Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Activity Relating to our Allowance for Credit Losses for Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	$ 304,924	$ 280,903	$ 255,024
Charge-offs	(102,904)	(92,603)	(67,917)
Recoveries	29,018	21,038	11,636
Provision for (Reduction of) Loans	189,226	94,183	84,292
Foreign Currency Translation Adjustments	2,037	1,403	(2,132)
Allowance for credit loss, ending balance	447,765	304,924	280,903
Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	25,464
Allowance for credit loss, ending balance		25,464
Global fund banking
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	107,285	93,781	82,468
Charge-offs	0	(2,047)	(112)
Recoveries	0	2,047	0
Provision for (Reduction of) Loans	8,367	13,534	11,698
Foreign Currency Translation Adjustments	(180)	(30)	(273)
Allowance for credit loss, ending balance	45,584	107,285	93,781
Global fund banking | Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	(69,888)
Allowance for credit loss, ending balance		(69,888)
Investor dependent
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	82,370	72,101	61,022
Charge-offs	(88,643)	(84,823)	(49,222)
Recoveries	24,863	14,033	9,027
Provision for (Reduction of) Loans	124,970	80,799	52,120
Foreign Currency Translation Adjustments	(1,827)	260	(846)
Allowance for credit loss, ending balance	213,357	82,370	72,101
Investor dependent | Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	71,624
Allowance for credit loss, ending balance		71,624
Investor dependent | Early stage
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	26,245	25,885	22,742
Charge-offs	(35,305)	(31,568)	(32,495)
Recoveries	10,821	9,088	6,154
Provision for (Reduction of) Loans	45,825	22,462	29,788
Foreign Currency Translation Adjustments	(823)	378	(304)
Allowance for credit loss, ending balance	86,674	26,245	25,885
Investor dependent | Early stage | Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	39,911
Allowance for credit loss, ending balance		39,911
Investor dependent | Growth Stage
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	56,125	46,216	38,280
Charge-offs	(53,338)	(53,255)	(16,727)
Recoveries	14,042	4,945	2,873
Provision for (Reduction of) Loans	79,145	58,337	22,332
Foreign Currency Translation Adjustments	(1,004)	(118)	(542)
Allowance for credit loss, ending balance	126,683	56,125	46,216
Investor dependent | Growth Stage | Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	31,713
Allowance for credit loss, ending balance		31,713
Cash flow and balance sheet dependent
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	80,820	87,735	87,620
Charge-offs	(11,187)	(3,118)	(16,223)
Recoveries	2,846	4,683	2,064
Provision for (Reduction of) Loans	53,369	(9,093)	15,304
Foreign Currency Translation Adjustments	(330)	613	(1,030)
Allowance for credit loss, ending balance	124,249	80,820	87,735
Cash flow and balance sheet dependent | Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	(1,269)
Allowance for credit loss, ending balance		(1,269)
Private Bank
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	21,551	20,583	16,441
Charge-offs	(1,616)	(1,031)	(289)
Recoveries	30	255	486
Provision for (Reduction of) Loans	21,329	1,865	3,986
Foreign Currency Translation Adjustments	(280)	(121)	(41)
Allowance for credit loss, ending balance	53,629	21,551	20,583
Private Bank | Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	12,615
Allowance for credit loss, ending balance		12,615
Premium wine and other
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	12,898	6,703	7,473
Charge-offs	(1,458)	(1,584)	(2,071)
Recoveries	1,279	20	59
Provision for (Reduction of) Loans	(20,719)	7,078	1,184
Foreign Currency Translation Adjustments	4,654	681	58
Allowance for credit loss, ending balance	9,036	12,898	$ 6,703
Premium wine and other | Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	12,382
Allowance for credit loss, ending balance		12,382
SBA loans
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	0
Charge-offs	0
Recoveries	0
Provision for (Reduction of) Loans	1,910
Foreign Currency Translation Adjustments	0
Allowance for credit loss, ending balance	1,910	0
SBA loans | Cumulative adjustment for adoption of amendment
Financing Receivable, Impaired [Line Items]
Allowance for credit loss, beginning balance	$ 0
Allowance for credit loss, ending balance		$ 0