Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 89,685	$ 21,245	$ 62,995	$ 10,981
Other comprehensive income (loss):
Cumulative translation adjustments	(195)	(2,022)	3,435	(2,109)
Changes in market value of investments:
Changes in unrealized losses, net of taxes of ($22), $0, ($16) and $0, respectively	(41)	(49)	(32)	(88)
Total net change in market value of investments	(41)	(49)	(32)	(88)
Changes in market value of derivatives:
Changes in market value of derivatives, net of taxes (benefits) of ($47), ($189), $299 and ($242), respectively	(66)	(299)	497	(384)
Reclassification adjustment for net gains (losses) included in net income, net of taxes (benefits) of ($96), $73, ($238), and $77, respectively	(157)	120	(382)	127
Total net change in market value of derivatives	(223)	(179)	115	(257)
Other comprehensive income (loss)	(459)	(2,250)	3,518	(2,454)
Total comprehensive income	$ 89,226	$ 18,995	$ 66,513	$ 8,527