Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 33,291	$ (28,369)	$ 61,192
Other comprehensive income (loss):
Cumulative translation adjustments	(1,000)	1,446	(6,311)
Recognition of actuarial net (loss) gain from pension and other post-retirement plans, net of (benefit) taxes of ($368), $215 and $0	(858)	632	0
Changes in market value of investments:
Changes in unrealized (losses) gains, net of taxes of $0, $0 and $0	(59)	3	(12)
Total net change in market value of investments	(59)	3	(12)
Changes in market value of derivatives:
Changes in market value of derivatives, net of tax (benefits) of ($167), ($329) and ($1,113)	(277)	(523)	(1,937)
Reclassification adjustment for net gains included in net income (loss), net of taxes of $135, $915 and $497	223	1,586	843
Total net change in market value of derivatives	(54)	1,063	(1,094)
Other comprehensive income (loss)	(1,971)	3,144	(7,417)
Total comprehensive income (loss)	$ 31,320	$ (25,225)	$ 53,775