Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Recorded Investment in Loans Modified in TDRs within Previous 12 months Subsequently Defaulted (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	$ 998	$ 48,257	$ 998	$ 48,257
Global fund banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	0	0	0
Investor dependent
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	10,963	0	10,963
Investor dependent | Early stage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	0	0	0
Investor dependent | Mid stage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	0	0	0
Investor dependent | Later stage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	10,963	0	10,963
Cash flow dependent
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	37,294	0	37,294
Cash flow dependent | Sponsor led buyout
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	37,294	0	37,294
Cash flow dependent | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	0	0	0
SVB Private Bank
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	0	0	0
Balance sheet dependent
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	0	0	0
Premium wine
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	998	0	998	0
Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	0	0	0	0
SBA loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Recorded investment in loans modified in TDRs	$ 0	$ 0	$ 0	$ 0