Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net income (loss)	$ 416.1	$ 392.1	$ 701.1	$ 844.2
Subtract:
Net income (loss) attributable to noncontrolling interest	17.8	5.8	13.9	28.0
Total	$ 398.3	$ 386.3	$ 687.2	$ 816.2
Weighted-average shares outstanding:
Basic	274.3	279.0	274.6	278.8
Dilutive effects:
Diluted	275.6	281.2	276.4	281.2
Net income (loss) per common share:
Basic	$ 1.45	$ 1.38	$ 2.50	$ 2.93
Diluted	$ 1.45	$ 1.37	$ 2.49	$ 2.90
Nonqualified Stock Options
Dilutive effects:
Stock-based compensation awards	0.1	0.9	0.3	0.9
Restricted Stock Units
Dilutive effects:
Stock-based compensation awards	1.1	1.2	1.4	1.3
Performance Share Awards
Dilutive effects:
Stock-based compensation awards	0.1	0.1	0.1	0.2