Debt - Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Debt Instrument [Line Items]
Debt issuance amortization	$ 4.8	$ 4.2
Debt discount amortization	25.3	29.9
Other interest expense	1.0	0.5
Total interest expense	99.1	132.6
Senior Secured Indebtedness
Debt Instrument [Line Items]
Debt issuance amortization	4.1	3.3
Debt discount amortization	1.5	0.7
Interest expense	52.7	78.7
Total interest expense	58.3	82.7
Convertible Debt
Debt Instrument [Line Items]
Debt issuance amortization	0.7	0.9
Debt discount amortization	23.8	29.2
Interest expense	15.3	19.3
Total interest expense	$ 39.8	$ 49.4