Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 79,812	$ 33,291	$ (28,369)
Other comprehensive income (loss):
Cumulative translation adjustments	4,889	(1,000)	1,446
Recognition of actuarial net gain (loss) from pension and other post-retirement plans, net of taxes (benefit) of $435, ($368) and $215	1,353	(858)	632
Changes in market value of investments:
Changes in unrealized (losses) gains, net of (benefit) taxes of $15, $0 and $0	(6)	(59)	3
Total net change in market value of investments	(6)	(59)	3
Changes in market value of derivatives:
Changes in market value of derivatives, net of tax (benefits) of $267, ($167), and ($329)	812	(277)	(523)
Reclassification adjustment for net (losses) gains included in net income (loss), net of (benefit) taxes of ($219), $135, and $915	(681)	223	1,586
Total net change in market value of derivatives	131	(54)	1,063
Other comprehensive income (loss)	6,367	(1,971)	3,144
Total comprehensive income (loss)	$ 86,179	$ 31,320	$ (25,225)