Credit Quality and the Allowance for Loan and Lease Losses - Summary of Transactions in the ALLL by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2022		Jun. 30, 2021	Jun. 30, 2022		Jun. 30, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 1,908		$ 2,208	$ 1,892	[1]	$ 2,453
Losses charged-off	(90)		(103)	(154)		(211)
Recoveries of losses previously charged-off	28		59	58		96
(Benefit from) provision for loan and lease losses	168		(131)	218		(305)
Balance, end of period	2,014	[1]	2,033	2,014	[1]	2,033
Other Consumer Loans, Point of Sale
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Losses charged-off	(7)		(8)	(15)		(18)
Recoveries of losses previously charged-off	7		8	15		18
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,110		1,329	1,102		1,456
Losses charged-off	(37)		(45)	(48)		(81)
Recoveries of losses previously charged-off	1		28	4		35
(Benefit from) provision for loan and lease losses	91		(88)	107		(186)
Balance, end of period	1,165		1,224	1,165		1,224
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	239		247	235		294
Losses charged-off	0		(1)	(1)		(2)
Recoveries of losses previously charged-off	1		1	2		3
(Benefit from) provision for loan and lease losses	8		(12)	12		(60)
Balance, end of period	248		235	248		235
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	559		632	555		703
Losses charged-off	(53)		(57)	(105)		(128)
Recoveries of losses previously charged-off	26		30	52		58
(Benefit from) provision for loan and lease losses	69		(31)	99		(59)
Balance, end of period	$ 601		$ 574	$ 601		$ 574

[1] Includes $21 and $24 of other short-term investments, $267 and $322 of portfolio loans and leases, $(3) and $(2) of ALLL, $2 and $2 of other assets, $10 and $1 of other liabilities, and $200 and $263 of long-term debt from consolidated VIEs that are included in their respective captions above at June 30, 2022 and December 31, 2021, respectively. For further information, refer to Note 12.