Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Series B Preferred Stock	Series C Preferred Stock	Series D Preferred Stock	Preferred Shares	Common Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained Earnings Series B Preferred Stock	Retained Earnings Series C Preferred Stock	Retained Earnings Series D Preferred Stock
Beginning Balance at Dec. 31, 2020	$ 22,984				$ 0	$ 161	$ 11,881	$ (2,895)	$ 13,837
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,060								8,060
Other comprehensive income (loss)	(50)							(50)
Preferred shares issued	1,584						1,584
Redemption of preferred shares	(1,600)						(1,584)		(16)
Repurchase of common shares	(7,598)					(9)	(631)		(6,958)
Other changes, primarily employee plans	227					1	245		(19)
Cash dividends declared preferred		$ (27)	$ (23)	$ (21)						$ (27)	$ (23)	$ (21)
Cash dividends declared common	(1,359)								(1,359)
Ending Balance at Dec. 31, 2021	22,177				0	153	11,495	(2,945)	13,474
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	7,514								7,514
Other comprehensive income (loss)	(265)							(265)
Repurchase of common shares	(3,332)					(4)	(302)		(3,026)
Other changes, primarily employee plans	242						300		(58)
Cash dividends declared preferred				(57)								(57)
Cash dividends declared common	(1,568)								(1,568)
Ending Balance at Dec. 31, 2022	24,711				0	149	11,493	(3,210)	16,279
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,374								8,374
Other comprehensive income (loss)	138							138
Repurchase of common shares	(3,519)					(4)	(334)		(3,181)
Other changes, primarily employee plans	181						213		(32)
Cash dividends declared preferred				$ (58)								$ (58)
Cash dividends declared common	(1,770)								(1,770)
Ending Balance at Dec. 31, 2023	$ 28,057				$ 0	$ 145	$ 11,372	$ (3,072)	$ 19,612