Earnings Per Common Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2023		Jun. 30, 2022		Jun. 30, 2023		Jun. 30, 2022
Basic and diluted:
Net income	$ 2,174		$ 1,964		$ 3,990		$ 4,063
Preferred dividends	(15)		(15)		(29)		(29)
Net income available to common shareholders	2,159		1,949		3,961		4,034
Earnings allocated to participating share awards	(17)		(15)		(31)		(31)
Net income attributable to common shareholders	$ 2,142		$ 1,934		$ 3,930		$ 4,003
Denominator:
Basic: Weighted-average common stock (in shares)	740,000		752,000		741,000		755,000
Add: Weighted-average stock options (in shares)	1,000		1,000		1,000		1,000
Diluted (in shares)	741,000		753,000		742,000		756,000
Basic EPS (in dollars per share)	$ 2.89	[1]	$ 2.57	[1]	$ 5.30	[2]	$ 5.30	[2]
Diluted EPS (in dollars per share)	$ 2.89	[1]	$ 2.57	[1]	$ 5.29	[2]	$ 5.30	[2]
Stock options
Denominator:
The dilutive effect of securities excluded from the calculation of earnings per share (in shares)	1,400		250		1,400		210

[1] Represents net income less (i) earnings allocated to participating share awards of $17 million and $15 million for the three months ended June 30, 2023 and 2022, respectively, and (ii) dividends on preferred shares of $15 million for both the three months ended June 30, 2023 and 2022.

[2] Represents net income less (i) earnings allocated to participating share awards of $31 million for both the six months ended June 30, 2023 and 2022, and (ii) dividends on preferred shares of $29 million for both the six months ended June 30, 2023 and 2022.