Earnings per Share - Calculation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Calculation of basic earnings per share:
Net income applicable to common stock	$ 123.0	$ 85.7	$ 200.5	$ 373.9
Weighted-average common shares outstanding - basic (in shares)	157.6	156.1	163.5	155.9
Basic earnings per share (in dollars per share)	$ 0.78	$ 0.55	$ 1.23	$ 2.40
Calculation of diluted earnings per share:
Net income applicable to common stock	$ 123.0	$ 85.7	$ 200.5	$ 373.9
Convertible Notes	1.8	4.4	5.4	13.0
Diluted income applicable to common stock	$ 124.8	$ 90.1	$ 205.9	$ 386.9
Weighted average common shares outstanding - diluted (in shares)	173.0	172.7	179.0	172.7
Diluted earnings per share (in dollars per share)	$ 0.72	$ 0.52	$ 1.15	$ 2.24
Effective tax rate	226.70%	29.70%	(62.90%)	22.70%
Convertible Notes
Calculation of diluted earnings per share:
Effective tax rate	21.00%	20.00%	21.00%	20.00%
Common Stock, Non-Exchangeable
Calculation of basic earnings per share:
Weighted-average common shares outstanding - basic (in shares)	157.0	156.1	162.9	155.9
Common Stock, Exchangeable
Calculation of basic earnings per share:
Weighted-average common shares outstanding - basic (in shares)	0.6	0.0	0.6	0.0