Net Income per Share - Computation of Net Income per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 30, 2011	Oct. 31, 2010	Oct. 30, 2011	Oct. 31, 2010
Numerator:
Net income attributable to Finisar Corporation (Numerator for basic net incomer per share)	$ 5,927	$ 33,796	$ 16,069	$ 52,922
Effect of dilutive securities:
Convertible debt interest expense	0	1,373	0	2,743
Numerator for diluted net income per share	$ 5,927	$ 35,169	$ 16,069	$ 55,665
Denominator:
Denominator for basic net income per share - weighted average shares	90,715	76,766	90,470	76,433
Effect of dilutive securities:
Employee stock options and restricted stock units	2,848	3,248	3,206	3,061
Warrants	36	36	36	36
Convertible debt	0	9,471	0	9,483
Dilutive potential common shares	2,884	12,755	3,242	12,580
Denominator for diluted net income per share	93,599	89,521	93,712	89,013
Net income per share attributable to Finisar Corporation common stockholders:
Basic (in dollars per share)	$ 0.07	$ 0.44	$ 0.18	$ 0.69
Diluted (in dollars per share)	$ 0.06	$ 0.39	$ 0.17	$ 0.63