v3.8.0.1
Debt and Credit Facility Amortization and Interest Expense (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Debt Instrument [Line Items]        
Amortization of debt issuance costs     $ 3,339 $ 2,118
Amortization of debt discount on convertible debt     $ 52,306 24,413
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 4 months 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 4 months 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 4 months 16 days  
2007 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)     20 years 2 months 16 days  
Convertible Debt        
Debt Instrument [Line Items]        
Amortization of debt issuance costs $ 900 $ 400 $ 1,800 800
Amortization of debt discount on convertible debt 26,300 12,300 52,300 24,400
Coupon interest expense 19,400 10,100 38,800 20,200
Total $ 46,600 $ 22,800 $ 92,900 $ 45,400