Debt and Credit Facility Amortization and Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Amortization of debt issuance costs			$ 4,952	$ 3,182
Amortization of debt discount on convertible debt			$ 79,017	36,907
2017 Senior Subordinated Convertible Debt
Debt Instrument [Line Items]
Remaining period, in years, over which unamortized debt discount will be recognized as non-cash interest expense (in years)			9 years 1 month 16 days
2015 Senior Subordinated Convertible Debt
Debt Instrument [Line Items]
Remaining period, in years, over which unamortized debt discount will be recognized as non-cash interest expense (in years)			7 years 1 month 16 days
2017 Junior Subordinated Convertible Debt
Debt Instrument [Line Items]
Remaining period, in years, over which unamortized debt discount will be recognized as non-cash interest expense (in years)			19 years 1 month 16 days
Convertible Debt
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 900	$ 500	$ 2,700	1,300
Amortization of debt discount on convertible debt	26,700	12,500	79,000	36,900
Coupon interest expense	19,300	10,100	58,100	30,300
Total	$ 46,900	$ 23,100	$ 139,800	$ 68,500