Non-vested Award Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock-settled awards
Stock-based Payment Award
Non-vested as of January 1, 2018	4.1
Nonvested as of January 1, 2018, weighted-average grant date fair value	$ 22.82
Granted	1.3
Granted, Weighted-average grant-date fair value	$ 36.36	$ 26.96	$ 20.70
Vested	(1.7)
Vested, Weighted-average grant date fair value	$ 23.25
Forfeited	(0.2)
Forfeited, Weighted-average grant date fair value	$ 24.78
Non-vested as of December 31, 2018	3.5	4.1
Nonvested as of December 31, 2018, weighted-average grant date fair value	$ 27.52	$ 22.82
Total unrecognized compensation expense remaining	$ 39.3
Weighted-average years expected to be recognized over	1 year
Cash-settled awards
Stock-based Payment Award
Non-vested as of January 1, 2018	0.1
Nonvested as of January 1, 2018, weighted-average grant date fair value	$ 21.78
Granted	0.0
Granted, Weighted-average grant-date fair value	$ 36.53	$ 0	$ 21.02
Vested	(0.1)
Vested, Weighted-average grant date fair value	$ 22.83
Forfeited	0.0
Forfeited, Weighted-average grant date fair value	$ 23.46
Non-vested as of December 31, 2018	0.0	0.1
Nonvested as of December 31, 2018, weighted-average grant date fair value	$ 27.96	$ 21.78
Total unrecognized compensation expense remaining	$ 0.6
Weighted-average years expected to be recognized over	10 months 24 days
Cash awards granted during the period target value	$ 19.9	$ 85.8	$ 54.5
Incentive compensation expense, non share-based	$ 42.0	$ 47.8	$ 25.5
Performance-based awards
Stock-based Payment Award
Non-vested as of January 1, 2018	3.3
Nonvested as of January 1, 2018, weighted-average grant date fair value	$ 19.18
Granted	1.6
Granted, Weighted-average grant-date fair value	$ 29.95	$ 21.98	$ 18.67
Vested	(1.5)
Vested, Weighted-average grant date fair value	$ 20.16
Forfeited	(0.5)
Forfeited, Weighted-average grant date fair value	$ 20.91
Non-vested as of December 31, 2018	2.9	3.3
Nonvested as of December 31, 2018, weighted-average grant date fair value	$ 24.31	$ 19.18
Total unrecognized compensation expense remaining	$ 31.7
Weighted-average years expected to be recognized over	2 years
Cash awards granted during the period target value	$ 46.0	$ 40.4	$ 43.5
Incentive compensation expense, non share-based	$ 44.7	$ 52.1	$ 29.2