Earnings Per Common Share ("EPS") (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net Income		$ 224	$ 391	$ 623	$ 717
Weighted-average common shares outstanding (for basic calculation)		286.0	298.0	288.0	299.0
Effect of dilutive share-based employee compensation		4.0	6.0	4.0	5.0
Weighted-average common and dilutive potential common shares outstanding (for diluted calculation)		290.0	304.0	292.0	304.0
Basic EPS		$ 0.78	$ 1.31	$ 2.16	$ 2.39
Diluted EPS		$ 0.77	$ 1.29	$ 2.13	$ 2.35
Unexercised employee stock options and stock appreciation rights (in millions) excluded from the diluted EPS computation	[1]	2.4	1.5	1.8	2.1

[1] These unexercised employee stock options and stock appreciation rights were not included in the computation of diluted EPS because to do so would have been antidilutive for the periods presented.