Financial Information by Quarter (Unaudited) (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	May 03, 2015	Jan. 25, 2015	Oct. 26, 2014	Jul. 27, 2014	Apr. 27, 2014	Jan. 26, 2014	Oct. 27, 2013	Jul. 28, 2013	May 03, 2015	Apr. 27, 2014	Apr. 28, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 320,042,000	$ 306,283,000	$ 296,981,000	$ 327,638,000	$ 306,025,000	$ 294,018,000	$ 290,722,000	$ 266,068,000
Gross profit	89,217,000	77,953,000	84,921,000	98,819,000	96,564,000	105,689,000	103,373,000	91,373,000	350,910,000	396,999,000	257,041,000
Income (loss) from operations	10,284,000	3,401,000	(7,259,000)	20,368,000	21,107,000	33,096,000	30,109,000	27,103,000	26,794,000	111,415,000	(5,555,000)
Income (loss) before non-controlling interest	7,327,000	1,678,000	(11,361,000)	14,243,000	28,683,000	27,068,000	29,951,000	25,835,000
Net income (loss) attributable to Finisar Corporation	7,327,000	1,678,000	(11,361,000)	14,243,000	28,750,000	27,061,000	29,965,000	26,011,000	11,887,000	111,787,000	(5,454,000)
Net income (loss) per share attributable to Finisar Corporation common stockholders:
Basic (in usd)	$ 0.07	$ 0.02	$ (0.11)	$ 0.14	$ 0.30	$ 0.28	$ 0.31	$ 0.27	$ 0.12	$ 1.16	$ (0.06)
Diluted (in usd)	$ 0.07	$ 0.02	$ (0.11)	$ 0.14	$ 0.28	$ 0.26	$ 0.29	$ 0.26	$ 0.11	$ 1.09	$ (0.06)
Shares used in computing net income (loss) per share:
Basic (in shares)	104,005	103,563	99,621	98,241	96,965	96,394	95,941	94,609	101,408	95,979	92,860
Diluted (in shares)	107,535	105,990	99,621	106,036	105,418	104,361	103,696	101,125	104,970	104,112	92,860
Impairment of long-lived assets		5,800,000
Litigation settlement			(11,000,000)
Gain on divestiture of majority-owned subsidiary					8,200,000
Gain (loss) related to litigation settlement								$ 6,500,000