Credit Quality and the Allowance for Loan and Lease Losses - Summary of Transactions in the ALLL by Portfolio Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 2,453	[1]	$ 1,202		$ 1,103
Losses charged-off	(344)		(611)		(510)
Recoveries of losses previously charged-off	170		140		141
Provision for (benefit from) loan and lease losses	(387)		1,079		468
Balance, end of period	1,892	[1]	2,453	[1]	1,202
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period			643
Balance, end of period					643
Other Consumer Loans, Point of Sale
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Losses charged-off	(33)		(42)		(48)
Recoveries of losses previously charged-off	33		42		48
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,456		710		645
Losses charged-off	(119)		(282)		(127)
Recoveries of losses previously charged-off	52		16		19
Provision for (benefit from) loan and lease losses	(287)		852		173
Balance, end of period	1,102		1,456		710
Initial recognition of ALLL on PCD loans			31
Commercial | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period			160
Balance, end of period					160
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	294		73		81
Losses charged-off	(3)		(9)		(9)
Recoveries of losses previously charged-off	7		7		5
Provision for (benefit from) loan and lease losses	(63)		27		(4)
Balance, end of period	235		294		73
Initial recognition of ALLL on PCD loans			2
Residential Mortgage | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period			196
Balance, end of period					196
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	703		298		267
Losses charged-off	(222)		(320)		(374)
Recoveries of losses previously charged-off	111		117		117
Provision for (benefit from) loan and lease losses	(37)		200		288
Balance, end of period	555		703		298
Initial recognition of ALLL on PCD loans			1
Consumer | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period			408
Balance, end of period					408
Unallocated
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 0		121		110
Losses charged-off			0		0
Recoveries of losses previously charged-off			0		0
Provision for (benefit from) loan and lease losses			0		11
Balance, end of period			0		121
Unallocated | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period			$ (121)
Balance, end of period					$ (121)

[1] Includes $24 and $55 of other short-term investments, $322 and $756 of portfolio loans and leases, $(2) and $(7) of ALLL, $2 and $5 of other assets, $1 and $2 of other liabilities and $263 and $656 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2021 and 2020, respectively. For further information, refer to Note 12.