Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Income from continuing operations	$ 194.3	$ 49.1
Less: dividends declared	(28.7)	(28.5)
Undistributed earnings	$ 165.6	$ 20.6
Percent allocated to common stockholders	99.70%	99.70%
Undistributed earnings available to common shareholders	$ 165.1	$ 20.5
Add: dividends declared to common shares, restricted share units and vested and deferred restricted and performance shares	28.7	28.4
Income from continuing operations attributable to common stockholders	$ 193.8	$ 48.9
Denominator (in thousands):
Basic weighted-average shares outstanding (in shares)	52.1	53.0
Effect of dilutive securities:
Performance awards (in shares)	0.2	0.1
Stock options (in shares)	0.6	0.5
Denominator for diluted EPS: weighted-average shares outstanding (in shares)	52.9	53.6
Per share income from continuing operations attributable to common shares:
Basic (in dollars per share)	$ 3.72	$ 0.92
Diluted (in dollars per share)	$ 3.67	$ 0.91
Basic weighted-average shares outstanding (in shares)	52.1	53.0
Basic weighted-average shares outstanding and unvested restricted shares expected to vest (in shares)	52.3	53.2
Percent allocated to common stockholders	99.70%	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	$ (0.7)	$ 3.1
Net income attributable to common stockholders for basic and diluted earnings per share	$ 193.1	$ 52.0
Anti-dilutive stock options excluded from earnings per share calculation (in shares)	0.1	0.6