Financial Instruments - Fair Values of Derivative Instruments in Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 2.5	$ 1.6
Liability Derivatives	3.6	176.9
Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	0.0	0.0
Liability Derivatives	1.8	1.9
Derivatives designated as hedging instruments | Other Current Assets | Interest rate contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives	0.0	0.0
Derivatives designated as hedging instruments | Other Accrued & Current Liabilities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Liability Derivatives	1.8	1.9
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Asset Derivatives	2.5	1.6
Liability Derivatives	1.8	175.0
Derivatives not designated as hedging instruments | Other Current Assets | Make-whole derivative liability
Derivatives, Fair Value [Line Items]
Asset Derivatives	0.0	0.0
Derivatives not designated as hedging instruments | Other Current Assets | Foreign exchange forward contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives	2.5	1.6
Derivatives not designated as hedging instruments | Other Accrued & Current Liabilities | Foreign exchange forward contracts
Derivatives, Fair Value [Line Items]
Liability Derivatives	1.8	2.6
Derivatives not designated as hedging instruments | Make-whole derivative liability | Make-whole derivative liability
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 0.0	$ 172.4