Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Nonaccrual Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	$ 50,607	$ 133,623	$ 102,669	$ 94,142
Additions	66,116	39,460	102,462	90,317
Paydowns and Other Reductions	(17,784)	(57,507)	(80,461)	(63,988)
Charge-offs	(4,613)	(18,935)	(30,344)	(23,830)
Ending Balance	94,326	96,641	94,326	96,641
Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	45,037	63,936	34,719	23,752
Additions	11,059	37,278	46,717	85,873
Paydowns and Other Reductions	(8,444)	(9,401)	(11,468)	(13,442)
Charge-offs	(4,613)	(14,478)	(26,929)	(18,848)
Ending Balance	43,039	77,335	43,039	77,335
Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	13	54,927	62,266	56,690
Additions	30,238	79	30,238	79
Paydowns and Other Reductions	(3,276)	(44,160)	(62,887)	(45,457)
Charge-offs	0	(2,402)	(2,642)	(2,868)
Ending Balance	26,975	8,444	26,975	8,444
SVB Private Bank
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	4,857	3,809	5,480	3,919
Additions	2,634	1,865	2,634	1,880
Paydowns and Other Reductions	(974)	(22)	(1,016)	(88)
Charge-offs	0	(8)	(581)	(67)
Ending Balance	6,517	5,644	6,517	5,644
Balance sheet dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	0	4,736	0	5,004
Additions	16,742	238	16,742	238
Paydowns and Other Reductions	(4,900)	0	(4,900)	(268)
Charge-offs	0	0	0	0
Ending Balance	11,842	4,974	11,842	4,974
Premium wine
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	700	268	204	285
Additions	998	0	1,686	0
Paydowns and Other Reductions	(17)	(24)	(17)	(41)
Charge-offs	0	0	(192)	0
Ending Balance	1,681	244	1,681	244
Other
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	0	0	0	792
Additions	234	0	234	0
Paydowns and Other Reductions	(173)	0	(173)	(792)
Charge-offs	0	0	0	0
Ending Balance	61	0	61	0
Private equity/venture capital
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	0	5,947	0	3,700
Additions	9	0	9	2,247
Paydowns and Other Reductions	0	(3,900)	0	(3,900)
Charge-offs	0	(2,047)	0	(2,047)
Ending Balance	9	0	9	0
SBA loans
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	0		0
Additions	4,202		4,202
Paydowns and Other Reductions	0		0
Charge-offs	0		0
Ending Balance	4,202		4,202
Mid stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	12,180	32,099	17,330	4,751
Additions	494	10,392	12,585	42,491
Paydowns and Other Reductions	(399)	(869)	(787)	(1,390)
Charge-offs	(4,156)	(12,923)	(21,009)	(17,153)
Ending Balance	8,119	28,699	8,119	28,699
Later stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	14,443	23,140	6,296	11,385
Additions	959	18,507	12,183	30,570
Paydowns and Other Reductions	(4,904)	(3,301)	(4,776)	(3,609)
Charge-offs	0	0	(3,205)	0
Ending Balance	10,498	38,346	10,498	38,346
Sponsor led buyout | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	0	38,237	44,585	39,534
Additions	21,658	0	21,658	0
Paydowns and Other Reductions	0	(27,470)	(41,961)	(28,767)
Charge-offs	0	(2,402)	(2,624)	(2,402)
Ending Balance	21,658	8,365	21,658	8,365
Other | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	13	16,690	17,681	17,156
Additions	8,580	79	8,580	79
Paydowns and Other Reductions	(3,276)	(16,690)	(20,926)	(16,690)
Charge-offs	0	0	(18)	(466)
Ending Balance	5,317	79	5,317	79
Early stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	18,414	8,697	11,093	7,616
Additions	9,606	8,379	21,949	12,812
Paydowns and Other Reductions	(3,141)	(5,231)	(5,905)	(8,443)
Charge-offs	(457)	(1,555)	(2,715)	(1,695)
Ending Balance	$ 24,422	$ 10,290	$ 24,422	$ 10,290