Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Mar. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	$ 226,934	$ 232,719
Less allowance for doubtful accounts	2,661	2,764
Accounts receivable, net	224,273	229,955
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	224,832	230,469
Other Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	$ 2,102	$ 2,250