Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net income (loss)	$ 285.0	$ 452.1
Subtract:
Net income (loss) attributable to noncontrolling interest	(3.9)	22.2
Total	$ 288.9	$ 429.9
Weighted-average shares outstanding:
Basic	275.0	278.7
Dilutive effects:
Diluted	277.2	280.9
Net income (loss) per common share:
Basic	$ 1.05	$ 1.54
Diluted	$ 1.04	$ 1.53
Nonqualified Stock Options
Dilutive effects:
Stock-based compensation awards	0.5	0.7
Restricted Stock Units
Dilutive effects:
Stock-based compensation awards	1.6	1.5
Performance Share Awards
Dilutive effects:
Stock-based compensation awards	0.1