Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Nonaccrual Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	$ 94,326	$ 96,641	$ 102,669	$ 94,142
Additions	70,000	53,643	172,462	143,960
Paydowns and Other Reductions	(38,754)	(22,510)	(119,215)	(86,498)
Charge-offs	(19,861)	(23,729)	(50,205)	(47,559)
Ending Balance	105,711	104,045	105,711	104,045
Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	43,039	77,335	34,719	23,752
Additions	53,338	14,631	100,055	100,504
Paydowns and Other Reductions	(6,582)	(16,785)	(18,050)	(30,227)
Charge-offs	(19,861)	(23,729)	(46,790)	(42,577)
Ending Balance	69,934	51,452	69,934	51,452
Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	26,975	8,444	62,266	56,690
Additions	12,528	37,307	42,766	37,386
Paydowns and Other Reductions	(11,626)	(640)	(74,513)	(46,097)
Charge-offs	0	0	(2,642)	(2,868)
Ending Balance	27,877	45,111	27,877	45,111
SVB Private Bank
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	6,517	5,644	5,480	3,919
Additions	3,348	1,531	5,982	3,411
Paydowns and Other Reductions	(4,433)	(86)	(5,449)	(174)
Charge-offs	0	0	(581)	(67)
Ending Balance	5,432	7,089	5,432	7,089
Balance sheet dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	11,842	4,974	0	5,004
Additions	675	0	17,417	238
Paydowns and Other Reductions	(11,841)	(4,974)	(16,741)	(5,242)
Charge-offs	0	0	0	0
Ending Balance	676	0	676	0
Premium wine
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	1,681	244	204	285
Additions	0	174	1,686	174
Paydowns and Other Reductions	(6)	(25)	(23)	(66)
Charge-offs	0	0	(192)	0
Ending Balance	1,675	393	1,675	393
Other
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	61	0	0	792
Additions	105	0	339	0
Paydowns and Other Reductions	(62)	0	(235)	(792)
Charge-offs	0	0	0	0
Ending Balance	104	0	104	0
Global fund banking
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	9	0	0	3,700
Additions	6	0	15	2,247
Paydowns and Other Reductions	(2)	0	(2)	(3,900)
Charge-offs	0	0	0	(2,047)
Ending Balance	13	0	13	0
SBA loans
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	4,202		0
Additions	0		4,202
Paydowns and Other Reductions	(4,202)		(4,202)
Charge-offs	0		0
Ending Balance	0		0
Mid stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	8,119	28,699	17,330	4,751
Additions	10,290	6	22,875	42,497
Paydowns and Other Reductions	(292)	(8,151)	(1,079)	(9,541)
Charge-offs	(6,490)	(15,323)	(27,499)	(32,476)
Ending Balance	11,627	5,231	11,627	5,231
Later stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	10,498	38,346	6,296	11,385
Additions	36,779	2,216	48,962	32,786
Paydowns and Other Reductions	(3,500)	(6,462)	(8,276)	(10,071)
Charge-offs	(5,202)	(6,837)	(8,407)	(6,837)
Ending Balance	38,575	27,263	38,575	27,263
Sponsor led buyout | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	21,658	8,365	44,585	39,534
Additions	172	37,294	21,830	37,294
Paydowns and Other Reductions	(238)	(640)	(42,199)	(29,407)
Charge-offs	0	0	(2,624)	(2,402)
Ending Balance	21,592	45,019	21,592	45,019
Other | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	5,317	79	17,681	17,156
Additions	12,356	13	20,936	92
Paydowns and Other Reductions	(11,388)	0	(32,314)	(16,690)
Charge-offs	0	0	(18)	(466)
Ending Balance	6,285	92	6,285	92
Early stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	24,422	10,290	11,093	7,616
Additions	6,269	12,409	28,218	25,221
Paydowns and Other Reductions	(2,790)	(2,172)	(8,695)	(10,615)
Charge-offs	(8,169)	(1,569)	(10,884)	(3,264)
Ending Balance	$ 19,732	$ 18,958	$ 19,732	$ 18,958