Share-based Compensation Awards (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-based Payment Award
Vesting period in which the fair value of shares on grant date is amortized over, years	2 years
Stock-settled awards
Stock-based Payment Award
Awards granted	1.4	1.3	0.9
Weighted-average grant-date fair value (per award)	$ 35.54	$ 36.36	$ 26.96
Total fair value of vested awards distributed	$ 60.8	$ 59.7	$ 50.8
Accrued dividends on non-vested stock-settled awards	3.0	3.7
Dividends paid for stock-settled awards	$ 5.3	$ 4.9
Cash-settled awards
Stock-based Payment Award
Awards granted	0.0	0.0	0.0
Weighted-average grant-date fair value (per award)	$ 35.71	$ 36.53	$ 0.0
Total fair value of vested awards distributed	$ 0.8	$ 0.8	$ 0.7
Performance-based awards
Stock-based Payment Award
Awards granted	2.1	1.6	0.5
Weighted-average grant-date fair value (per award)	$ 26.31	$ 29.95	$ 21.98
Total fair value of vested awards distributed	$ 84.8	$ 54.5	$ 39.3