Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Numerator:
Income from continuing operations	$ 241.5	$ 290.8	$ 333.3	$ 481.2
Less: dividends declared	38.3	28.0	77.3	56.7
Undistributed earnings	$ 203.2	$ 262.8	$ 256.0	$ 424.5
Percent allocated to common stockholders	99.80%	99.70%	99.80%	99.70%
Undistributed earnings allocated to common stockholders	$ 202.8	$ 262.1	$ 255.5	$ 423.4
Add: dividends declared to common shares, restricted share units and vested and deferred restricted and performance shares	38.2	27.9	77.1	56.6
Income from continuing operations attributable to common stockholders	$ 241.0	$ 290.0	$ 332.6	$ 480.0
Shares:
Basic weighted-average shares outstanding (in shares)	50.7	51.8	50.9	52.0
Effect of dilutive securities:
Performance awards (in shares)	0.2	0.2	0.1	0.2
Stock options (in shares)	0.3	0.5	0.4	0.5
Diluted weighted-average shares outstanding (in shares)	51.2	52.5	51.4	52.7
Per share income from continuing operations attributable to common shares:
Basic (in dollars per share)	$ 4.75	$ 5.60	$ 6.53	$ 9.23
Diluted (in dollars per share)	$ 4.71	$ 5.52	$ 6.47	$ 9.11
Basic weighted-average shares outstanding (in shares)	50.7	51.8	50.9	52.0
Basic weighted-average shares outstanding and unvested restricted shares expected to vest (in shares)	50.8	51.9	51.0	52.1
Percent allocated to common stockholders	99.80%	99.70%	99.80%	99.70%
Anti-dilutive stock options excluded from EPS calculation
(Loss) income from discontinued operations attributable to common stockholders for basic and diluted earnings per share	$ (46.8)	$ 10.7	$ (36.8)	$ 13.9
Net income attributable to common stockholders for basic and diluted earnings per share	$ 194.1	$ 300.8	$ 295.6	$ 493.9
Anti-dilutive stock options excluded from earnings per share calculation (in shares)	0.8	0.2	0.8	0.2