Hedging Activities, Derivative Instruments and Fair Value Measurements - Comprehensive Income (Loss) (Details) - Interest Rate Swaps - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Gains and Losses on Derivatives Designated as Cash Flow Hedges [Abstract]
Loss recognized in AOCI on derivatives	$ 0.0	$ (0.1)	$ 0.0	$ (4.4)
Loss reclassified from AOCI into income (effective portion)	$ 0.0	$ (5.3)	$ 0.0	$ (18.5)