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, 2020	$ 26,200	$ 2,471	$ 504	$ 10,205	$ 23,442	$ 187	$ (10,609)
Beginning balance (shares) at Dec. 31, 2020			503,880				150,723
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	519				519
Other comprehensive income (loss)	(605)					(605)
Preferred stock redeemed	(500)	(495)			(5)
Cash dividends declared:
Common stock dividends	(182)				(182)
Preferred stock cash dividend	(25)				(25)
Common stock acquired (shares)							6,233
Common stock acquired	(475)						$ (475)
Common stock awards exercised	71			22			$ 49
Common stock awards exercised (shares)							(1,111)
Other	2				2
Other (shares)							(2)
Ending balance at Mar. 31, 2021	25,005	1,976	$ 504	10,227	23,751	(418)	$ (11,035)
Ending balance (shares) at Mar. 31, 2021			503,880				155,847
Beginning balance at Dec. 31, 2021	27,363	1,976	$ 504	10,787	25,238	(1,133)	$ (10,009)
Beginning balance (shares) at Dec. 31, 2021			503,880				137,897
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	604				604
Other comprehensive income (loss)	(1,565)					(1,565)
Cash dividends declared:
Common stock dividends	(209)				(209)
Preferred stock cash dividend	(20)				(20)
Common stock awards exercised	66			(11)			$ 77
Common stock awards exercised (shares)							(1,132)
Other	(15)			(14)	(1)
Other (shares)							0
Ending balance at Mar. 31, 2022	$ 26,224	$ 1,976	$ 504	$ 10,762	$ 25,612	$ (2,698)	$ (9,932)
Ending balance (shares) at Mar. 31, 2022			503,880				136,765