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
Ending balance (shares) at Mar. 31, 2019			1,488
Ending balance at Mar. 31, 2019	21,625	2,793	$ 15	4,548	18,017	(3,677)	(71)
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	1,901				1,901
Other comprehensive income (loss), net of tax	351						351
Dividends declared on preferred stock	(81)				(81)
Dividends declared on common stock	(456)				(456)
Repurchase of common stock	(1,220)					(1,220)
Stock option exercises and other	48			(13)		61
Share-based compensation	88			88
Other	19			25	(13)	7
Ending balance (shares) at Jun. 30, 2019			1,488
Ending balance at Jun. 30, 2019	21,320	2,793	$ 15	4,599	18,680	(4,866)	99
Beginning balance at Mar. 31, 2019	21,625	2,793	$ 15	4,548	18,017	(3,677)	(71)
Beginning balance (shares) at Mar. 31, 2019			1,488
Increase (Decrease) in Stockholders' Equity
Net income	937				937
Other comprehensive income (loss), net of tax	170						170
Dividends declared on preferred stock	(47)				(47)
Dividends declared on common stock	(228)				(228)
Repurchase of common stock	(1,220)					(1,220)
Stock option exercises and other	22			1		21
Share-based compensation	35			35
Other	26			15	1	10
Ending balance (shares) at Jun. 30, 2019			1,488
Ending balance at Jun. 30, 2019	21,320	2,793	$ 15	4,599	18,680	(4,866)	99
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	1,466				1,466
Other comprehensive income (loss), net of tax	5,523						5,523
Issuance of preferred stock, net	2,470	2,470
Dividends declared on preferred stock	(81)				(81)
Dividends declared on common stock	(466)				(466)
Stock option exercises and other	29			(10)		39
Share-based compensation	91			91
Other	38			23	(3)	18
Ending balance (shares) at Jun. 30, 2020			1,488
Ending balance at Jun. 30, 2020	30,815	5,263	$ 15	4,760	20,876	(5,710)	5,611
Beginning balance at Mar. 31, 2020	26,270	2,793	$ 15	4,714	20,487	(5,734)	3,995
Beginning balance (shares) at Mar. 31, 2020			1,488
Increase (Decrease) in Stockholders' Equity
Net income	671				671
Other comprehensive income (loss), net of tax	1,616						1,616
Issuance of preferred stock, net	2,470	2,470
Dividends declared on preferred stock	(47)				(47)
Dividends declared on common stock	(233)				(233)
Stock option exercises and other	6			(2)		8
Share-based compensation	35			35
Other	27			13	(2)	16
Ending balance (shares) at Jun. 30, 2020			1,488
Ending balance at Jun. 30, 2020	$ 30,815	$ 5,263	$ 15	$ 4,760	$ 20,876	$ (5,710)	$ 5,611