Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 17,629us-gaap_NetIncomeLoss	$ 17,294us-gaap_NetIncomeLoss	$ 40,338us-gaap_NetIncomeLoss	$ 32,430us-gaap_NetIncomeLoss
Other comprehensive income:
Cumulative translation adjustments	(1,290)	405	(3,397)	1,624
Changes in market value of investments:
Changes in unrealized (losses) gains	(75)	3	(54)	7
Total net change in market value of investments	(75)	3	(54)	7
Changes in market value of derivatives:
Changes in market value of derivatives, net of (benefits) taxes of ($327), $31, ($595) and $35	(597)	56	(1,068)	55
Reclassification adjustment for net gains (losses) included in net income, net of taxes (benefits) of $133, ($15), $115 and $85	214	(25)	195	164
Total net change in market value of derivatives	(383)	31	(873)	219
Other comprehensive (loss) income	(1,748)	439	(4,324)	1,850
Total comprehensive income	$ 15,881us-gaap_ComprehensiveIncomeNetOfTax	$ 17,733us-gaap_ComprehensiveIncomeNetOfTax	$ 36,014us-gaap_ComprehensiveIncomeNetOfTax	$ 34,280us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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