Parent Company (Statement of Cash Flows) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Other		$ (194)	$ 684	$ (341)
Net cash provided (used) by operating activities		7,214	4,659	7,363
Investing Activities
Securities available for sale		26,329	13,851	7,755
Net cash paid for acquisition	[1]	(10,511)
Other		(2,682)	(1,264)	(705)
Net cash provided (used) by investing activities		(2,795)	(51,122)	(24,990)
Financing Activities
Preferred stock issuances		1,484
Preferred stock redemptions			(480)
Acquisition of treasury stock		(1,079)	(1,624)	(3,578)
Preferred stock cash dividends paid		(233)	(229)	(236)
Common stock cash dividends paid		(2,056)	(1,980)	(1,895)
Net Increase (Decrease) In Cash And Due From Banks And Restricted Cash		987	1,956	(547)
Net cash provided by discontinued operations			11,542	299
Net cash provided (used) by continuing operations		987	(9,586)	(846)
Cash and due from banks and restricted cash at beginning of period		7,017	5,061	5,608
Cash and due from banks and restricted cash at end of period		8,004	7,017	5,061
Parent Company
Operating Activities
Net income		5,673	7,517	5,369
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Equity in undistributed net earnings of subsidiaries		(1,628)		(1,363)
Return on investment in subsidiaries			6,444
Other		(248)	237	218
Net cash provided (used) by operating activities		3,797	14,198	4,224
Investing Activities
Securities available for sale		300
Net change in loans and securities from affiliates		(1,188)	(2,808)	664
Net change in nonrestricted interest-earning deposits			7,024	(2,369)
Net cash paid for acquisition		(11,358)
Other		(5)		(8)
Net cash provided (used) by investing activities		(12,251)	4,216	(1,713)
Financing Activities
Net change in other borrowed funds from affiliates		(435)	473	228
Proceeds from long-term borrowings		1,692	1,986	4,180
Repayments of long-term borrowings		(500)	(1,750)	(1,300)
Preferred stock issuances		1,484
Preferred stock redemptions			(480)
Common and treasury stock issuances		66	65	90
Acquisition of treasury stock		(1,079)	(1,624)	(3,578)
Preferred stock cash dividends paid		(233)	(229)	(236)
Common stock cash dividends paid		(2,056)	(1,979)	(1,895)
Net cash provided (used) by financing activities		(1,061)	(3,538)	(2,511)
Net Increase (Decrease) In Cash And Due From Banks And Restricted Cash		(9,515)	14,876
Net cash provided by discontinued operations			11,542	299
Net cash provided (used) by continuing operations		(9,515)	3,334	(299)
Cash and due from banks and restricted cash at beginning of period		15,057	181	181
Cash and due from banks and restricted cash at end of period		$ 5,542	$ 15,057	$ 181

[1] Cash paid to acquire BBVA was $11,480 million. The amount of $10,511 million represents the cash paid for the acquisition less $969 million in cash acquired. See Note 2 Acquisition & Divestiture Activity for more detailed information on the BBVA acquisition.