Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets:
Cash equivalents	$ 210.7	$ 4.1
Foreign exchange forwards
Assets:
Derivative asset	2.5	1.6
Liabilities:
Derivative Liability	1.8	2.6
Swap arrangements
Liabilities:
Derivative Liability	1.8	1.9
Make-whole derivative liability
Liabilities:
Derivative Liability		172.4
Quoted Prices in Active Markets for Identical Assets (Level I)
Assets:
Cash equivalents	210.7	4.1
Quoted Prices in Active Markets for Identical Assets (Level I) | Foreign exchange forwards
Assets:
Derivative asset	0.0	0.0
Liabilities:
Derivative Liability	0.0	0.0
Quoted Prices in Active Markets for Identical Assets (Level I) | Swap arrangements
Liabilities:
Derivative Liability	0.0	0.0
Quoted Prices in Active Markets for Identical Assets (Level I) | Make-whole derivative liability
Liabilities:
Derivative Liability		0.0
Significant Other Observable Inputs (Level II)
Assets:
Cash equivalents	0.0	0.0
Significant Other Observable Inputs (Level II) | Foreign exchange forwards
Assets:
Derivative asset	2.5	1.6
Liabilities:
Derivative Liability	1.8	2.6
Significant Other Observable Inputs (Level II) | Swap arrangements
Liabilities:
Derivative Liability	1.8	1.9
Significant Other Observable Inputs (Level II) | Make-whole derivative liability
Liabilities:
Derivative Liability		0.0
Significant Unobservable Inputs (Level III)
Assets:
Cash equivalents	0.0	0.0
Significant Unobservable Inputs (Level III) | Foreign exchange forwards
Assets:
Derivative asset	0.0	0.0
Liabilities:
Derivative Liability	0.0	0.0
Significant Unobservable Inputs (Level III) | Swap arrangements
Liabilities:
Derivative Liability	$ 0.0	0.0
Significant Unobservable Inputs (Level III) | Make-whole derivative liability
Liabilities:
Derivative Liability		$ 172.4