Supplemental Cash Flow Information (Details 4) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Business Acquisition [Line Items]
Income taxes paid, net of refunds received	$ (24,246)	$ 1,370
Cash paid for interest	52,250	30,110
Additional capital lease obligation to finance property and equipment	20,160	15,688
Convertible senior subordinated notes
Business Acquisition [Line Items]
Shares issued in connection with certain redemptions (in shares)		1,849,596
Capital Lease Obligations [Member]
Business Acquisition [Line Items]
Additional capital lease obligation to finance property and equipment	$ 0	$ 36