Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Net income	$ 17,294	$ 11,138	$ 32,430	$ 26,056
Other comprehensive income:
Cumulative translation adjustments	405	719	1,624	1,003
Changes in market value of investments:
Changes in unrealized gains (losses)	3	(24)	7	97
Total net change in market value of investments	3	(24)	7	97
Changes in market value of derivatives:
Changes in market value of derivatives, net of taxes (benefit) of $31, ($17), $35 and ($6)	56	(29)	55	(16)
Reclassification adjustment for net (losses) gains included in net income, net of (benefits) taxes of ($15), ($6), $85 and $94	(25)	(9)	164	154
Total net change in market value of derivatives	31	(38)	219	138
Other comprehensive income	439	657	1,850	1,238
Comprehensive income	$ 17,733	$ 11,795	$ 34,280	$ 27,294