Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Preferred Stock, end of period	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Treasury Stock, at cost	Treasury Stock, at cost Stock Compensation Plan	Warrant	Accumulated Other Comprehensive Income (Loss), net of tax
Beginning balance at Dec. 31, 2018				$ 4,378	$ 11,055	$ 0	$ 11,055	$ (1,091)			$ (1,579)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under incentive and stock compensation plans				(100)
Stock-based compensation plans expense				114
Issuance of shares for warrant exercise				(80)
Treasury Stock, Retired, Cost Method, Amount				0				0
Net income	$ 2,085				2,085
Dividends declared on preferred stock	(21)				(21)
Dividends declared on common stock					(434)
Treasury stock acquired	(200)							(200)
Stock Issued During Period, Value, Treasury Stock Reissued									$ 135	$ 80
Net shares acquired related to employee incentive and stock compensation plans								(41)
Other Comprehensive Income (Loss), Net of Tax											1,631
Ending balance at Dec. 31, 2019	$ 16,270	$ 334	$ 4	4,312	12,685		12,667	(1,117)			52
Ending balance (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2019						(18)
Preferred Shares Outstanding, end of period at Dec. 31, 2019		13,800,000
Common Shares Outstanding, beginning of period (in thousands) at Dec. 31, 2018			359,151,000
Common Shares Outstanding
Treasury stock acquired	(3,400,000)		(3,412,000)
Issuance of shares under incentive and stock compensation plans			2,906,000
Return of shares under incentive and stock compensation plans to treasury stock			(796,000)
Issuance of shares for warrant exercise			1,721,000
Common Shares Outstanding, end of period at Dec. 31, 2019			359,570,000
Common Shares Outstanding
Cash dividends declared per common share	$ 1.20
Preferred Stock, Dividends Per Share, Declared	$ 1,500
Issuance of shares under incentive and stock compensation plans				(96)
Stock-based compensation plans expense				106
Issuance of shares for warrant exercise				0
Treasury Stock, Retired, Cost Method, Amount				0				0
Net income	$ 1,737				1,737
Dividends declared on preferred stock	(21)				(21)
Dividends declared on common stock					(465)
Treasury stock acquired	(150)							(150)
Stock Issued During Period, Value, Treasury Stock Reissued									112	0
Net shares acquired related to employee incentive and stock compensation plans								(37)
Other Comprehensive Income (Loss), Net of Tax											1,118
Ending balance at Dec. 31, 2020	$ 18,556	$ 334	$ 4	4,322	13,918	$ 0	$ 13,918	(1,192)			1,170
Preferred Shares Outstanding, end of period at Dec. 31, 2020		13,800,000
Common Shares Outstanding
Treasury stock acquired	(2,700,000)		(2,661,000)
Issuance of shares under incentive and stock compensation plans			2,298,000
Return of shares under incentive and stock compensation plans to treasury stock			(718,000)
Issuance of shares for warrant exercise			0
Common Shares Outstanding, end of period at Dec. 31, 2020			358,489,000
Common Shares Outstanding
Cash dividends declared per common share	$ 1.30
Preferred Stock, Dividends Per Share, Declared	$ 1,500
Issuance of shares under incentive and stock compensation plans				(90)
Stock-based compensation plans expense				116
Issuance of shares for warrant exercise				0
Treasury Stock, Retired, Cost Method, Amount				(1,039)				(1,039)
Net income	$ 2,365				2,365
Dividends declared on preferred stock	(21)				(21)
Dividends declared on common stock					(498)
Treasury stock acquired	(1,700)							(1,702)
Stock Issued During Period, Value, Treasury Stock Reissued									$ 146	$ 0
Net shares acquired related to employee incentive and stock compensation plans								(31)
Other Comprehensive Income (Loss), Net of Tax											(998)
Ending balance at Dec. 31, 2021	$ 17,843	$ 334	$ 4	$ 3,309	$ 15,764			$ (1,740)			$ 172
Preferred Shares Outstanding, end of period at Dec. 31, 2021		13,800,000
Common Shares Outstanding
Treasury stock acquired	(25,900,000)		(25,878,000)
Issuance of shares under incentive and stock compensation plans			2,902,000
Return of shares under incentive and stock compensation plans to treasury stock			(587,000)
Issuance of shares for warrant exercise			0
Common Shares Outstanding, end of period at Dec. 31, 2021			334,926,000
Common Shares Outstanding
Cash dividends declared per common share	$ 1.44
Preferred Stock, Dividends Per Share, Declared	$ 1,500