Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock, at cost [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2018	$ 20,670	$ 2,793	$ 15	$ 4,499	$ 17,329	$ (3,714)	$ (252)
Beginning balance (shares) at Dec. 31, 2018			1,488
Increase (Decrease) in Stockholders' Equity
Net income	2,852				2,852
Other comprehensive income (loss), net of tax	396						396
Dividends declared on preferred stock	(115)				(115)
Dividends declared on common stock	(679)				(679)
Repurchase of common stock	(1,991)					(1,991)
Stock option exercises and other	65			(15)		80
Share-based compensation	121			121
Other	35			35	(13)	13
Ending balance (shares) at Sep. 30, 2019			1,488
Ending balance at Sep. 30, 2019	21,354	2,793	$ 15	4,640	19,374	(5,612)	144
Beginning balance at Jun. 30, 2019	21,320	2,793	$ 15	4,599	18,680	(4,866)	99
Beginning balance (shares) at Jun. 30, 2019			1,488
Increase (Decrease) in Stockholders' Equity
Net income	951				951
Other comprehensive income (loss), net of tax	45						45
Dividends declared on preferred stock	(34)				(34)
Dividends declared on common stock	(223)				(223)
Repurchase of common stock	(771)					(771)
Stock option exercises and other	17			(2)		19
Share-based compensation	33			33
Other	16			10	0	6
Ending balance (shares) at Sep. 30, 2019			1,488
Ending balance at Sep. 30, 2019	21,354	2,793	$ 15	4,640	19,374	(5,612)	144
Beginning balance at Dec. 31, 2019	21,745	2,793	$ 15	4,656	19,960	(5,767)	88
Beginning balance (shares) at Dec. 31, 2019			1,488
Increase (Decrease) in Stockholders' Equity
Net income	2,164				2,164
Other comprehensive income (loss), net of tax	5,598						5,598
Issuance of preferred stock, net	2,470	2,470
Dividends declared on preferred stock	(160)				(160)
Dividends declared on common stock	(700)				(700)
Stock option exercises and other	35			(13)		48
Share-based compensation	123			123
Other	56			31	(3)	28
Ending balance (shares) at Sep. 30, 2020			1,488
Ending balance at Sep. 30, 2020	31,331	5,263	$ 15	4,797	21,261	(5,691)	5,686
Beginning balance at Jun. 30, 2020	30,815	5,263	$ 15	4,760	20,876	(5,710)	5,611
Beginning balance (shares) at Jun. 30, 2020			1,488
Increase (Decrease) in Stockholders' Equity
Net income	698				698
Other comprehensive income (loss), net of tax	75						75
Dividends declared on preferred stock	(79)				(79)
Dividends declared on common stock	(234)				(234)
Stock option exercises and other	6			(3)		9
Share-based compensation	32			32
Other	18			8	0	10
Ending balance (shares) at Sep. 30, 2020			1,488
Ending balance at Sep. 30, 2020	$ 31,331	$ 5,263	$ 15	$ 4,797	$ 21,261	$ (5,691)	$ 5,686