, 2014
	Liability component:
	Principal	$	258,750
	Unamortized debt discount	(48,721		)
	Net carrying amount of the liability component	$	210,029
	Carrying amount of the equity component	$	49,648
	The Company incurred approximately $3.8 million in transaction costs in connection with the issuance of the notes. These costs were allocated to the liability and equity components in proportion to the allocation of proceeds. Transaction costs of $3.1 million, allocated to the liability component, were recognized as a non-current asset and are amortized. Transaction costs of $725,000, allocated to the equity component, were recognized as a reduction of additional paid-in capital.
	The following table sets forth interest expense information related to the notes:
		Three and Nine Months Ended
	(in thousands, except percentages)	January 26, 2014
	Contractual interest expense	$	135
	Amortization of the debt discount	927
	Amortization of issuance costs	24
	Total interest cost	$	1,086
	Effective interest rate on the liability component	4.87		%
	The Company applies the treasury stock method to determine the potential dilutive effect of the 2033 Notes on net income per share as a result of the Company's intent and stated policy to settle the principal amount of the Notes in cash.
	Korean Bank Loan
	During the second quarter of fiscal 2014, the Company's Korean subsidiary entered into a loan agreement with a Korean bank. Under this agreement, the subsidiary borrowed a total of $4.2 million at an interest rate of 4.17% per annum. The interest is payable monthly and the principal is payable in September 2014. The loan is secured by the subsidiary's fixed assets.
	5.0% Convertible Senior Notes Due 2029
	The terms of the Company's 5.0% Convertible Senior Notes due 2029 (the "2029 Notes") include a provision that allows the holders to require the Company to redeem, for cash, any of their notes on October 15, 2014 at a redemption price equal to 100% of the principal amount of the notes being redeemed, plus accrued and unpaid interest up to, but excluding, the redemption date. Accordingly, all $40.0 million of the 2029 Notes principal amount outstanding as of January 26, 2014 was classified as a current liability as of that date.

Investments_Investments

Investments Investments	9 Months Ended
	Jan. 26, 2014
Investments [Abstract]	'
Investment [Text Block]	'
	9. Investments
	Fixed Income Securities
	The Company's portfolio of fixed income securities consists of commercial paper notes and term bank certificates of deposit. All of the Company's investments in fixed income securities have original maturity (maturity at the purchase date) of less than 12 months. Investments with original maturities of three months or less are classified as cash equivalents. All of the Company's investments in fixed income securities are classified as held-to-maturity since the Company has the positive intent and ability to hold these investments until maturity. These investments are carried at amortized cost.
	The Company's investments in fixed income securities as of January 26, 2014 and April 28, 2013 were as follows:
		January 26, 2014								April 28, 2013
				Gross Unrealized								Gross Unrealized
	(in thousands)	Amortized Cost		Gains		Losses		Fair Value		Amortized Cost		Gains		Losses		Fair Value
	Commercial paper	$	119,835	$	—	$	—	$	119,835	$	—	$	—	$	—	$	—
	Certificates of deposit	120,000		—		—		120,000		—		—		—		—
	Total	$	239,835	$	—	$	—	$	239,835	$	—	$	—	$	—	$	—
	Reported as:
	Cash equivalents	$	59,988	$	—	$	—	$	59,988	$	—	$	—	$	—	$	—
	Short-term investments	179,847		—		—		179,847		—		—		—		—
	Total	$	239,835	$	—	$	—	$	239,835	$	—	$	—	$	—	$	—
	The Company monitors its investment portfolio for impairment on a periodic basis. In order to determine whether a decline in fair value is other-than-temporary, the Company evaluates, among other factors: the duration and extent to which the fair value has been less than the carrying value; the Company's financial condition and business outlook, including key operational and cash flow metrics, current market conditions and future trends in its industry; the Company's relative competitive position within the industry; and the Company's intent and ability to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value. A decline in the fair value of the security below amortized cost that is deemed other-than-temporary is charged to earnings, resulting in the establishment of a new cost basis for the affected securities. During the three and nine month periods ended January 26, 2014 and January 27, 2013 there were no realized gains or losses, and the Company did not recognize any other-than-temporary impairments.
	Minority Investments
	Included in minority investments at both January 26, 2014 and April 28, 2013 is $884,000 representing the carrying value of the Company's minority investment in one privately held company accounted for under the cost method. Additionally, included in minority investments is $1,157,000 and $0 at January 26, 2014 and April 28, 2013, respectively, representing the carrying value of the Company's minority investment in one privately held company accounted for under the equity method. At January 26, 2014, the Company had a 19.9% ownership interest in this company. For the three and nine month periods ended January 26, 2014, the Company recorded income of $200,000 and $509,000, respectively, representing its share of the net income of this minority investee, which was included in other income (expense), net in the accompanying condensed consolidated statements of operations.

Warranty

Warranty	9 Months Ended
	Jan. 26, 2014
Product Warranties Disclosures [Abstract]	'
Warranty	'
	Warranty
	The Company generally offers a one-year limited warranty for its products. The specific terms and conditions of these warranties vary depending upon the product sold. The Company estimates the costs that may be incurred under its basic limited warranty and records a liability for the amount of such costs at the time revenue is recognized. Factors that affect the Company's warranty liability include the historical and anticipated rates of warranty claims and cost to repair. The Company periodically assesses the adequacy of its recorded warranty liabilities and adjusts the amounts as necessary.
	Changes in the Company's warranty liability during the following period were as follows:
		Nine Months Ended
	(in thousands)	January 26, 2014
	Beginning balance at April 28, 2013	$	4,155
	Additions during the period based on product sold	4,618
	Change in estimate	(1,699		)
	Settlements and expirations	(1,875		)
	Ending balance at January 26, 2014	$	5,199

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	9 Months Ended
	Jan. 26, 2014
Fair Value Disclosures [Abstract]	'
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments
	The Company's financial instruments measured at fair value on a recurring basis as of January 26, 2014 and April 28, 2013 were as follows:
		January 26, 2014										April 28, 2013
		Carrying		Fair Value								Carrying		Fair Value
	(in thousands)	Amount		Level 1		Level 2		Level 3		Total		Amount		Level 1		Level 2		Level 3		Total
	Money market funds	$	15,324	$	15,324	$	—	$	—	$	15,324	$	—	$	—	$	—	$	—	$	—
	Commercial paper	119,835		—		119,835		—		119,835		—		—		—		—		—
	Certificates of deposit	120,000		—		120,000		—		120,000		—		—		—		—		—
	Total	$	255,159	$	15,324	$	239,835	$	—	$	255,159	$	—	$	—	$	—	$	—	$	—
	The Company's Level 2 financial instruments in the table above are valued using quoted market prices for similar instruments or non-binding market prices that are corroborated by observable market data.
	The Company has not estimated the fair value of its minority investments in two privately held companies as it is not practicable to estimate the fair value of these investments because of the lack of quoted market prices and the inability to estimate fair value without incurring excessive costs. As of January 26, 2014, the carrying value of the Company's minority investments in these privately held companies was $2.0 million, which management believes is not impaired.
	The Company's financial instruments not measured at fair value on a recurring basis as of January 26, 2014 and April 28, 2013 were as follows:
		January 26, 2014										April 28, 2013
		Carrying		Fair Value								Carrying		Fair Value
	(in thousands)	Amount		Level 1		Level 2		Level 3		Total		Amount		Level 1		Level 2		Level 3		Total
	2029 Notes	$	40,015	$	86,720	$	—	$	—	$	86,720	$	40,015	$	59,931	$	—	$	—	$	59,931
	2033 Notes	258,750		268,923		—		—		268,923		—		—		—		—		—
	Short-term debt	4,230		—		4,230		—		4,230		—		—		—		—		—
	Total	$	302,995	$	355,643	$	4,230	$	—	$	359,873	$	40,015	$	59,931	$	—	$	—	$	59,931
	The fair value of the 2029 Notes and 2033 Notes is based on the market price in the open market as of or close to the respective dates. The difference between the carrying value and the fair value is primarily due to the spread between the conversion price and the market value of the shares underlying the conversion.
	The fair value of short-term debt is estimated by discounting the contractual cash flows at the current interest rates charged for similar debt instruments.

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Jan. 26, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stockholders' Equity	'
	Stockholders' Equity
	The Company's share-based compensation expense was recorded in the following cost and expense categories:
		Three Months Ended						Nine Months Ended
	(in thousands)	January 26, 2014			January 27, 2013			January 26, 2014		January 27, 2013
	Cost of revenues	$	2,140		$	1,992		$	6,163	$	5,058
	Research and development	3,760			2,401			10,866		8,323
	Sales and marketing	1,310			830			3,741		2,786
	General and administrative	2,558			2,167			7,509		7,814
	Total	$	9,768		$	7,390		$	28,279	$	23,981
	The number of shares of common stock issued or becoming vested under the Company's stock compensation plans was as follows:
		Three Months Ended					Nine Months Ended
		January 26, 2014		January 27, 2013			January 26, 2014		January 27, 2013
	Employee stock purchase plan	268,289		237,832			608,946		577,136
	Exercises of stock options	108,921		64,262			633,665		176,806
	Restricted stock units vesting	144,360		107,676			1,618,326		1,141,107
	As of January 26, 2014, total compensation expense, net of estimated forfeitures, related to unvested stock options and unvested restricted stock units not yet recognized was approximately $71.6 million, which is expected to be recognized in the Company's operating results over a weighted average period of 31 months.
	The total share-based compensation capitalized as part of inventory as of January 26, 2014 was $2.0 million.

Income_Taxes

Income Taxes	9 Months Ended
	Jan. 26, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The Company recorded provisions for income taxes of $2.8 million and $2.2 million, respectively, for the three month periods ended January 26, 2014 and January 27, 2013 and $4.8 million and $1.7 million, respectively, for the nine month periods ended January 26, 2014 and January 27, 2013. The income tax provisions for the three and nine month periods ended January 26, 2014 and January 27, 2013 include state taxes and foreign income taxes arising in certain foreign jurisdictions in which the Company conducts business.
	The Company records a valuation allowance against its deferred tax assets for each period in which management concludes that it is more likely than not that the deferred tax assets will not be realized. Realization of the Company's net deferred tax assets is dependent upon future taxable income, the amount and timing of which are uncertain. Due to U.S. operating losses in previous years and continuing U.S. earnings volatility, management has established and maintained a full valuation allowance for the U.S. deferred tax assets, which comprise approximately 94% of total deferred tax assets as of January 26, 2014, which management does not believe are more likely than not to be realized in future periods.
	Utilization of the Company's net operating loss and tax credit carryforwards may be subject to a substantial annual limitation due to the ownership change limitations set forth by Internal Revenue Code Sections 382 and 383 and similar state provisions. Such an annual limitation could result in the expiration of the net operating loss and tax credit carryforwards before full utilization.

Pending_Litigation

Pending Litigation	9 Months Ended
	Jan. 26, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Pending Litigation	'
	Pending Litigation
	The Company is a party to several pending legal proceedings described below. In each of these proceedings in which the Company is a defendant, the Company believes that it has strong defenses and intends to vigorously defend the action. As of the date of this report, the Company does not believe it is reasonably possible that losses related to any of these cases have been incurred in excess of the amounts, if any, that have been accrued as of January 26, 2014. However, the litigation process is inherently uncertain, and accordingly, the Company cannot predict the outcome of any of these matters with certainty. Future developments in one or more of these matters may cause the Company to revise its estimates and related accruals in future periods.
	Class Action and Shareholder Derivative Litigation
	March 8, 2011 Earnings Announcement Cases
	Several securities class action lawsuits related to the Company's March 8, 2011 earnings announcement alleging claims under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 have been filed in the United States District Court for the Northern District of California on behalf of a purported class of persons who purchased stock between December 1 or 2, 2010 through March 8, 2011. The named defendants are the Company and its Chairman of the Board, Chief Executive Officer and Chief Financial Officer. To date, no specific amount of damages have been alleged. The cases were consolidated, lead plaintiffs were appointed and a consolidated complaint was filed. The Company filed a motion to dismiss the case. On January 16, 2013, the District Court granted the Company's motion to dismiss and granted the lead plaintiffs leave to amend the consolidated complaint. An amended consolidated complaint was filed on February 6, 2013. Thereafter, the Company filed a renewed motion to dismiss the case. On September 30, 2013, the District Court granted the Company's motion and dismissed the case with prejudice. On October 25, 2013, the lead plaintiffs filed a notice of appeal of the District Court's dismissal ruling, and the appeal is pending.
	In addition, two purported shareholder derivative lawsuits related to the Company's March 8, 2011 earnings announcement have been filed in the California Superior Court for the County of Santa Clara, and a third derivative lawsuit has been filed in the United States District Court for the Northern District of California. The complaints assert claims for alleged breach of fiduciary duty, unjust enrichment, and waste on behalf of the Company. Named as defendants are the members of the Company's board of directors, including the Company's Chairman of the Board and Chief Executive Officer, and its Chief Financial Officer. No specific amount of damages has been alleged and, by the derivative nature of the lawsuits, no damages will be alleged, against the Company. The state court cases have been consolidated and a lead plaintiff has been appointed to file a consolidated complaint. The derivative cases were stayed pending a ruling in the federal class action case. Following the September 30 ruling dismissing the class action case, the derivative cases remain stayed, subject to the right of the parties to reinstate them.
	Stock Option Cases
	On November 30, 2006, the Company announced that it had undertaken a voluntary review of its historical stock option grant practices subsequent to its initial public offering in November 1999. The review was initiated by senior management, and preliminary results of the review were discussed with the Audit Committee of the Company's board of directors. Based on the preliminary results of the review, senior management concluded, and the Audit Committee agreed, that it was likely that the measurement dates for certain stock option grants differed from the recorded grant dates for such awards and that the Company would likely need to restate its historical financial statements to record non-cash charges for compensation expense relating to some past stock option grants. The Audit Committee thereafter conducted a further investigation and engaged independent legal counsel and financial advisors to assist in that investigation. The Audit Committee concluded that measurement dates for certain option grants differed from the recorded grant dates for such awards. The Company's management, in conjunction with the Audit Committee, conducted a further review to finalize revised measurement dates and determine the appropriate accounting adjustments to its historical financial statements. The announcement of the investigation resulted in delays in filing the Company's quarterly reports on Form 10-Q for the quarters ended October 29, 2006, January 28, 2007, and January 27, 2008, and the Company's annual report on Form 10-K for the fiscal year ended April 30, 2007. On December 4, 2007, the Company filed all four of these reports which included revised financial statements.
	Following the Company's announcement on November 30, 2006 that the Audit Committee of the board of directors had voluntarily commenced an investigation of the Company's historical stock option grant practices, the Company was named as a nominal defendant in several shareholder derivative cases. These cases were consolidated into two proceedings in federal and state courts in California. The federal court cases were consolidated in the United States District Court for the Northern District of California. The state court cases were consolidated in the Superior Court of California for the County of Santa Clara. The plaintiffs in all cases alleged that certain of the Company's current or former officers and directors caused the Company to grant stock options at less than fair market value, contrary to the Company's public statements (including its financial statements), and that, as a result, those officers and directors were liable to the Company. No specific amount of damages was alleged, and by the nature of the lawsuits, no damages could be alleged against the Company. The state court action was stayed pending resolution of the consolidated federal court action. On June 12, 2007, the plaintiffs in the federal court case filed an amended complaint to reflect the results of the stock option investigation announced by the Audit Committee in June 2007. On August 28, 2007, the Company and the individual defendants filed motions to dismiss the complaint. On January 11, 2008, the Court granted the motions to dismiss, with leave to amend. On May 12, 2008, the plaintiffs filed an amended complaint. The Company and the individual defendants filed motions to dismiss the amended complaint on July 1, 2008. The Court granted the motions to dismiss on September 22, 2009, and entered judgment in favor of the defendants. The plaintiffs appealed the judgment to the United States Court of Appeals for the Ninth Circuit. On April 26, 2011, a panel of the Ninth Circuit reversed the District Court ruling and remanded the case to the District Court for further proceedings. The individual defendants filed additional motions to dismiss the case in the District Court. On July 12, 2012, the District Court issued an order granting the motion as to certain claims and individual defendants, with leave to amend except as to certain defendants, and denying the motion as to other claims and individual defendants.
	On June 27, 2013, the parties, through their respective counsel, executed a stipulation of settlement and related documents formalizing a settlement agreement that covers all of the above-referenced federal and state cases. The stipulation of settlement provided that, subject to approval by the District Court, the Company would be entitled to receive payments totaling $12.5 million from its insurance carriers and $250,000 from certain individual defendants and would be obligated to make a payment of $6.3 million to plaintiffs' counsel. In addition, under the terms of the settlement, the insurers would release any rights to recoup approximately $3.0 million previously advanced for defense costs. On August 9, 2013, the District Court issued an order preliminarily approving the proposed settlement. Following the District Court's preliminary approval, the Company assessed the likelihood of final approval as probable, and accordingly, recognized the recovery of previously incurred direct costs related to the litigation of $12.75 million as an offset to general and administrative expenses and a charge of $6.3 million for the payment to plaintiffs' counsel as general and administrative expense in the first quarter of fiscal 2014. On October 18, 2013, the District Court granted final approval of the settlement. Thereafter, the payments to the Company and plaintiffs' counsel were made in accordance with the terms of the stipulation of settlement.
	Cheetah Omni Litigation
	Customer Texas Litigation
	On July 29, 2011, Cheetah Omni LLC filed a complaint for patent infringement in the United States District Court for the Eastern District of Texas against Alcatel-Lucent USA Inc., Alcatel-Lucent Holdings, Inc., Ciena Corporation, Ciena Communications, Inc., Fujitsu Network Communications, Inc., Tellabs, Inc., Tellabs Operations, Inc., Tellabs North America, Inc., Nokia Siemens Networks US LLC, Huawei Technologies USA, Inc. and Huawei Device USA, Inc. Finisar was not named as a defendant in the lawsuit. However, the named defendants or entities affiliated with them are Finisar customers. The complaint alleges that certain ROADM products of the named defendants infringe one or more of seven Cheetah Omni patents. With respect to two of the seven patents, the Company understands Cheetah Omni to be asserting infringement by the customer defendants making, using, offering for sale, selling, and/or importing into the United States certain ROADM products that include a Finisar wavelength selective switch (WSS). Finisar has no specific information regarding whether the claims of infringement with respect to the remaining five asserted Cheetah Omni patents implicate any Finisar products.
	Finisar has received a request for indemnification from all six customer defendants with respect to the two patents mentioned above. The Company is currently evaluating the requests for indemnification. On November 19, 2012, the United States District Court in the Finisar Michigan litigation described below issued an order enjoining Cheetah Omni from continuing to pursue its claims against Finisar customers in the Texas litigation with respect to the two patents asserted against products containing a Finisar WSS. As a result, these Texas claims have been stayed pending the outcome of the Michigan litigation. If such a stay is later lifted, the Company expects that the defendant customers will defend the lawsuit vigorously at least with respect to the claims that implicate any Finisar products. However, there can be no assurance that they will be successful in their defense and, if they are not successful with respect to the two patents mentioned above, Finisar may be liable to indemnify the accused customers for significant costs and damages. Even if the defense is successful, the Company may incur substantial legal fees and other costs in defending and/or aiding in the defense of the lawsuit with respect to the two patents mentioned above. Further, the lawsuit could divert the efforts and attention of the Company's management and technical personnel, which could harm its business.
	Finisar Michigan Litigation
	On December 23, 2011, the Company filed a declaratory judgment action in the United States District Court for the Eastern District of Michigan seeking a declaration of invalidity and non-infringement by Finisar and its customers of four Cheetah Omni patents, including the two patents implicating the Company's WSS that are asserted against Finisar customers in the case described above that is currently pending in the Eastern District of Texas. On February 27, 2012, Cheetah Omni filed its answer to the complaint in which it denied the allegations of invalidity with respect to the four patents at issue.  However, in its initial answer Cheetah Omni did not deny any of the allegations of non-infringement in the Company's complaint.  Cheetah Omni also did not include any counterclaims.  Before Cheetah Omni's answer was filed, on February 24, 2012, the Company filed a motion seeking to enjoin Cheetah Omni's pending claims implicating the Company's WSS asserted against the Company's customers in the Eastern District of Texas case described above and for leave to file a motion for summary judgment of non-infringement. This motion with respect to the requested injunction was granted on November 19, 2012 as described above with respect to the customer Michigan litigation. The motion for leave to file a motion for summary judgment has been denied pending completion of claim construction. After Cheetah Omni's answer was filed, the Company filed a motion for judgment on the pleadings in favor of the Company, and Cheetah Omni filed a motion requesting permission to add counterclaims of infringement by the Company's WSS devices. The motion for judgment on the pleadings was denied. The motion for permission to add counterclaims of infringement was granted, and Cheetah Omni thereafter added claims accusing the Company's WSS devices of infringement of the two Cheetah Omni patents. The Company intends to defend the counterclaims vigorously. However, there can be no assurance that the defense will be successful and, if the defense is not successful, Finisar may be liable for substantial damages, including possible indemnification obligations to the Company's customers. Even if the defense is successful, the Company may incur substantial legal fees and other costs in defending the counterclaims. Further, the lawsuit could divert the efforts and attention of the Company's management and technical personnel, which could harm its business.
	Thomas Swan Litigation
	On February 26, 2013, Thomas Swan & Co. Ltd. filed a complaint for patent infringement in the United States District Court for the Eastern District of Texas against the Company. The complaint alleges that Finisar's WSS products, ROADM line cards containing a Finisar WSS, and Waveshaper products infringe four related Thomas Swan patents. The Company's customer, Fujitsu Network Communications, has been added as a co-defendant in this lawsuit. The Company has performed a review of the asserted patents and believes that the patent claims are not infringed and/or are invalid. The Company intends to defend this lawsuit vigorously. However, there can be no assurance that the defense will be successful and, if the defense is not successful, Finisar may be liable for substantial damages, including possible indemnification obligations to the Company's customers. Even if the defense is successful, the Company may incur substantial legal fees and other costs in defending the lawsuit. Further, the lawsuit could divert the efforts and attention of the Company's management and technical personnel, which could harm its business. Trial in this case has been scheduled for February 2, 2015.
	Mears Technologies Litigation
	On May 6, 2013, Mears Technologies, Inc. filed a complaint for patent infringement in the United States District Court for the Eastern District of Texas against the Company. The complaint alleges that Finisar's WSS products, ROADM line cards containing a Finisar WSS, and Waveshaper products infringe a Mears Technologies patent. The Company has performed an initial review of the asserted patent and believes that the patent claims are not infringed and/or are invalid. The Company intends to defend this lawsuit vigorously. However, there can be no assurance that the defense will be successful and, if the defense is not successful, Finisar may be liable for substantial damages, including possible indemnification obligations to the Company's customers. Even if the defense is successful, the Company may incur substantial legal fees and other costs in defending the lawsuit. Further, the lawsuit could divert the efforts and attention of the Company's management and technical personnel, which could harm its business. Trial in this case has been scheduled for December 1, 2014.
	Other
	In the ordinary course of business, the Company is a party to litigation, claims and assessments in addition to those described above. Based on information currently available, management does not believe the impact of these other matters will have a material adverse effect on its business, financial condition, results of operations or cash flows of the Company.

Guarantees_and_Indemnification

Guarantees and Indemnifications	9 Months Ended
	Jan. 26, 2014
Guarantees [Abstract]	'
Guarantees and Indemnifications	'
	Guarantees and Indemnifications
	Upon issuance of a guarantee, the guarantor must recognize a liability for the fair value of the obligations it assumes under that guarantee. As permitted under Delaware law and in accordance with the Company's Bylaws, the Company indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company's request in such capacity. The term of the indemnification period is for the officer's or director's lifetime. The Company may terminate the indemnification agreements with its officers and directors upon 90 days written notice, but termination will not affect claims for indemnification relating to events occurring prior to the effective date of termination. The maximum amount of potential future indemnification is unlimited; however, the Company has a director and officer liability insurance policy that may enable it to recover a portion of any future amounts paid.
	The Company enters into indemnification obligations under its agreements with other companies in its ordinary course of business, including agreements with customers, business partners and insurers. Under these provisions the Company generally indemnifies and holds harmless the indemnified party for losses suffered or incurred by the indemnified party as a result of the Company's activities or the use of the Company's products. These indemnification provisions generally survive termination of the underlying agreement. In some cases, the maximum potential amount of future payments the Company could be required to make under these indemnification provisions is unlimited.
	The Company believes the fair value of these indemnification obligations is immaterial. Accordingly, the Company has not recorded any liabilities for these agreements as of January 26, 2014. To date, the Company has not incurred material costs to defend lawsuits or settle claims related to these indemnification agreements.

Related_Party_Transaction

Related Party Transaction	9 Months Ended
	Jan. 26, 2014
Related Party Transactions [Abstract]	'
Related Parties	'
	Related Parties
	During the three and nine month periods ended January 26, 2014, the Company paid $46,004 and $152,082, respectively, in cash compensation to a company owned by Guy Gertel, the brother of the Chief Executive Officer of the Company, for sales and marketing services. In addition, during the first quarter of fiscal 2014, the Company granted to Mr. Gertel, for no additional consideration, 4,164 restricted stock units with a fair market value of $66,957, which vest as follows: 25% on June 24, 2014 and an additional 25% on each of the next three anniversaries thereafter, to be fully vested on June 24, 2017, subject to him continuing to provide services to Finisar.
	During the three and nine month periods ended January 27, 2013, the Company paid $50,466 and $152,690, respectively, in cash compensation to Mr. Gertel's company. In addition, during the first quarter of fiscal 2013, the Company granted to Mr. Gertel, for no additional consideration, 3,814 restricted stock units with a fair market value of $49,086, which vest as follows: 25% on June 14, 2013 and an additional 25% on each of the next three anniversaries thereafter, to be fully vested on June 14, 2016, subject to him continuing to provide services to Finisar.
	Amounts paid to Mr. Gertel represented values considered by management to be fair and reasonable, reflective of an arm's length transaction.

Subsequent_Event_Subsequent_Ev

Subsequent Event Subsequent Event (Notes)	9 Months Ended
	Jan. 26, 2014
Subsequent Events [Abstract]	'
Subsequent Events [Text Block]	'
	Subsequent Event
	On January 31, 2014, the Company acquired all outstanding equity interests in u2t Photonics AG (“u2t”), a German company engaged in research, development and marketing of optical components for high-speed telecom applications, for approximately $20 million in cash, subject to certain adjustments. With this transaction, the Company will add u2t's Indium-Phosphide (“InP”) -based 100 Gbps high speed receivers and photodetectors to its existing portfolio of high speed optics technologies. In addition, this acquisition will consolidate the Company’s previously announced partnership with u2t on InP-based IQ Mach-Zehnder modulators for 100 Gbps coherent applications. These receiver, photodiode and modulator technologies and products, when combined with the Company’s narrow-line width tunable lasers, will provide a full suite of optical components and enable the Company to offer its customers vertically integrated modules for the 100 Gbps coherent metro and long haul markets. Due to the timing of closing, the Company has not yet finalized its accounting for this acquisition. Accordingly, financial statement disclosures otherwise required by ASC 805 for business combinations have not been presented herein.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Jan. 26, 2014
Accounting Policies [Abstract]	'
Consolidation, Policy [Policy Text Block]	'
	The accompanying unaudited condensed consolidated financial statements as of January 26, 2014 and for the three and nine month periods ended January 26, 2014 and January 27, 2013 have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP") for interim financial statements and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”), and include the accounts of Finisar Corporation and its controlled subsidiaries (collectively, “Finisar” or the “Company”). Non-controlling interest represents the minority shareholders' proportionate share of the net assets and results of operations of the Company's majority-owned subsidiary. Intercompany accounts and transactions have been eliminated in consolidation. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with U.S. GAAP and pursuant to the rules and regulations of the SEC have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, the unaudited condensed consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments) necessary for a fair presentation of the Company's financial position as of January 26, 2014, its operating results for the three and nine month periods ended January 26, 2014 and January 27, 2013, and its cash flows for the nine month periods ended January 26, 2014 and January 27, 2013.
Use of Estimates, Policy [Policy Text Block]	'
	Use of Estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from these estimates.
Segments, Policy [Policy Text Block]	'
	Segments
	The Company has one reportable segment consisting of optical subsystems and components.
Earnings Per Share, Policy [Policy Text Block]	'
	Basic net income (loss) per share has been computed using the weighted-average number of shares of common stock outstanding during the period. Diluted net income (loss) per share has been computed using the weighted-average number of shares of common stock and dilutive potential common shares from stock options and restricted stock units (under the treasury stock method), 5.0% Convertible Senior Notes due 2029 (on an as-if-converted basis), and 0.50% Convertible Senior Notes due 2033 (under the treasury stock method) outstanding during the period.
Standard Product Warranty, Policy [Policy Text Block]	'
	The Company generally offers a one-year limited warranty for its products. The specific terms and conditions of these warranties vary depending upon the product sold. The Company estimates the costs that may be incurred under its basic limited warranty and records a liability for the amount of such costs at the time revenue is recognized. Factors that affect the Company's warranty liability include the historical and anticipated rates of warranty claims and cost to repair. The Company periodically assesses the adequacy of its recorded warranty liabilities and adjusts the amounts as necessary.
Income Tax, Policy [Policy Text Block]	'
	The Company records a valuation allowance against its deferred tax assets for each period in which management concludes that it is more likely than not that the deferred tax assets will not be realized. Realization of the Company's net deferred tax assets is dependent upon future taxable income, the amount and timing of which are uncertain. Due to U.S. operating losses in previous years and continuing U.S. earnings volatility, management has established and maintained a full valuation allowance for the U.S. deferred tax assets, which comprise approximately 94% of total deferred tax assets as of January 26, 2014, which management does not believe are more likely than not to be realized in future periods.

Net_income_loss_per_share_Tabl

Net income (loss) per share (Tables)	9 Months Ended
	Jan. 26, 2014
Earnings Per Share [Abstract]	'
Schedule of Calculation of Numerator and Denominator in Earnings Per Share [Table Text Block]	'
	The following table presents the calculation of basic and diluted net income (loss) per share:
		Three Months Ended						Nine Months Ended
	(in thousands, except per share amounts)	January 26, 2014			January 27, 2013			January 26, 2014		January 27, 2013
	Numerator:
	Net income (loss) attributable to Finisar Corporation	$	27,061		$	(3,407	)	$	83,037	$	(9,333	)
	Numerator for basic net income (loss) per share	27,061			(3,407		)	83,037		(9,333		)
	Effect of dilutive securities:
	Interest expense on 5.0% Convertible Senior Notes due 2029	539			—			1,617		—
	Numerator for diluted net income (loss) per share	$	27,600		$	(3,407	)	$	84,654	$	(9,333	)
	Denominator:
	Denominator for basic net income (loss) per share - weighted average shares	96,394			93,097			95,649		92,624
	Effect of dilutive securities:
	Stock options and restricted stock units	4,219			—			4,094		—
	5.0% Convertible Senior Notes due 2029	3,748			—			3,748		—
	Dilutive potential common shares	7,967			—			7,842		—
	Denominator for diluted net income (loss) per share	104,361			93,097			103,491		92,624
	Net income (loss) per share attributable to Finisar Corporation common stockholders:
	Basic	$	0.28		$	(0.04	)	$	0.87	$	(0.10	)
	Diluted	$	0.26		$	(0.04	)	$	0.82	$	(0.10	)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	'
	The following table presents common shares related to potentially dilutive securities excluded from the calculation of diluted net income (loss) per share as their effect would have been anti-dilutive:
		Three Months Ended					Nine Months Ended
	(in thousands)	January 26, 2014		January 27, 2013			January 26, 2014		January 27, 2013
	Stock options and restricted stock units	664		4,215			1,073		4,597
	Conversion of 5.0% Convertible Senior Notes due 2029	—		3,748			—		3,748
	Conversion of 0.50% Convertible Senior Notes due 2033 (1)	—		—			—		—
		664		7,963			1,073		8,345

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Jan. 26, 2014
Inventory Disclosure [Abstract]	'
Schedule of Inventory, Current [Table Text Block]	'
	Inventories consist of the following as of January 26, 2014 and April 28, 2013:
	(in thousands)	January 26, 2014		April 28, 2013
	Raw materials	$	47,624	$	44,705
	Work-in-process	118,993		95,937
	Finished goods	80,509		60,028
	Total inventories	$	247,126	$	200,670

Property_Equipment_and_Improve1

Property, Equipment and Improvements (Tables)	9 Months Ended
	Jan. 26, 2014
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment [Table Text Block]	'
	Property, equipment and improvements consist of the following as of January 26, 2014 and April 28, 2013:
	(in thousands)	January 26, 2014			April 28, 2013
	Land and buildings	$	46,134		$	29,834
	Computer equipment	51,328			54,868
	Office equipment, furniture and fixtures	4,420			5,373
	Machinery and equipment	399,873			352,032
	Leasehold property and improvements	35,088			32,665
	Total	536,843			474,772
	Accumulated depreciation and amortization	(289,449		)	(273,330		)
	Property, equipment and improvements (net)	$	247,394		$	201,442

Intangible_Assets_Tables

Intangible Assets (Tables)	9 Months Ended
	Jan. 26, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of Finite-Lived Intangible Assets by Major Class [Text Block]	'
	The following table reflects intangible assets subject to amortization as of January 26, 2014 and April 28, 2013:
		January 26, 2014
		Gross Carrying		Accumulated			Net Carrying
	(in thousands)	Amount		Amortization			Amount
	Purchased technology	$	101,044	$	(90,521	)	$	10,523
	Purchased trade name	1,172		(1,172		)	—
	Purchased customer relationships	26,944		(18,002		)	8,942
	Purchased internal use software, backlog and in-process research and development	3,396		(2,164		)	1,232
	Purchased patents	1,872		(593		)	1,279
	Total	$	134,428	$	(112,452	)	$	21,976
		April 28, 2013
		Gross Carrying		Accumulated			Net Carrying
	(in thousands)	Amount		Amortization			Amount
	Purchased technology	$	101,044	$	(86,786	)	$	14,258
	Purchased trade name	2,072		(2,072		)	—
	Purchased customer relationships	31,602		(21,120		)	10,482
	Purchased internal use software, backlog and in-process research and development	3,396		(1,920		)	1,476
	Purchased patents	1,872		(429		)	1,443
	Total	$	139,986	$	(112,327	)	$	27,659
Schedule of Expected Amortization Expense [Table Text Block]	'
	Estimated remaining amortization expense for the next five fiscal years and thereafter is as follows (in thousands):
	Year	Amount
	2014 (remainder of year)	$	1,610
	2015	6,356
	2016	6,092
	2017	4,065
	2018	2,149
	2019 and beyond	1,704
	Total	$	21,976

Debt_Tables

Debt (Tables)	9 Months Ended
	Jan. 26, 2014
Debt Disclosure [Abstract]	'
Convertible Debt [Table Text Block]	'
	The following table sets forth interest expense information related to the notes:
		Three and Nine Months Ended
	(in thousands, except percentages)	January 26, 2014
	Contractual interest expense	$	135
	Amortization of the debt discount	927
	Amortization of issuance costs	24
	Total interest cost	$	1,086
	Effective interest rate on the liability component	4.87		%
	The notes consisted of the following:
		As of
	(in thousands)	January 26, 2014
	Liability component:
	Principal	$	258,750
	Unamortized debt discount	(48,721		)
	Net carrying amount of the liability component	$	210,029
	Carrying amount of the equity component	$	49,648

Investments_Investments_Tables

Investments Investments (Tables)	9 Months Ended
	Jan. 26, 2014
Investments [Abstract]	'
Held-to-maturity Securities [Table Text Block]	'
	The Company's investments in fixed income securities as of January 26, 2014 and April 28, 2013 were as follows:
		January 26, 2014								April 28, 2013
				Gross Unrealized								Gross Unrealized
	(in thousands)	Amortized Cost		Gains		Losses		Fair Value		Amortized Cost		Gains		Losses		Fair Value
	Commercial paper	$	119,835	$	—	$	—	$	119,835	$	—	$	—	$	—	$	—
	Certificates of deposit	120,000		—		—		120,000		—		—		—		—
	Total	$	239,835	$	—	$	—	$	239,835	$	—	$	—	$	—	$	—
	Reported as:
	Cash equivalents	$	59,988	$	—	$	—	$	59,988	$	—	$	—	$	—	$	—
	Short-term investments	179,847		—		—		179,847		—		—		—		—
	Total	$	239,835	$	—	$	—	$	239,835	$	—	$	—	$	—	$	—

Warranty_Tables

Warranty (Tables)	9 Months Ended
	Jan. 26, 2014
Product Warranties Disclosures [Abstract]	'
Schedule of Product Warranty Liability [Table Text Block]	'
	Changes in the Company's warranty liability during the following period were as follows:
		Nine Months Ended
	(in thousands)	January 26, 2014
	Beginning balance at April 28, 2013	$	4,155
	Additions during the period based on product sold	4,618
	Change in estimate	(1,699		)
	Settlements and expirations	(1,875		)
	Ending balance at January 26, 2014	$	5,199

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Jan. 26, 2014
Fair Value Disclosures [Abstract]	'
Fair Value, Assets Measured on Recurring Basis [Table Text Block]	'
	The Company's financial instruments measured at fair value on a recurring basis as of January 26, 2014 and April 28, 2013 were as follows:
		January 26, 2014										April 28, 2013
		Carrying		Fair Value								Carrying		Fair Value
	(in thousands)	Amount		Level 1		Level 2		Level 3		Total		Amount		Level 1		Level 2		Level 3		Total
	Money market funds	$	15,324	$	15,324	$	—	$	—	$	15,324	$	—	$	—	$	—	$	—	$	—
	Commercial paper	119,835		—		119,835		—		119,835		—		—		—		—		—
	Certificates of deposit	120,000		—		120,000		—		120,000		—		—		—		—		—
	Total	$	255,159	$	15,324	$	239,835	$	—	$	255,159	$	—	$	—	$	—	$	—	$	—
Fair Value, Liabilities Measured on Recurring Basis [Table Text Block]	'
	The Company's financial instruments not measured at fair value on a recurring basis as of January 26, 2014 and April 28, 2013 were as follows:
		January 26, 2014										April 28, 2013
		Carrying		Fair Value								Carrying		Fair Value
	(in thousands)	Amount		Level 1		Level 2		Level 3		Total		Amount		Level 1		Level 2		Level 3		Total
	2029 Notes	$	40,015	$	86,720	$	—	$	—	$	86,720	$	40,015	$	59,931	$	—	$	—	$	59,931
	2033 Notes	258,750		268,923		—		—		268,923		—		—		—		—		—
	Short-term debt	4,230		—		4,230		—		4,230		—		—		—		—		—
	Total	$	302,995	$	355,643	$	4,230	$	—	$	359,873	$	40,015	$	59,931	$	—	$	—	$	59,931

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	9 Months Ended
	Jan. 26, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	'
	The Company's share-based compensation expense was recorded in the following cost and expense categories:
		Three Months Ended						Nine Months Ended
	(in thousands)	January 26, 2014			January 27, 2013			January 26, 2014		January 27, 2013
	Cost of revenues	$	2,140		$	1,992		$	6,163	$	5,058
	Research and development	3,760			2,401			10,866		8,323
	Sales and marketing	1,310			830			3,741		2,786
	General and administrative	2,558			2,167			7,509		7,814
	Total	$	9,768		$	7,390		$	28,279	$	23,981
Schedule of Common Stock Issued [Table Text Block]	'
	ommon stock issued or becoming vested under the Company's stock compensation plans was as follows:
		Three Months Ended					Nine Months Ended
		January 26, 2014		January 27, 2013			January 26, 2014		January 27, 2013
	Employee stock purchase plan	268,289		237,832			608,946		577,136
	Exercises of stock options	108,921		64,262			633,665		176,806
	Restricted stock units vesting	144,360		107,676			1,618,326		1,141,107

Basis_of_Presentation_Basis_of

Basis of Presentation Basis of Presentation (Details)	9 Months Ended
	Jan. 26, 2014
	Segments
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Number of reportable segments	1

Net_Income_Loss_per_Share_Comp

Net Income (Loss) per Share - Computation of Net Income (Loss) per Share (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jan. 26, 2014	Jan. 27, 2013	Jan. 26, 2014	Jan. 27, 2013
Numerator:	'	'	'	'
Net income (loss) attributable to Finisar Corporation (Numerator for basic net incomer per share)	$27,061	($3,407)	$83,037	($9,333)
Effect of dilutive securities: [Abstract]	'	'	'	'
Interest on Convertible Debt, Net of Tax	539	0	1,617	0
Numerator for basic and diluted net income (loss) per share	$27,600	($3,407)	$84,654	($9,333)
Denominator:	'	'	'	'
Denominator for basic net income (loss) per share - weighted average shares	96,394	93,097	95,649	92,624
Effect of dilutive securities:	'	'	'	'
Employee stock options and restricted stock units	4,219	0	4,094	0
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	3,748	0	3,748	0
Dilutive potential common shares	7,967	0	7,842	0
Denominator for diluted net income (loss) per share	104,361	93,097	103,491	92,624
Net income (loss) per share attributable to Finisar Corporation common stockholders:	'	'	'	'
Basic (in dollars per share)	$0.28	($0.04)	$0.87	($0.10)
Diluted (in dollars per share)	$0.26	($0.04)	$0.82	($0.10)

Net_Income_per_Share_AntiDilut

Net Income per Share - Anti-Dilutive (Details)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Jan. 26, 2014		Jan. 27, 2013		Jan. 26, 2014	Jan. 27, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'		'		'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	664		7,963		1,073	8,345
Employee Stock Options [Member]	'		'		'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'		'		'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	664		4,215		1,073	4,597
Convertible Senior Notes Due 2029 (Fiscal Year 2030) [Member] | Conversion of Convertible Subordinated Notes [Member]	'		'		'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'		'		'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0		3,748		0	3,748
0.5% Convertible Senior Notes Due 2033 [Member] | Conversion of Convertible Subordinated Notes [Member]	'		'		'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'		'		'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	[1]	0	[1]	0	0
[1]	0.50% Convertible Senior Notes due 2033 were excluded from the calculation of diluted earnings per share under the treasury stock method since the conversion price exceeded the average market price for the Company's common stock.

Inventories_Details

Inventories (Details) (USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, unless otherwise specified
Inventory, Net [Abstract]	'	'
Raw materials	$47,624	$44,705
Work-in-process	118,993	95,937
Finished goods	80,509	60,028
Total inventories	$247,126	$200,670

Property_Equipment_and_Improve2

Property, Equipment and Improvements (Details) (USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Total	$536,843	$474,772
Accumulated depreciation and amortization	-289,449	-273,330
Property, equipment and improvements (net)	247,394	201,442
Land and buildings [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total	46,134	29,834
Computer Equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total	51,328	54,868
Office Equipment, Furniture and Fixtures [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total	4,420	5,373
Machinery and Equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total	399,873	352,032
Leasehold property and Improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total	$35,088	$32,665

Intangible_Assets_Details

Intangible Assets (Details) (USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets, Net [Abstract]	'	'
Gross Carrying Amount	$134,428	$139,986
Accumulated Amortization	-112,452	-112,327
Purchased intangible assets, net	21,976	27,659
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'	'
2014 (remainder of year)	1,610	'
2015	6,356	'
2016	6,092	'
2017	4,065	'
2018	2,149	'
2019 and beyond	1,704	'
Purchased intangible assets, net	21,976	27,659
Purchased technology	'	'
Finite-Lived Intangible Assets, Net [Abstract]	'	'
Gross Carrying Amount	101,044	101,044
Accumulated Amortization	-90,521	-86,786
Purchased intangible assets, net	10,523	14,258
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'	'
Purchased intangible assets, net	10,523	14,258
Purchased trade name	'	'
Finite-Lived Intangible Assets, Net [Abstract]	'	'
Gross Carrying Amount	1,172	2,072
Accumulated Amortization	-1,172	-2,072
Purchased intangible assets, net	0	0
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'	'
Purchased intangible assets, net	0	0
Purchased customer relationships	'	'
Finite-Lived Intangible Assets, Net [Abstract]	'	'
Gross Carrying Amount	26,944	31,602
Accumulated Amortization	-18,002	-21,120
Purchased intangible assets, net	8,942	10,482
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'	'
Purchased intangible assets, net	8,942	10,482
Purchased internal use software, backlog and in-process research and development	'	'
Finite-Lived Intangible Assets, Net [Abstract]	'	'
Gross Carrying Amount	3,396	3,396
Accumulated Amortization	-2,164	-1,920
Purchased intangible assets, net	1,232	1,476
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'	'
Purchased intangible assets, net	1,232	1,476
Purchased patents	'	'
Finite-Lived Intangible Assets, Net [Abstract]	'	'
Gross Carrying Amount	1,872	1,872
Accumulated Amortization	-593	-429
Purchased intangible assets, net	1,279	1,443
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'	'
Purchased intangible assets, net	$1,279	$1,443

Debt_Details

Debt (Details) (USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, unless otherwise specified
Short-term Debt [Line Items]	'	'
Short-term Debt	$4,230	$0
Notes Payable to Banks [Member]	'	'
Short-term Debt [Line Items]	'	'
Short-term Debt	$4,200	'
Interest Rate	4.17%	'

Debt_Detail_2

Debt (Detail 2) (Convertible Debt [Member], 0.5% Convertible Senior Notes Due 2033 [Member], USD $)	1 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013
Debt Instrument [Line Items]	'
Principal	$258.80
Debt Instrument, Interest Rate, Stated Percentage	0.50%
Debt Instrument, Convertible, Conversion Price	$30.18
Debt Instrument, Convertible, Conversion Ratio	0.0331301
Debt Instrument, Redemption, Period One [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Instrument, Redemption, Period Two [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Instrument, Redemption, Period Three [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Instrument, Redemption, Period Four [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Instrument, Redemption, Period Five [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Instrument, Conversion, Option One [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Convertible, Threshold Trading Days	20
Debt Instrument, Convertible, Threshold Consecutive Trading Days	'30 days
Convertible Debt, Conversion Price, Threshold Percentage, Minimum	130.00%
Debt Instrument, Conversion, Option Two [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Convertible, Threshold Trading Days	5
Debt Instrument, Convertible, Threshold Consecutive Trading Days	'5 days
Convertible Debt, Conversion Price, Threshold Percentage, Minimum	98.00%

Debt_Carrying_Value_Details_3

Debt Carrying Value (Details 3) (USD $)	Jan. 26, 2014	Apr. 28, 2013	Jan. 26, 2014	Dec. 31, 2013	Jan. 26, 2014
			Convertible Debt [Member]	Convertible Debt [Member]	Convertible Debt [Member]
			0.5% Convertible Senior Notes Due 2033 [Member]	0.5% Convertible Senior Notes Due 2033 [Member]	Convertible Senior Notes Due 2029 (Fiscal Year 2030) [Member]
Carrying Amount [Line Items]	'	'	'	'	'
Debt Instrument, Interest Rate, Stated Percentage	'	'	'	0.50%	5.00%
Debt Instrument Convertible Carrying Amount Of Liability Component	'	'	$209,100,000	'	'
Debt Instrument, Convertible, Remaining Discount Amortization Period	'	'	'58 months	'	'
Principal	'	'	258,750,000	'	'
Unamortized debt discount	'	'	-48,721,000	'	'
Net Carrying amount of the liability component	'	'	210,029,000	'	'
Carrying Amount of Equity Component	'	'	49,648,000	'	'
Debt Instrument, Redemption Price, Percentage	'	'	'	'	100.00%
Convertible Debt, Current	$40,015,000	$0	'	'	$40,000,000

Debt_Convertible_Debt_Interest

Debt Convertible Debt Interest Expense (Details 4) (USD $)	9 Months Ended		1 Months Ended	3 Months Ended	9 Months Ended			3 Months Ended
	Jan. 26, 2014	Jan. 27, 2013	Dec. 31, 2013	Jan. 26, 2014	Jan. 26, 2014	Jan. 26, 2014	Jan. 26, 2014	Jan. 26, 2014
			Convertible Debt [Member]	Convertible Debt [Member]	Convertible Debt [Member]	Convertible Debt [Member]	Other Noncurrent Assets [Member]	Additional Paid-in Capital [Member]
			0.5% Convertible Senior Notes Due 2033 [Member]	0.5% Convertible Senior Notes Due 2033 [Member]	0.5% Convertible Senior Notes Due 2033 [Member]	Liability [Member]	Convertible Debt [Member]	Convertible Debt [Member]
						0.5% Convertible Senior Notes Due 2033 [Member]	0.5% Convertible Senior Notes Due 2033 [Member]	0.5% Convertible Senior Notes Due 2033 [Member]
Convertible Debt Interest Expense [Line Items]	'	'	'	'	'	'	'	'
Debt Instrument, Convertible, Conversion Ratio	'	'	0.0331301	'	'	'	'	'
Debt Issuance Cost	'	'	'	$3,800,000	'	'	'	'
Deferred Finance Costs, Noncurrent, Net	'	'	'	'	'	'	3,100,000	'
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	'	'	'	'	'	'	'	725,000
Contractual interest expense	'	'	'	'	135,000	'	'	'
Amortization of the debt discount	927,000	0	'	'	927,000	'	'	'
Amortization of Financing Costs	'	'	'	'	24,000	'	'	'
Total interest cost	'	'	'	'	$1,086,000	'	'	'
Effective interest rate on the liability component	'	'	'	'	'	4.87%	'	'

Investments_Investments_Detail

Investments Investments (Details) (USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, unless otherwise specified
Investment [Line Items]	'	'
Gross Unrealized Gains	$0	$0
Gross Unrealized Losses	0	0
Fair Value	239,835	0
Amortized Cost	239,835	0
Commercial Paper [Member]	'	'
Investment [Line Items]	'	'
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	119,835	0
Amortized Cost	119,835	0
Certificates of Deposit [Member]	'	'
Investment [Line Items]	'	'
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	120,000	0
Amortized Cost	120,000	0
Cash Equivalents [Member]	'	'
Investment [Line Items]	'	'
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	59,988	0
Amortized Cost	59,988	0
Short-term Investments [Member]	'	'
Investment [Line Items]	'	'
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	179,847	0
Amortized Cost	$179,847	$0

Investments_Minority_Investmen

Investments Minority Investments (Details) (USD $)	Jan. 26, 2014	Apr. 28, 2013	Jan. 26, 2014	Jan. 26, 2014
	companies	companies	Other Nonoperating Income (Expense) [Member]	Other Nonoperating Income (Expense) [Member]
Investment [Line Items]	'	'	'	'
Cost Method Investments	$884,000	$884,000	'	'
Cost Method Investment, Number of Companies	1	1	'	'
Equity Method Investments	1,157,000	0	'	'
Equity Method Investment, Number of Companies	1	0	'	'
Equity Method Investment, Ownership Percentage	19.90%	'	'	'
Income (Loss) from Equity Method Investments	'	'	$200,000	$509,000

Warranty_Details

Warranty (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Jan. 26, 2014
Movement in Standard Product Warranty Accrual [Roll Forward]	'
Beginning balance at April 28, 2013	$4,155
Additions during the period based on product sold	4,618
Change in estimate	-1,699
Settlements and expirations	-1,875
Ending balance at January 26, 2014	$5,199

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments (Details) (USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, unless otherwise specified	companies
Financial assets [Abstract]	'	'
Minority Investments, Number of Companies	2	'
Minority investments	$2,041	$884
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member]	'	'
Financial assets [Abstract]	'	'
Total	255,159	0
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member] | Money Market Funds [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	15,324	0
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member] | Commercial Paper [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	119,835	0
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member] | Certificates of Deposit [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	120,000	0
Fair Value, Measurements, Recurring [Member] | Fair Value [Member]	'	'
Financial assets [Abstract]	'	'
Total	255,159	0
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Money Market Funds [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	15,324	0
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Commercial Paper [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	119,835	0
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Certificates of Deposit [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	120,000	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Fair Value [Member]	'	'
Financial assets [Abstract]	'	'
Total	15,324	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Fair Value [Member] | Money Market Funds [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	15,324	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Fair Value [Member] | Commercial Paper [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Fair Value [Member] | Certificates of Deposit [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Fair Value [Member]	'	'
Financial assets [Abstract]	'	'
Total	239,835	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Fair Value [Member] | Money Market Funds [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Fair Value [Member] | Commercial Paper [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	119,835	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Fair Value [Member] | Certificates of Deposit [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	120,000	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Fair Value [Member]	'	'
Financial assets [Abstract]	'	'
Total	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Fair Value [Member] | Money Market Funds [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Fair Value [Member] | Commercial Paper [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Fair Value [Member] | Certificates of Deposit [Member]	'	'
Financial assets [Abstract]	'	'
Cash and Cash Equivalents, Fair Value Disclosure	$0	$0

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments (Details 2) (Fair Value, Measurements, Recurring [Member], USD $)	Jan. 26, 2014	Apr. 28, 2013
In Thousands, unless otherwise specified
Carrying Amount [Member]	'	'
Debt Instrument [Line Items]	'	'
Total	$302,995	$40,015
Fair Value [Member]	'	'
Debt Instrument [Line Items]	'	'
Total	359,873	59,931
Fair Value [Member] | Level 1 [Member]	'	'
Debt Instrument [Line Items]	'	'
Total	355,643	59,931
Fair Value [Member] | Level 2 [Member]	'	'
Debt Instrument [Line Items]	'	'
Total	4,230	0
Fair Value [Member] | Level 3 [Member]	'	'
Debt Instrument [Line Items]	'	'
Total	0	0
Convertible Senior Notes Due 2029 (Fiscal Year 2030) [Member] | Carrying Amount [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	40,015	40,015
Convertible Senior Notes Due 2029 (Fiscal Year 2030) [Member] | Fair Value [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	86,720	59,931
Convertible Senior Notes Due 2029 (Fiscal Year 2030) [Member] | Fair Value [Member] | Level 1 [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	86,720	59,931
Convertible Senior Notes Due 2029 (Fiscal Year 2030) [Member] | Fair Value [Member] | Level 2 [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	0	0
Convertible Senior Notes Due 2029 (Fiscal Year 2030) [Member] | Fair Value [Member] | Level 3 [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	0	0
0.5% Convertible Senior Notes Due 2033 [Member] | Carrying Amount [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	258,750	0
0.5% Convertible Senior Notes Due 2033 [Member] | Fair Value [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	268,923	0
0.5% Convertible Senior Notes Due 2033 [Member] | Fair Value [Member] | Level 1 [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	268,923	0
0.5% Convertible Senior Notes Due 2033 [Member] | Fair Value [Member] | Level 2 [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	0	0
0.5% Convertible Senior Notes Due 2033 [Member] | Fair Value [Member] | Level 3 [Member]	'	'
Debt Instrument [Line Items]	'	'
Convertible notes	0	0
Notes Payable to Banks [Member] | Carrying Amount [Member]	'	'
Debt Instrument [Line Items]	'	'
Short-term debt	4,230	0
Notes Payable to Banks [Member] | Fair Value [Member]	'	'
Debt Instrument [Line Items]	'	'
Short-term debt	4,230	0
Notes Payable to Banks [Member] | Fair Value [Member] | Level 1 [Member]	'	'
Debt Instrument [Line Items]	'	'
Short-term debt	0	0
Notes Payable to Banks [Member] | Fair Value [Member] | Level 2 [Member]	'	'
Debt Instrument [Line Items]	'	'
Short-term debt	4,230	0
Notes Payable to Banks [Member] | Fair Value [Member] | Level 3 [Member]	'	'
Debt Instrument [Line Items]	'	'
Short-term debt	$0	$0

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	3 Months Ended		9 Months Ended
	Jan. 26, 2014	Jan. 27, 2013	Jan. 26, 2014	Jan. 27, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock based compensation expense	$9,768,000	$7,390,000	$28,279,000	$23,981,000
Stock issued under Employee Stock Purchase Plan	268,289	237,832	608,946	577,136
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	108,921	64,262	633,665	176,806
Restricted stock units vested	144,360	107,676	1,618,326	1,141,107
Net compensation expense related to unvested shares not yet recognized	71,600,000	'	71,600,000	'
Period to recognize net compensation expense related to unvested shares not yet recognized	'	'	'31 months	'
Stock-based compensation capitalized	'	'	2,000,000	'
Cost of Revenues [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock based compensation expense	2,140,000	1,992,000	6,163,000	5,058,000
Research and Development [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock based compensation expense	3,760,000	2,401,000	10,866,000	8,323,000
Selling and Marketing Expense [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock based compensation expense	1,310,000	830,000	3,741,000	2,786,000
General and Administrative [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock based compensation expense	$2,558,000	$2,167,000	$7,509,000	$7,814,000

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Jan. 26, 2014	Jan. 27, 2013	Jan. 26, 2014	Jan. 27, 2013
Provision for income taxes	$2,827	$2,153	$4,816	$1,733
United States [Member]	'	'	'	'
Valuation allowance as a percent of deferred tax assets	94.00%	'	94.00%	'

Pending_Litigation_Details

Pending Litigation (Details) (Pending Litigation [Member], Stock Options Cases [Member], USD $)	Jan. 26, 2014
Gain Contingencies [Line Items]	'
Former Gain Contingency, Recognized in Current Period	$12,750,000
Contingent Legal Fees, Plaintiff	6,300,000
Gain Contingency, Legal Fees, Defense	3,000,000
Insurance Settlement [Member]	'
Gain Contingencies [Line Items]	'
Former Gain Contingency, Recognized in Current Period	12,500,000
Positive Outcome of Litigation [Member]	'
Gain Contingencies [Line Items]	'
Former Gain Contingency, Recognized in Current Period	$250,000

Pending_Litigation_Pending_Lit

Pending Litigation Pending Litigation (Details 2) (Details) (Pending Litigation [Member], USD $)	9 Months Ended			9 Months Ended		9 Months Ended	0 Months Ended
	Jan. 26, 2014	Jan. 26, 2014	Mar. 08, 2011	Jan. 26, 2014	Nov. 30, 2006	Jan. 26, 2014	Dec. 23, 2011
	Cheetah Omni [Member]	Earnings Announcements Cases [Member]	Earnings Announcements Cases [Member]	Stock Options Cases [Member]	Stock Options Cases [Member]	Cheetah Omni Asserting Infringement, ROADM products [Member]	Finisar Michigan Litigation [Member]
	patent		lawsuit		lawsuit	patent	patent
						defendant
Loss Contingencies [Line Items]	'	'	'	'	'	'	'
Loss Contingency, Patents Allegedly Infringed, Number	7	'	'	'	'	2	4
Loss Contingency, Number of Defendants	'	'	'	'	'	6	'
Loss Contingency, Pending Claims, Number	'	'	2	'	2	'	'
Loss Contingency, Damages Sought, Value	'	$0	'	$0	'	'	'

Guarantees_and_Indemnification1

Guarantees and Indemnifications Guarantees and Indemnifications (Details)	3 Months Ended
	Jan. 26, 2014
Guarantees [Abstract]	'
Indemnification, Period for Written Notice	'90 days

Related_Party_Transaction_Deta

Related Party Transaction (Details) (Immediate Family Member of Management or Principle Owner [Member], USD $)	3 Months Ended				9 Months Ended
	Jan. 26, 2014	Jul. 28, 2013	Jan. 27, 2013	Jul. 29, 2012	Jan. 26, 2014	Jan. 27, 2013	Jun. 14, 2013
Related Party Transaction [Line Items]	'	'	'	'	'	'	'
Related party transaction expense	$46,004	'	$50,466	'	$152,082	$152,690	'
Proceeds from Issuance of Restrcited Stock to Related Party	'	0	'	'	'	'	'
Related Party Transaction Restricted Stock Units Granted to Related Party	'	4,164	'	3,814	'	'	'
Fair value of Restricted Stock Units granted to related party	'	$66,957	'	$49,086	'	'	'
Related party transaction, vesting rate of Restricted Stock Units	'	'	'	'	'	'	25.00%
Vesting on June 24, 2014 [Member]	'	'	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'	'	'
Related party transaction, vesting rate of Restricted Stock Units	25.00%	'	'	'	25.00%	'	'
Vested on Each of Next Three Anniversaries Thereafter, Fully Vested on June 24, 2017 [Member]	'	'	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'	'	'
Related party transaction, vesting rate of Restricted Stock Units	25.00%	'	'	'	25.00%	'	'
Vested on Each of Next Three Anniversaries Thereafter, Fully Vested on June 14, 2016 [Member]	'	'	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'	'	'
Related party transaction, vesting rate of Restricted Stock Units	25.00%	'	'	'	25.00%	'	'

Subsequent_Event_Details

Subsequent Event (Details) (u2t [Member], Subsequent Event [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Jan. 26, 2014
u2t [Member] | Subsequent Event [Member]	'
Subsequent Event [Line Items]	'
Cash	$20