Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Nonvoting Common Stock [Member]	Preferred Stock [Member]	Common Stock [Member] Common Stock [Member]	Common Stock [Member] Nonvoting Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock, at cost [Member]	Treasury Stock, at cost [Member] Common Stock [Member]	Treasury Stock, at cost [Member] Nonvoting Common Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at beginning of period at Dec. 31, 2020	$ 56,060			$ 7,733	$ 20	$ 1	$ 26,515	$ 21,975	$ (5,578)			$ 5,394
Beginning balance (in shares) at Dec. 31, 2020					1,995	79
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,275	$ 4,096	$ 179					4,275
Other comprehensive income (loss), net of tax	(4,141)											(4,141)
Issuance of preferred stock, net	2,806			2,806
Redemption or call of preferred stock	(600)			(585)				(15)
Dividends declared on preferred stock	(331)							(331)
Dividends declared on common stock	(1,024)							(1,024)
Stock option exercises and other	162						(5)		167
Share-based compensation	188						188
Other	47						57		(10)
Ending balance (in shares) at Sep. 30, 2021					1,995	79
Balance at end of period at Sep. 30, 2021	57,442			9,954	$ 20	$ 1	26,755	24,880	(5,421)			1,253
Balance at beginning of period at Jun. 30, 2021	57,450			9,954	$ 20	$ 1	26,708	23,809	(5,450)			2,408
Beginning balance (in shares) at Jun. 30, 2021					1,995	79
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,526	1,462	64					1,526
Other comprehensive income (loss), net of tax	(1,155)											(1,155)
Dividends declared on preferred stock	(113)							(113)
Dividends declared on common stock	(342)							(342)
Stock option exercises and other	18						(13)		31
Share-based compensation	43						43
Other	15						17		(2)
Ending balance (in shares) at Sep. 30, 2021					1,995	79
Balance at end of period at Sep. 30, 2021	57,442			9,954	$ 20	$ 1	26,755	24,880	(5,421)			1,253
Balance at beginning of period at Dec. 31, 2021	56,261			9,954	$ 20	$ 1	26,741	25,992	(5,338)			(1,109)
Beginning balance (in shares) at Dec. 31, 2021					1,995	79
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,215	5,014	201					5,215
Other comprehensive income (loss), net of tax	(22,043)											(22,043)
Issuance of preferred stock, net	740			740
Redemption or call of preferred stock	(400)			(397)				(3)
Dividends declared on preferred stock	(374)							(374)
Dividends declared on common stock	(1,179)							(1,179)
Repurchase of stock (in shares)					15	15
Repurchase of stock		(500)	(1,000)							$ (500)	$ (1,000)
Conversion of nonvoting common stock to common stock (in shares)					13	13
Stock option exercises and other	42						(68)		110
Share-based compensation	215						215
Other	64						87		(23)
Ending balance (in shares) at Sep. 30, 2022					2,023	51
Balance at end of period at Sep. 30, 2022	37,041			10,297	$ 20	$ 1	26,975	29,651	(6,751)			(23,152)
Balance at beginning of period at Jun. 30, 2022	44,513			10,694	$ 20	$ 1	26,918	28,174	(5,272)			(16,022)
Beginning balance (in shares) at Jun. 30, 2022					1,995	79
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,020	1,956	64					2,020
Other comprehensive income (loss), net of tax	(7,130)											(7,130)
Redemption or call of preferred stock	(400)			(397)				(3)
Dividends declared on preferred stock	(123)							(123)
Dividends declared on common stock	(417)							(417)
Repurchase of stock (in shares)					15	15
Repurchase of stock		$ (500)	$ (1,000)							$ (500)	$ (1,000)
Conversion of nonvoting common stock to common stock (in shares)					13	13
Stock option exercises and other	9						(12)		21
Share-based compensation	50						50
Other	19						19		0
Ending balance (in shares) at Sep. 30, 2022					2,023	51
Balance at end of period at Sep. 30, 2022	$ 37,041			$ 10,297	$ 20	$ 1	$ 26,975	$ 29,651	$ (6,751)			$ (23,152)