CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (650,011)	$ (160,376)	$ (65,349)
Other comprehensive income (loss):
Unrealized gains (losses) on available for sale securities, net of tax of $61, ($239) and $0, respectively	113	(443)	143
Change in loss on derivative contract, net of tax of $823, $77 and $0, respectively	1,530	143	717
Change in supplemental executive retirement plan pension liability, net of tax of ($927), $1,264 and $0, respectively	(1,721)	2,347	(1,845)
Change in pension plan minimum liability, net of tax of $215, $1,093 and $0, respectively	399	2,029	(5,739)
Change in other benefit plan minimum liability, net of tax of ($2,046), $5,081 and ($769), respectively	(3,799)	9,436	(1,429)
Total comprehensive loss	$ (653,489)	$ (146,864)	$ (73,502)