Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	$ 234,992	$ 232,719
Less allowance for doubtful accounts	2,730	2,764
Accounts receivable, net	232,262	229,955
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	232,494	230,469
Other Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	$ 2,498	$ 2,250