Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Nonaccrual Loans with No Allowance for Credit Loss (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	$ 90,247	$ 104,244
Nonaccrual Loans with no Allowance for Credit Loss	10,755	7,850
Global Fund Banking
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	18	11
Nonaccrual Loans with no Allowance for Credit Loss	8	11
Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	35,169	51,053
Nonaccrual Loans with no Allowance for Credit Loss	6,813	3,280
Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	45,476	46,000
Nonaccrual Loans with no Allowance for Credit Loss	572	1,138
SVB Private Bank
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	8,445	6,152
Nonaccrual Loans with no Allowance for Credit Loss	2,365	2,393
Balance sheet dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	0	0
Nonaccrual Loans with no Allowance for Credit Loss	0	0
Premium wine
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	1,139	998
Nonaccrual Loans with no Allowance for Credit Loss	997	998
Other
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	0	30
Nonaccrual Loans with no Allowance for Credit Loss	0	30
SBA loans
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	0	0
Nonaccrual Loans with no Allowance for Credit Loss	0	0
Early stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	7,766	18,340
Nonaccrual Loans with no Allowance for Credit Loss	376	3
Mid stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	0	4,056
Nonaccrual Loans with no Allowance for Credit Loss	0	3,159
Later stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	27,403	28,657
Nonaccrual Loans with no Allowance for Credit Loss	6,437	118
Sponsor led buyout | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	39,848	39,996
Nonaccrual Loans with no Allowance for Credit Loss	0	0
Other | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	5,628	6,004
Nonaccrual Loans with no Allowance for Credit Loss	$ 572	$ 1,138