Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share [Abstract]
Net income	$ 960	$ 2,403
Dividends and undistributed earnings allocated to participating securities	(16)	(28)
Preferred stock dividends	(57)	(57)
Net income available to common stockholders	$ 887	$ 2,318
Total weighted-average basic common shares outstanding	382.6	410.4
Effect of dilutive securities:
Stock options	0.1	0.5
Other contingently issuable shares	1.1	1.3
Total effect of dilutive securities	1.2	1.8
Total weighted Average Number of Shares Outstanding, Diluted, Total	383.8	412.2
Basic earnings per common share:
Net income per basic common share	$ 2.32	$ 5.65
Diluted earnings per common share:
Net income per diluted common share	$ 2.31	$ 5.62