Accumulated Other Comprehensive Income (Loss) - Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Interest expense	$ 111.1	$ 88.9	$ 99.6
Benefit for income taxes	(13.0)	(31.8)	(80.1)
Net income (loss) attributable to parent	(33.3)	159.1	269.4
Reclassification out of Accumulated Other Comprehensive (Loss) Income
Income Statement [Abstract]
Net income (loss) attributable to parent	16.1	13.6	12.9
Unrealized Gains (Losses) on Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive (Loss) Income
Income Statement [Abstract]
Interest expense	18.5	15.6	15.1
Benefit for income taxes	(4.6)	(3.7)	(3.6)
Net income (loss) attributable to parent	13.9	11.9	11.5
Pension and Postretirement Benefit Plans | Reclassification out of Accumulated Other Comprehensive (Loss) Income
Income Statement [Abstract]
Net periodic benefit cost	3.0	2.2	1.8
Benefit for income taxes	(0.8)	(0.5)	(0.4)
Net income (loss) attributable to parent	$ 2.3	$ 1.7	$ 1.4