Derivative Instruments and Fair Value Accounting - Assets and liabilities Measured at fair value on recurring basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019
Level 1
Assets:
Cash equivalents		$ 24.2	$ 57.9
Restricted cash		101.1	111.4
Total assets		125.3	169.3
Level 2
Assets:
Total assets	[1]	2.1	1.2
Level 2 | Other Assets [Member]
Assets:
Foreign currency hedge (1)	[1]	2.1	1.2
Level 2 | Accrued Liabilities [Member]
Liabilities [Abstract]
Total liabilities	[2]	50.0	28.0
Level 3
Assets:
Total assets		0.0
Interest Rate Swap [Member] | Level 2 | Accrued Liabilities [Member]
Liabilities [Abstract]
Interest rate hedge (2)	[2]	$ 50.0	$ 28.0

[1] (Mark One)

[2] (Mark One)