Consolidated Statement of Changes In Shareholders' Equity - USD ($) shares in Thousands, $ in Millions		Total	Preferred Stock	Common Stock	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2018		$ 24,737	$ 3,690	$ 504	$ 10,061	$ 20,553	$ (1,356)	$ (8,715)
Beginning balance (shares) at Dec. 31, 2018				503,880				123,933
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of certain tax effects	[1]	0				84	(84)
Net income		2,242				2,242
Other comprehensive income (loss)		564					564
Preferred stock redeemed		(750)	(728)			(22)
Cash dividends declared:
Common stock dividends		(728)				(728)
Preferred stock cash dividend		(210)				(210)
Common stock acquired (shares)								24,884
Common stock acquired		(1,600)						$ (1,600)
Common stock awards exercised (shares)								(2,295)
Common stock awards exercised		198			95			$ 103
Other (shares)								(32)
Other		(22)			(24)	(1)		$ 3
Ending balance at Dec. 31, 2019		24,431	2,962	$ 504	10,132	21,918	(876)	$ (10,209)
Ending balance (shares) at Dec. 31, 2019				503,880				146,490
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		2,420				2,420
Other comprehensive income (loss)		1,063					1,063
Preferred stock redeemed		(500)	(491)			(9)
Cash dividends declared:
Common stock dividends		(734)				(734)
Preferred stock cash dividend		(152)				(152)
Common stock acquired (shares)								6,464
Common stock acquired		(500)						$ (500)
Common stock awards exercised (shares)								(2,233)
Common stock awards exercised		172			72			$ 100
Other (shares)								2
Other		0			1	(1)		$ 0
Ending balance at Dec. 31, 2020		26,200	2,471	$ 504	10,205	23,442	187	$ (10,609)
Ending balance (shares) at Dec. 31, 2020				503,880				150,723
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		2,693				2,693
Other comprehensive income (loss)		(1,320)					(1,320)
Common stock issued (in shares)								(21,724)
Common stock issued		1,900			516			$ 1,384
Preferred stock redeemed		(500)	(495)			(5)
Cash dividends declared:
Common stock dividends		(779)				(779)
Preferred stock cash dividend		(114)				(114)
Common stock acquired (shares)								11,250
Common stock acquired		(900)						$ (900)
Common stock awards exercised (shares)								(2,350)
Common stock awards exercised		164			48			$ 116
Other (shares)								(2)
Other		19			18	1		$ 0
Ending balance at Dec. 31, 2021		$ 27,363	$ 1,976	$ 504	$ 10,787	$ 25,238	$ (1,133)	$ (10,009)
Ending balance (shares) at Dec. 31, 2021				503,880				137,897

[1] Represents the reclassification from accumulated other comprehensive income into retained earnings as a result of our adoption of ASU 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income in the first quarter of 2019.