Debt - Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Debt issuance cost amortization			$ 5.7	$ 7.1
Debt discount amortization			18.8	5.4
Other interest expense	$ 1.2	$ 1.2	3.6	3.8
Total interest expense	49.2	52.8	143.2	156.4
Senior Indebtedness
Debt Instrument [Line Items]
Debt issuance cost amortization	1.0	1.7	3.6	5.1
Debt discount amortization	14.0	1.8	18.8	5.4
Interest expense	31.9	46.8	113.8	137.8
Total interest expense	46.9	50.3	136.2	148.3
Convertible Debt
Debt Instrument [Line Items]
Debt issuance cost amortization	0.7	0.7	2.1	2.0
Interest expense	0.4	0.6	1.3	2.3
Total interest expense	$ 1.1	$ 1.3	$ 3.4	$ 4.3