Significant Accounting Policies, Leases (Details) $ in Millions	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($) Lease
Leases [Abstract]
Right-of-use assets	$ 61.4	$ 61.3
Operating lease liabilities, current	10.9	12.4
Operating lease liabilities, noncurrent	50.3	48.9
Operating lease liabilities	$ 61.2
Build-to-Suit Arrangements [Member]
Leases [Abstract]
Right-of-use assets		5.2
Operating lease liabilities		$ 5.2
Number of operating leases | Lease		2