Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Composition of Loans, Net of Unearned Income (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	$ 35,968,085	$ 33,164,636
Allowance for credit losses	(548,963)	(304,924)	$ (300,151)	$ (280,903)
Net loans	35,419,122	32,859,712
Private equity/venture capital
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	18,868,875	17,696,794
Allowance for credit losses	(56,774)	(107,285)	(95,311)	(93,781)
Investor dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	5,236,710	4,335,195
Allowance for credit losses	(275,701)	(82,370)	(95,056)	(72,101)
Investor dependent | Early stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,806,011	1,624,221
Allowance for credit losses	(127,189)	(26,245)	(26,730)	(25,885)
Investor dependent | Mid stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,399,209	1,047,398
Allowance for credit losses	(51,962)	(15,936)	(38,163)	(20,999)
Investor dependent | Later stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	2,031,490	1,663,576
Allowance for credit losses	(96,550)	(40,189)	(30,163)	(25,217)
Cash flow dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	4,877,302	4,424,238
Allowance for credit losses	(81,507)	(68,098)	(61,447)	(66,028)
Cash flow dependent | Sponsor led buyout
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	2,121,007	2,185,497
Allowance for credit losses	(42,091)	(42,939)	(40,933)	(44,274)
Cash flow dependent | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	2,756,295	2,238,741
Allowance for credit losses	(39,416)	(25,159)	(20,514)	(21,754)
SVB Private Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	3,669,295	3,492,269
Allowance for credit losses	(87,795)	(21,551)	(19,964)	(20,583)
Balance sheet dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,850,941	1,286,153
Allowance for credit losses	(23,235)	(12,722)	(21,632)	(21,707)
Premium wine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,056,927	1,062,264
Allowance for credit losses	(12,377)	(5,296)	(3,949)	(3,646)
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	408,035	867,723
Allowance for credit losses	$ (11,574)	$ (7,602)	$ (2,792)	$ (3,057)