Allowance for Credit Losses - Rollforward of Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 670	$ 963	$ 200
Charge-offs	(93)	(59)	(156)
Recoveries	34	57	36
Provision for credit losses	95	(310)	503
Ending balance	685	670	963	$ 200
Loans and leases	58,102	54,859
Accounting Standards Update [Extensible List]				Accounting Standards Update 2016-13 [Member]
Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			107
Ending balance				$ 107
Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			307
Ending balance				307
Financial Asset Acquired with Credit Deterioration
Allowance for Loan and Lease Losses [Roll Forward]
Additions in allowance for credit loss			287
Funded and Unfunded Loan Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	736	1,048
Ending balance	772	736	1,048
Funded Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Initial allowance on loans purchased with credit deterioration			287
Provision for credit losses	74	(291)	489
Unfunded Commitment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	66	85	6
Initial reserve on loans acquired			41
Provision for credit losses	21	(19)	14
Ending balance	87	66	85	6
Unfunded Commitment | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			24
Ending balance				24
Unfunded Commitment | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			30
Ending balance				30
Commercial | C&I
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	334	453	123
Charge-offs	(62)	(34)	(129)
Recoveries	9	21	9
Ending balance	308	334	453	123
Loans and leases	31,781	31,068
Commercial | C&I | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			19
Ending balance				19
Commercial | C&I | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			142
Ending balance				142
Commercial | C&I | PCD Loans
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs			(237)
Commercial | C&I | Non-PCD Loans
Allowance for Loan and Lease Losses [Roll Forward]
Provision for credit losses			147
Commercial | C&I | Paycheck Protection Plan
Allowance for Loan and Lease Losses [Roll Forward]
Loans and leases	76	1,000
Commercial | C&I | Funded and Unfunded Loan Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	380	518
Ending balance	363	380	518
Commercial | C&I | Funded Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Initial allowance on loans purchased with credit deterioration			138
Provision for credit losses	27	(106)	293
Commercial | C&I | Unfunded Commitment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	46	65	4
Initial reserve on loans acquired			12
Provision for credit losses	9	(19)	32
Ending balance	55	46	65	4
Commercial | C&I | Unfunded Commitment | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			17
Ending balance				17
Commercial | C&I | Unfunded Commitment | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			21
Ending balance				21
Commercial | Commercial Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	154	242	36
Charge-offs	(1)	(5)	(5)
Recoveries	1	5	4
Ending balance	146	154	242	36
Loans and leases	13,228	12,109
Commercial | Commercial Real Estate | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			(7)
Ending balance				(7)
Commercial | Commercial Real Estate | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			29
Ending balance				29
Commercial | Commercial Real Estate | Funded and Unfunded Loan Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	166	252
Ending balance	168	166	252
Commercial | Commercial Real Estate | Funded Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Initial allowance on loans purchased with credit deterioration			100
Provision for credit losses	(8)	(88)	114
Commercial | Commercial Real Estate | Unfunded Commitment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	12	10	2
Initial reserve on loans acquired			26
Provision for credit losses	10	2	(19)
Ending balance	22	12	10	2
Commercial | Commercial Real Estate | Unfunded Commitment | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			1
Ending balance				1
Commercial | Commercial Real Estate | Unfunded Commitment | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			3
Ending balance				3
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Loans and leases	12,253	10,772
Consumer | Consumer real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	163	242	28
Charge-offs	(5)	(5)	(8)
Recoveries	19	27	18
Ending balance	200	163	242	28
Loans and leases	12,253	10,772
Consumer | Consumer real estate | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			93
Ending balance				93
Consumer | Consumer real estate | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			121
Ending balance				121
Consumer | Consumer real estate | Funded and Unfunded Loan Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	171	252
Ending balance	210	171	252
Consumer | Consumer real estate | Funded Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Initial allowance on loans purchased with credit deterioration			44
Provision for credit losses	23	(101)	67
Consumer | Consumer real estate | Unfunded Commitment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	8	10	0
Initial reserve on loans acquired			3
Provision for credit losses	2	(2)	1
Ending balance	10	8	10	0
Consumer | Consumer real estate | Unfunded Commitment | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			6
Ending balance				6
Consumer | Consumer real estate | Unfunded Commitment | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			6
Ending balance				6
Consumer | Credit card and other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	19	26	13
Charge-offs	(25)	(15)	(14)
Recoveries	5	4	5
Ending balance	31	19	26	13
Loans and leases	840	910
Consumer | Credit card and other | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			2
Ending balance				2
Consumer | Credit card and other | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			15
Ending balance				15
Consumer | Credit card and other | Funded and Unfunded Loan Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	19	26
Ending balance	31	19	26
Consumer | Credit card and other | Funded Commitments
Allowance for Loan and Lease Losses [Roll Forward]
Initial allowance on loans purchased with credit deterioration			5
Provision for credit losses	32	4	15
Consumer | Credit card and other | Unfunded Commitment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	0	0
Initial reserve on loans acquired			0
Provision for credit losses	0	0	0
Ending balance	$ 0	$ 0	0	0
Consumer | Credit card and other | Unfunded Commitment | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			0
Ending balance				0
Consumer | Credit card and other | Unfunded Commitment | Adjusted Balance
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ 0
Ending balance				$ 0