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	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	$ 548,963	$ 300,151	$ 304,924	$ 280,903
Charge-offs	(15,055)	(26,435)	(51,951)	(35,435)
Recoveries	4,073	9,820	11,828	11,245
Provision for (Reduction of) Credit Losses	51,899	19,148	300,800	44,969
Foreign Currency Translation Adjustments	(52)	(796)	(1,237)	206
Allowance for credit loss, ending balance	589,828	301,888	589,828	301,888
Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			25,464
Private equity/venture capital
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	56,774	95,311	107,285	93,781
Charge-offs	0	(2,047)	0	(2,047)
Recoveries	0	0	0	0
Provision for (Reduction of) Credit Losses	(3,051)	8,336	16,506	9,819
Foreign Currency Translation Adjustments	0	(347)	(180)	(300)
Allowance for credit loss, ending balance	53,723	101,253	53,723	101,253
Private equity/venture capital | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			(69,888)
Investor dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	275,701	95,056	82,370	72,101
Charge-offs	(5,417)	(21,022)	(38,916)	(29,206)
Recoveries	3,659	5,390	8,569	6,605
Provision for (Reduction of) Credit Losses	18,362	18,518	169,759	47,532
Foreign Currency Translation Adjustments	(38)	(769)	(1,139)	141
Allowance for credit loss, ending balance	292,267	97,173	292,267	97,173
Investor dependent | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			71,624
Investor dependent | Early stage
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	127,189	26,730	26,245	25,885
Charge-offs	(1,764)	(7,627)	(11,947)	(9,295)
Recoveries	2,390	3,357	3,963	3,925
Provision for (Reduction of) Credit Losses	20,451	8,878	90,665	10,764
Foreign Currency Translation Adjustments	4	(369)	(567)	(310)
Allowance for credit loss, ending balance	148,270	30,969	148,270	30,969
Investor dependent | Early stage | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			39,911
Investor dependent | Mid stage
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	51,962	38,163	15,936	20,999
Charge-offs	(3,653)	(13,395)	(12,985)	(19,911)
Recoveries	1,269	900	4,606	903
Provision for (Reduction of) Credit Losses	6,861	2,708	42,006	25,665
Foreign Currency Translation Adjustments	(46)	(112)	(133)	608
Allowance for credit loss, ending balance	56,393	28,264	56,393	28,264
Investor dependent | Mid stage | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			6,963
Investor dependent | Later stage
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	96,550	30,163	40,189	25,217
Charge-offs	0	0	(13,984)	0
Recoveries	0	1,133	0	1,777
Provision for (Reduction of) Credit Losses	(8,950)	6,932	37,088	11,103
Foreign Currency Translation Adjustments	4	(288)	(439)	(157)
Allowance for credit loss, ending balance	87,604	37,940	87,604	37,940
Investor dependent | Later stage | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			24,750
Cash flow dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	81,507	61,447	68,098	66,028
Charge-offs	(3,385)	(2,402)	(6,009)	(3,118)
Recoveries	1	4,397	2,846	4,397
Provision for (Reduction of) Credit Losses	19,831	(7,053)	33,181	(10,800)
Foreign Currency Translation Adjustments	(1)	293	(258)	175
Allowance for credit loss, ending balance	97,953	56,682	97,953	56,682
Cash flow dependent | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			95
Cash flow dependent | Sponsor led buyout
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	42,091	40,933	42,939	44,274
Charge-offs	0	(2,402)	(2,624)	(2,402)
Recoveries	0	0	2,845	0
Provision for (Reduction of) Credit Losses	12,763	(6,677)	8,675	(9,916)
Foreign Currency Translation Adjustments	(1)	277	(133)	175
Allowance for credit loss, ending balance	54,853	32,131	54,853	32,131
Cash flow dependent | Sponsor led buyout | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			3,151
Cash flow dependent | Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	39,416	20,514	25,159	21,754
Charge-offs	(3,385)	0	(3,385)	(716)
Recoveries	1	4,397	1	4,397
Provision for (Reduction of) Credit Losses	7,068	(376)	24,506	(884)
Foreign Currency Translation Adjustments	0	16	(125)	0
Allowance for credit loss, ending balance	43,100	24,551	43,100	24,551
Cash flow dependent | Other | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			(3,056)
SVB Private Bank
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	87,795	19,964	21,551	20,583
Charge-offs	(1,035)	(960)	(1,616)	(1,019)
Recoveries	0	15	0	225
Provision for (Reduction of) Credit Losses	4,585	1,438	59,075	692
Foreign Currency Translation Adjustments	0	(60)	(280)	(84)
Allowance for credit loss, ending balance	91,345	20,397	91,345	20,397
SVB Private Bank | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			12,615
Balance sheet dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	23,235	21,632	12,722	21,707
Charge-offs	(4,900)	0	(4,900)	0
Recoveries	0	0	0	0
Provision for (Reduction of) Credit Losses	6,393	(4,566)	18,344	(4,639)
Foreign Currency Translation Adjustments	0	190	(74)	188
Allowance for credit loss, ending balance	24,728	17,256	24,728	17,256
Balance sheet dependent | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			(1,364)
Premium wine
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	12,377	3,949	5,296	3,646
Charge-offs	0	0	(192)	0
Recoveries	0	0	0	0
Provision for (Reduction of) Credit Losses	(58)	290	3,605	584
Foreign Currency Translation Adjustments	0	(12)	(40)	(3)
Allowance for credit loss, ending balance	12,319	4,227	12,319	4,227
Premium wine | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			3,650
Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	11,574	2,792	7,602	3,057
Charge-offs	(318)	(4)	(318)	(45)
Recoveries	413	18	413	18
Provision for (Reduction of) Credit Losses	1,979	2,185	(3,528)	1,781
Foreign Currency Translation Adjustments	(13)	(91)	734	89
Allowance for credit loss, ending balance	13,635	$ 4,900	13,635	$ 4,900
Other | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			8,732
SBA loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	0		0
Charge-offs	0		0
Recoveries	0		0
Provision for (Reduction of) Credit Losses	3,858		3,858
Foreign Currency Translation Adjustments	0		0
Allowance for credit loss, ending balance	$ 3,858		3,858
SBA loans | Cumulative adjustment for the adoption of amendment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance			$ 0