Basis of Presentation and Significant Accounting Policies Restatement of Previously Reported Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Mar. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories	$ 963,390	$ 963,390	$ 944,012	$ 791,340
Retained deficit	(258,403)	(258,403)	(193,019)	(145,856)		$ (211,388)
Pension, postretirement and other long-term liabilities	95,367	95,367	$ 79,630	$ 81,753
Restatement Adjustment | Adjustment For Accounting Errors
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of goods sold	636	636
Inventories	744	744
Recoverable income tax	1,824	1,824
Retained deficit	2,568	2,568
Accounts receivable, related parties	$ (11,808)	$ (11,808)
Pension, postretirement and other long-term liabilities					$ 11,808