Financial Instruments, Hedging Activities and Fair Value Measurements - Instruments Designated as Cash Flow Hedges in AOCI (Details) - Level 2 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives used in hedging	$ 98.1	$ 10.5
Interest rate caps | Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives used in hedging	2.6	3.5
Interest rate swaps | Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives used in hedging	60.0	29.4
Foreign currency forward contracts | Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives used in hedging	0.3	0.0
Cross-currency swaps | Net Investment Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives used in hedging	$ 35.2	$ (22.4)