Derivative Instruments and Fair Value Accounting - Assets and liabilities Measured at fair value on recurring basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Level 1
Assets:
Cash equivalents		$ 12.3	$ 24.2
Restricted cash		164.7	96.4
Total assets		177.0	120.6
Level 2
Assets:
Total assets	[1]	1.1	4.8
Level 2 | Other Assets [Member]
Assets:
Foreign currency hedge (1)	[1]	1.1	4.8
Level 2 | Accrued Liabilities [Member]
Liabilities [Abstract]
Total liabilities	[2]	32.4	45.2
Level 3
Assets:
Total assets		0.0	0.0
Interest Rate Swap [Member] | Level 2 | Accrued Liabilities [Member]
Liabilities [Abstract]
Interest rate hedge (2)	[2]	$ 32.4	$ 45.2

[1] (Mark One)

[2] (Mark One)