CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 19,953	$ 20,474	$ 38,781	$ 40,861
Other comprehensive income (loss):
Foreign currency translation adjustments	57	4	257	(250)
Unrealized gains (losses) on cash flow hedges:
Unrealized cash flow hedge gains (losses) arising during the period	(2,302)	(650)	(4,647)	304
Net (gains) losses reclassified into income for revenue hedges	1,131	(825)	1,149	(985)
Net (gains) losses reclassified into income for cost of revenue hedges	(174)	589	(132)	1,316
Net unrealized gains (losses) on cash flow hedges	(1,345)	(886)	(3,630)	635
Unrealized holding gains (losses) during the period	133	(272)	209	42
Aggregate income tax benefit (expense) of the above items	(19)	98	1	(26)
Other comprehensive income (loss)	(1,174)	(1,056)	(3,163)	401
Comprehensive income	$ 18,779	$ 19,418	$ 35,618	$ 41,262