Earnings Per Share (Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income from continuing operations	$ 361.7			$ 182.6			$ 986.1	$ 230.3
Loss from discontinued operations, net of income taxes	0.0			0.0			(0.2)	(0.2)
NET INCOME	$ 361.7	$ 384.8	$ 239.4	$ 182.6	$ 279.8	$ (232.3)	$ 985.9	$ 230.1
Basic weighted average common shares outstanding (in shares)	69.9			88.3			77.3	88.8
Dilutive effect of stock options and unvested RSUs (in shares)	0.8			0.6			0.8	0.2
Diluted weighted average common shares outstanding (in shares)	70.7			88.9			78.1	89.0
Basic EPS amounts:
Continuing operations (in dollars per share)	$ 5.17			$ 2.07			$ 12.76	$ 2.59
Discontinued operations (in dollars per share)	0			0			0	0
Net income (in dollars per share)	5.17			2.07			12.75	2.59
Diluted EPS amounts:
Continuing operations (in dollars per share)	5.12			2.05			12.63	2.59
Discontinued operations (in dollars per share)	0			0			0	0
Net income (in dollars per share)	$ 5.12			$ 2.05			$ 12.62	$ 2.59