Loans and Leases - Schedule of Loans by Class (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 133,202	$ 70,781	$ 69,790
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	58,050	53,455
Commercial | Commercial construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,382	2,804
Commercial | Owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	15,230	14,473
Commercial | Non-owner occupied commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	10,941	9,902
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	26,389	24,105
Commercial | Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	2,108	2,171
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	18,288	17,326
Consumer | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	14,287	13,309
Consumer | Revolving mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,909	1,951
Consumer | Consumer auto
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,411	1,414
Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	681	652
SVB
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	56,864	0
SVB | Global fund banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	27,516	0
SVB | Investor dependent - early stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,718	0
SVB | Investor dependent - growth stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,948	0
SVB | Innovation C&I and cash flow dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	8,724	0
SVB | Private Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	9,648	0
SVB | CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	2,629	0
SVB | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 2,681	$ 0