Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Composition of Loans, Net of Unearned Income (Additional Information) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unearned income on loans	$ 248	$ 226
Loans, at amortized cost	50,754	45,181
Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	509	400
Construction loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	84	118
Private bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	5,297	4,901
Premium wine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	1,002	1,053
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	7	28
Real estate secured loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	5,253	4,940
Real estate secured loans | Private bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	4,412	4,059
Real estate secured loans | Private bank | Loans for personal residence
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	3,773	3,392
Real estate secured loans | Private bank | Loans to eligible employees
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	447	481
Real estate secured loans | Private bank | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	61	43
Real estate secured loans | Private bank | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	131	143
Real estate secured loans | Premium wine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	807	824
Real estate secured loans | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at amortized cost	$ 34	$ 57