Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Composition of Loans, Net of Unearned Income (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	$ 45,181,488	$ 33,164,636
Allowance for credit loss	(447,765)	(304,924)	$ (280,903)	$ (255,024)
Net loans	44,733,723	32,859,712
Global fund banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	25,543,198	17,696,794
Allowance for credit loss	(45,584)	(107,285)	(93,781)	(82,468)
Investor dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	4,971,818	4,335,195
Allowance for credit loss	(213,357)	(82,370)	(72,101)	(61,022)
Investor dependent | Early stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,485,866	1,624,221
Allowance for credit loss	(86,674)	(26,245)	(25,885)	(22,742)
Investor dependent | Mid stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,564,870	1,047,398
Investor dependent | Later stage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,921,082	1,663,576
Cash flow dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	4,934,533	4,424,238
Cash flow dependent | Sponsor led buyout
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,989,173	2,185,497
Cash flow dependent | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	2,945,360	2,238,741
Private Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	4,901,056	3,492,269
Allowance for credit loss	(53,629)	(21,551)	$ (20,583)	$ (16,441)
Balance sheet dependent
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	2,191,023	1,286,153
Premium wine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,052,643	1,062,264
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	27,687	867,723
SBA loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, amortized cost	1,559,530	0
Allowance for credit loss	$ (1,910)	$ 0