Common, Preferred and Treasury Stock - Share Activity within Common, Preferred and Treasury Stock (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Value
Beginning balance	$ 23,111	$ 21,203	$ 16,250
Shares acquired for treasury	(1,393)		(1,763)
Impact of MB Financial, Inc. acquisition			3,356
Other	(1)	0	4
Ending balance	22,210	23,111	21,203
Common Stock
Value
Beginning balance	2,051	2,051	2,051
Ending balance	$ 2,051	$ 2,051	$ 2,051
Shares
Beginning balance (in shares)	923,892,581	923,892,581	923,892,581
Ending balance (in shares)	923,892,581	923,892,581	923,892,581
Preferred Stock
Value
Beginning balance	$ 2,116	$ 1,770	$ 1,331
Issuance of preferred shares		346	242
Conversion of outstanding preferred stock issued by a Bancorp subsidiary			197
Ending balance	$ 2,116	$ 2,116	$ 1,770
Shares
Beginning balance (in shares)	278,000	264,000	54,000
Issuance of preferred shares (in shares)		14,000	10,000
Conversion of outstanding preferred stock issued by a Bancorp subsidiary (in shares)			200,000
Ending balance (in shares)	278,000	278,000	264,000
Treasury Stock
Value
Beginning balance	$ (5,676)	$ (5,724)	$ (6,471)
Shares acquired for treasury	(1,393)		(1,763)
Impact of MB Financial, Inc. acquisition			2,447
Impact of stock transactions under stock compensation plans, net	44	46	56
Other	1	2	7
Ending balance	$ (7,024)	$ (5,676)	$ (5,724)
Shares
Beginning balance (in shares)	211,132,256	214,976,952	277,261,724
Shares acquired for treasury (in shares)	35,652,079		64,601,891
Impact of MB Financial, Inc. acquisition (in shares)			(122,848,442)
Impact of stock transactions under stock compensation plans, net (in shares)	(5,621,878)	(3,818,518)	(4,258,132)
Other (in shares)	(47,540)	(26,178)	219,911
Ending balance (in shares)	241,114,917	211,132,256	214,976,952