Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Composition of Loans, Net of Unearned Income (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	$ 47,675,166	$ 45,181,488
Allowance for credit losses	(391,751)	(447,765)	$ (548,963)	$ (304,924)
Net loans	47,283,415	44,733,723
Global fund banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	27,306,926	25,543,198
Investor dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	5,167,069	4,971,818
Allowance for credit losses	(166,933)	(213,357)	(275,701)	(82,370)
Investor dependent | Early stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,523,208	1,485,866
Allowance for credit losses	(62,247)	(86,674)	(127,189)	(26,245)
Investor dependent | Mid stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,588,185	1,564,870
Investor dependent | Later stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	2,055,676	1,921,082
Cash flow dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	4,944,176	4,934,533
Cash flow dependent | Sponsor led buyout
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,984,567	1,989,173
Cash flow dependent | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	2,959,609	2,945,360
SVB Private Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	5,063,827	4,901,056
Allowance for credit losses	(45,064)	(53,629)	$ (87,795)	$ (21,551)
Balance sheet dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	2,501,524	2,191,023
Premium wine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,040,223	1,052,643
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	45,688	27,687
SBA loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,605,733	1,559,530
Allowance for credit losses	$ 0	$ (1,910)