Basis of Presentation and Significant Accounting Policies Restatement of Previously Reported Financial Information (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Mar. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories	$ 938,808	$ 791,340	$ 884,515
Retained deficit	(177,361)	(145,856)	(237,338)	$ (211,388)
Pension, postretirement and other long-term liabilities	$ 81,008	$ 81,753	101,109
Restatement Adjustment | Adjustment For Accounting Errors
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories			1,380
Recoverable income tax			1,824
Retained deficit			3,204
Accounts receivable, related parties			(11,808)
Pension, postretirement and other long-term liabilities			$ 11,808