Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	$ 453,426	$ 292,723
Less allowance for doubtful accounts	2,384	2,540
Accounts receivable, net	451,042	290,183
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	449,495	289,013
Other Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	$ 3,931	$ 3,710