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, 2016	$ 21,193	$ 3,196	$ 504	$ 9,782	$ 17,433		$ (2,040)		$ (7,682)
Beginning balance (shares) at Dec. 31, 2016			503,880						121,941
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,156				2,156
Other comprehensive income (loss)	1,031						1,031
Cash dividends declared:
Common stock dividends	(596)				(596)
Preferred stock cash dividend	(182)				(182)
Common stock acquired	(1,450)								$ (1,450)
Common stock acquired (shares)									16,788
Common stock awards exercised	120			16					$ 104
Common stock awards exercised (shares)									(2,503)
Other	(2)			1	(2)				$ (1)
Other (shares)									4
Ending balance at Dec. 31, 2017	22,270	3,196	$ 504	9,799	18,809		(1,009)		$ (9,029)
Ending balance (shares) at Dec. 31, 2017			503,880						136,230
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,593				2,593
Other comprehensive income (loss)	(347)						(347)
Preferred stock issued	494	494
Common stock issued	1,150			586					$ 564
Common stock issued (in shares)									(13,244)
Cash dividends declared:
Common stock dividends	(665)				(665)
Preferred stock cash dividend	(188)				(188)
Common stock acquired	(350)								$ (350)
Common stock acquired (shares)									3,324
Common stock awards exercised	145			44					$ 101
Common stock awards exercised (shares)									(2,389)
Other	(365)			(368)	4				$ (1)
Other (shares)									12
Ending balance at Dec. 31, 2018	24,737	3,690	$ 504	10,061	20,553		(1,356)		$ (8,715)
Ending balance (shares) at Dec. 31, 2018			503,880						123,933
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of certain tax effects	(84)				84	[1]	(84)	[1]
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	(1,600)								$ (1,600)
Common stock acquired (shares)									24,884
Common stock awards exercised	198			95					$ 103
Common stock awards exercised (shares)									(2,295)
Other	(22)			(24)	(1)				$ 3
Other (shares)									(32)
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

[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