Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income (Numerator)
Net income	$ 578	$ 544	$ 1,521	$ 1,525
Net income applicable to common stock for computing basic earnings per common share	578	544	1,521	1,525
Net income as adjusted for purposes of computing diluted earnings per common share	$ 578	$ 544	$ 1,521	$ 1,525
Weighted-average number of shares:
Outstanding during period (in shares)	1,034,786	1,079,917	1,031,687	1,095,223
Non-vested restricted stock (in shares)	(21,662)	(17,833)	(20,189)	(18,117)
Weighted average shares outstanding for computing basic earnings per common share (in shares)	1,013,124	1,062,084	1,011,498	1,077,106
Incremental common shares attributable to dilutive securities:
Shares issuable under convertible securities (in shares)	10	10	10	10
Shares issuable under incentive compensation plans (in shares)	3,879	7,063	4,773	6,763
Number of shares as adjusted for purposes of computing diluted earnings per common share (in shares)	1,017,013	1,069,157	1,016,281	1,083,879
Basic earnings per common share (in dollars per share)	$ 0.57	$ 0.51	$ 1.50	$ 1.42
Diluted earnings per common share (in dollars per share)	$ 0.57	$ 0.51	$ 1.50	$ 1.41
Number of shares of common stock excluded from the computation of diluted earnings per share (less than) (in shares)	12,900	3,900	10,400	3,000