CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 27,421	$ 23,138	$ 56,093	$ 50,091
Other comprehensive income (loss):
Foreign currency translation adjustments	11	311	74	(41)
Unrealized gains (losses) on cash flow hedges:
Unrealized cash flow hedge gains (losses) arising during the period	3,023	(1,983)	3,096	(3,646)
Net (gains) losses reclassified into income for revenue hedges	289	130	1,159	146
Net (gains) losses reclassified into income for cost of revenue hedges	(104)	26	(212)	(244)
Net unrealized gains (losses) on cash flow hedges	3,208	(1,827)	4,043	(3,744)
Unrealized holding gains (losses) during the period	(42)	221	35	7
Aggregate income tax benefit (expense) of the above items	(43)	(25)	(79)	72
Other comprehensive income (loss)	3,134	(1,320)	4,073	(3,706)
Comprehensive income	$ 30,555	$ 21,818	$ 60,166	$ 46,385