Earnings Per Common Share (EPS) (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
Basic and diluted:
Net income	$ 1,879		$ 1,826		$ 5,942		$ 6,341
Preferred dividends	(14)		(20)		(43)		(49)
Equity-related adjustment	0		(9)		0		(9)
Net income available to common shareholders	1,865		1,797		5,899		6,283
Earnings allocated to participating share awards	(14)		(14)		(45)		(45)
Net income attributable to common shareholders	$ 1,851		$ 1,783		$ 5,854		$ 6,238
Denominator:
Basic: Weighted-average common stock (in shares)	748,000		786,000		752,000		796,000
Add: Weighted-average stock options (in shares)	1,000		1,000		1,000		1,000
Diluted (in shares)	749,000		787,000		753,000		797,000
Basic EPS (in dollars per share)	$ 2.47	[1]	$ 2.27	[1]	$ 7.78	[2]	$ 7.84	[2]
Diluted EPS (in dollars per share)	$ 2.47	[1]	$ 2.27	[1]	$ 7.77	[2]	$ 7.82	[2]
Stock options
Denominator:
The dilutive effect of securities excluded from the calculation of earnings per share (in shares)	260		10		230		10

[1] Represents net income less (i) earnings allocated to participating share awards of $14 million for both the three months ended September 30, 2022 and 2021, (ii) dividends on preferred shares of $14 million and $20 million for the three months ended September 30, 2022 and 2021, respectively, and (iii) an equity-related adjustment of $9 million related to the redemption of preferred shares for the three months ended September 30, 2021.

[2] Represents net income less (i) earnings allocated to participating share awards of $45 million for both the nine months ended September 30, 2022 and 2021, (ii) dividends on preferred shares of $43 million and $49 million for the nine months ended September 30, 2022 and 2021, respectively, and (iii) an equity-related adjustment of $9 million related to the redemption of preferred shares for the nine months ended September 30, 2021.