Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Nonaccrual Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	$ 102,669	$ 94,142
Additions	36,346	50,857
Paydowns and Other Reductions	(62,677)	(6,481)
Charge-offs	(25,731)	(4,895)
Ending Balance	50,607	133,623
Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	34,719	23,752
Additions	35,658	48,595
Paydowns and Other Reductions	(3,024)	(4,041)
Charge-offs	(22,316)	(4,370)
Ending Balance	45,037	63,936
Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	62,266	56,690
Additions	0	0
Paydowns and Other Reductions	(59,611)	(1,297)
Charge-offs	(2,642)	(466)
Ending Balance	13	54,927
SVB Private Bank
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	5,480	3,919
Additions	0	15
Paydowns and Other Reductions	(42)	(66)
Charge-offs	(581)	(59)
Ending Balance	4,857	3,809
Balance sheet dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	0	5,004
Additions	0	0
Paydowns and Other Reductions	0	(268)
Charge-offs	0	0
Ending Balance	0	4,736
Premium wine
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	204	285
Additions	688	0
Paydowns and Other Reductions	0	(17)
Charge-offs	(192)	0
Ending Balance	700	268
Other
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	0	792
Additions	0	0
Paydowns and Other Reductions	0	(792)
Charge-offs	0	0
Ending Balance	0	0
Private equity/venture capital
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	0	3,700
Additions	0	2,247
Paydowns and Other Reductions	0	0
Charge-offs	0	0
Ending Balance	0	5,947
Mid stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	17,330	4,751
Additions	12,091	32,099
Paydowns and Other Reductions	(388)	(521)
Charge-offs	(16,853)	(4,230)
Ending Balance	12,180	32,099
Later stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	6,296	11,385
Additions	11,224	12,063
Paydowns and Other Reductions	128	(308)
Charge-offs	(3,205)	0
Ending Balance	14,443	23,140
Sponsor led buyout | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	44,585	39,534
Additions	0	0
Paydowns and Other Reductions	(41,961)	(1,297)
Charge-offs	(2,624)	0
Ending Balance	0	38,237
Other | Cash flow dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	17,681	17,156
Additions	0	0
Paydowns and Other Reductions	(17,650)	0
Charge-offs	(18)	(466)
Ending Balance	13	16,690
Early stage | Investor dependent
Financing Receivable, Nonaccrual [Line Items]
Beginning Balance	11,093	7,616
Additions	12,343	4,433
Paydowns and Other Reductions	(2,764)	(3,212)
Charge-offs	(2,258)	(140)
Ending Balance	$ 18,414	$ 8,697