Consolidated Statements of Comprehensive Income (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	$ 11,233	$ 9,883	$ 22,709	$ 15,136
Other comprehensive income:
Cumulative translation adjustments	(1,675)	928	(2,107)	1,219
Changes in market value of investments:
Changes in unrealized (losses) gains	(23)	39	21	4
Total net change in market value of investments	(23)	39	21	4
Changes in market value of derivatives:
Changes in market value of derivatives, net of (benefits) taxes of ($360), $76, ($272) and $1	(603)	124	(467)	2
Reclassification adjustment for net gains (losses) included in net income, net of taxes (benefits) of $51, $71, ($14) and $103	81	113	(23)	186
Total net change in market value of derivatives	(522)	237	(490)	188
Other comprehensive (loss) income	(2,220)	1,204	(2,576)	1,411
Comprehensive income	$ 9,013	$ 11,087	$ 20,133	$ 16,547