Long-Term Debt (Schedule of Long-term Debt) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,698,600	$ 937,500
Current portion of long-term debt	7,200	0
Principal amount	1,691,400	937,500
Less: unamortized discount	(6,289)	(3,086)
Long-term debt, net of unamortized discount	1,685,111	934,414
2012 ABL Revolver | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt, gross	66,100	0
Senior Notes | 2013 Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	400,000	400,000
Senior Notes | 2012 Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	250,000	250,000
Term Loans | 2012 Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	262,500	287,500
Term Loans | Amendment 2 2012 Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	$ 720,000	$ 0