Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Nonaccrual Loans with No Allowance for Credit Loss (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	$ 94,326	$ 50,607	$ 102,669	$ 96,641	$ 133,623	$ 94,142
Nonaccrual Loans with no Allowance for Credit Loss	7,956		7,230
Private equity/venture capital
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	9	0	0	0	5,947	3,700
Nonaccrual Loans with no Allowance for Credit Loss	9		0
Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	43,039	45,037	34,719	77,335	63,936	23,752
Nonaccrual Loans with no Allowance for Credit Loss	372		734
Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	26,975	13	62,266	8,444	54,927	56,690
Nonaccrual Loans with no Allowance for Credit Loss	0		2,782
SVB Private Bank
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	6,517	4,857	5,480	5,644	3,809	3,919
Nonaccrual Loans with no Allowance for Credit Loss	6,517		3,714
Balance sheet dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	11,842	0	0	4,974	4,736	5,004
Nonaccrual Loans with no Allowance for Credit Loss	0		0
Premium wine
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	1,681	700	204	244	268	285
Nonaccrual Loans with no Allowance for Credit Loss	997		0
Other
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	61	0	0	0	0	792
Nonaccrual Loans with no Allowance for Credit Loss	61		0
SBA loans
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	4,202	0	0
Nonaccrual Loans with no Allowance for Credit Loss	0		0
Early stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	24,422	18,414	11,093	10,290	8,697	7,616
Nonaccrual Loans with no Allowance for Credit Loss	0		460
Mid stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	8,119	12,180	17,330	28,699	32,099	4,751
Nonaccrual Loans with no Allowance for Credit Loss	368		274
Later stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	10,498	14,443	6,296	38,346	23,140	11,385
Nonaccrual Loans with no Allowance for Credit Loss	4		0
Sponsor led buyout | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	21,658	0	44,585	8,365	38,237	39,534
Nonaccrual Loans with no Allowance for Credit Loss	0		0
Other | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans	5,317	$ 13	17,681	$ 79	$ 16,690	$ 17,156
Nonaccrual Loans with no Allowance for Credit Loss	$ 0		$ 2,782