Earnings Per Share - Summary of Basic and Diluted Earnings Per Share and Antidilutive Securities Excluded From Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator:
Income from continuing operations	$ 216.9	$ 233.3	$ 527.2	$ 705.0
Less: dividends declared	42.2	39.1	119.5	95.8
Undistributed earnings	$ 174.7	$ 194.2	$ 407.7	$ 609.2
Percent allocated to common stockholders	99.80%	99.80%	99.80%	99.80%
Undistributed earnings allocated to common stockholders	$ 174.3	$ 193.7	$ 406.7	$ 607.7
Add: dividends declared to common shares, restricted share units and vested and deferred restricted and performance shares	42.1	39.0	119.3	95.6
Income from continuing operations attributable to common stockholders	$ 216.4	$ 232.7	$ 526.0	$ 703.3
Shares:
Basic weighted-average shares outstanding (in shares)	49.5	51.9	50.4	51.9
Effect of dilutive securities:
Performance awards (in shares)	0.2	0.2	0.2	0.2
Stock options (in shares)	0.4	0.5	0.4	0.5
Diluted weighted-average shares outstanding (in shares)	50.1	52.6	51.0	52.6
Per share income from continuing operations attributable to common shares:
Basic (in dollars per share)	$ 4.37	$ 4.49	$ 10.43	$ 13.55
Diluted (in dollars per share)	$ 4.32	$ 4.42	$ 10.32	$ 13.35
Basic weighted-average shares outstanding (in shares)	49.5	51.9	50.4	51.9
Basic weighted-average shares outstanding and unvested restricted shares expected to vest (in shares)	49.6	52.0	50.6	52.0
Percent allocated to common stockholders	99.80%	99.80%	99.80%	99.80%
Anti-dilutive stock options excluded from EPS calculation
Income from discontinued operations attributable to common stockholders for basic earnings per share	$ 48.6	$ 21.3	$ 34.7	$ 44.7
Income from discontinued operations attributable to common stockholder for diluted earnings per share	48.6	21.3	34.7	44.7
Net income attributable to common stockholders for basic earnings per share	264.9	254.1	560.5	748.0
Net income attributable to common stockholders for diluted earnings per share	$ 264.9	$ 254.1	$ 748.0	$ 560.5
Anti-dilutive stock options excluded from earnings per share calculation (in shares)	0.6	0.0	0.7	0.1