Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Credit Quality Indicators, Broken out by Risk-Based Segments and Vintage Year (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 2,889,750	$ 9,153,860
2020	8,169,000	4,008,276
2019	3,413,150	1,861,154
2018	1,703,081	934,386
2017	807,970	530,328
Prior	1,006,985	598,525
Revolving Loans	29,649,783	28,040,704
Revolving Loans Converted to Term Loans	50,938	54,255
Unallocated	(15,491)
Loans, amortized cost	47,675,166	45,181,488
Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	90,247
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	46,348,701
Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	1,236,218
Global fund banking
Financing Receivable, Credit Quality Indicator [Line Items]
2021	267,501	439,497
2020	263,243	48,305
2019	44,640	68,491
2018	59,520	22,878
2017	21,416	2,389
Prior	7,773	5,999
Revolving Loans	26,638,069	24,947,838
Revolving Loans Converted to Term Loans	4,764	7,801
Unallocated	0
Loans, amortized cost	27,306,926	25,543,198
Global fund banking \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	3
2020	0	8
2019	8	0
2018	0	0
2017	0	0
Prior	0	0
Revolving Loans	10	0
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	18	11
Global fund banking \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	267,498	439,494
2020	263,243	48,297
2019	44,632	68,491
2018	59,520	22,878
2017	21,416	2,389
Prior	7,773	5,999
Revolving Loans	26,627,712	24,947,428
Revolving Loans Converted to Term Loans	697	2,378
Unallocated	0
Loans, amortized cost	27,292,491	25,537,354
Global fund banking \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	3	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving Loans	10,347	410
Revolving Loans Converted to Term Loans	4,067	5,423
Unallocated	0
Loans, amortized cost	14,417	5,833
Investor dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2021	724,210	2,544,507
2020	2,413,278	1,253,486
2019	1,007,898	528,189
2018	440,372	115,532
2017	59,958	9,888
Prior	17,151	17,072
Revolving Loans	496,161	495,047
Revolving Loans Converted to Term Loans	8,041	8,097
Unallocated	0
Loans, amortized cost	5,167,069	4,971,818
Investor dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	35,169
Investor dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	4,717,953
Investor dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	413,947
Investor dependent \| Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
2021	203,198	716,333
2020	667,047	452,038
2019	368,452	152,458
2018	122,515	42,808
2017	22,288	4,791
Prior	2,914	739
Revolving Loans	136,234	116,082
Revolving Loans Converted to Term Loans	560	617
Unallocated	0
Loans, amortized cost	1,523,208	1,485,866
Investor dependent \| Early stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	211	2,438
2020	454	9,354
2019	3,037	5,368
2018	3,124	441
2017		0
Prior	0	0
Revolving Loans	940	739
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	7,766	18,340
Investor dependent \| Early stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	197,867	667,006
2020	584,281	370,189
2019	296,776	120,920
2018	95,495	32,163
2017	16,114	1,234
Prior	1,122	405
Revolving Loans	111,366	96,363
Revolving Loans Converted to Term Loans	560	617
Unallocated	0
Loans, amortized cost	1,303,581	1,288,897
Investor dependent \| Early stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	5,120	46,889
2020	82,312	72,495
2019	68,639	26,170
2018	23,896	10,204
2017	6,174	3,557
Prior	1,792	334
Revolving Loans	23,928	18,980
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	211,861	178,629
Investor dependent \| Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
2021	258,309	883,729
2020	752,054	350,813
2019	271,501	171,829
2018	140,071	33,615
2017	23,654	5,086
Prior	7,752	6,699
Revolving Loans	132,349	110,604
Revolving Loans Converted to Term Loans	2,495	2,495
Unallocated	0
Loans, amortized cost	1,588,185	1,564,870
Investor dependent \| Mid stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	10
2020	0	614
2019	0	218
2018	0	2,539
2017	0	0
Prior	0	675
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	0	4,056
Investor dependent \| Mid stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	253,799	840,431
2020	708,740	301,905
2019	253,486	145,588
2018	129,298	22,834
2017	19,909	5,086
Prior	2,754	1,026
Revolving Loans	121,676	101,423
Revolving Loans Converted to Term Loans	2,495	2,495
Unallocated	0
Loans, amortized cost	1,492,157	1,420,788
Investor dependent \| Mid stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	4,510	43,288
2020	43,314	48,294
2019	18,015	26,023
2018	10,773	8,242
2017	3,745	0
Prior	4,998	4,998
Revolving Loans	10,673	9,181
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	96,028	140,026
Investor dependent \| Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
2021	262,703	944,445
2020	994,177	450,635
2019	367,945	203,902
2018	177,786	39,109
2017	14,016	11
Prior	6,485	9,634
Revolving Loans	227,578	268,361
Revolving Loans Converted to Term Loans	4,986	4,985
Unallocated	0
Loans, amortized cost	2,055,676	1,921,082
Investor dependent \| Later stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	16,691
2020	15,997	1,797
2019	1,676	3,522
2018	3,280	0
2017	0	0
Prior	0	0
Revolving Loans	6,450	6,647
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	27,403	28,657
Investor dependent \| Later stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	262,703	905,468
2020	942,741	393,584
2019	338,516	170,128
2018	165,935	37,967
2017	14,016	11
Prior	5,593	8,087
Revolving Loans	187,725	224,432
Revolving Loans Converted to Term Loans	4,986	4,985
Unallocated	0
Loans, amortized cost	1,922,215	1,744,662
Investor dependent \| Later stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	22,286
2020	35,439	55,254
2019	27,753	30,252
2018	8,571	1,142
2017	0	0
Prior	892	1,547
Revolving Loans	33,403	37,282
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	106,058	147,763
Cash flow dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2021	764,788	1,690,801
2020	1,451,828	1,114,850
2019	853,685	546,307
2018	527,813	333,316
2017	280,299	88,711
Prior	51,344	101
Revolving Loans	1,014,419	1,160,447
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	4,944,176	4,934,533
Cash flow dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	45,476
Cash flow dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	4,524,529
Cash flow dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, amortized cost	374,171
Cash flow dependent \| Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
2021	310,562	792,013
2020	644,015	533,754
2019	449,334	328,807
2018	297,329	195,604
2017	165,291	49,903
Prior	49,398	0
Revolving Loans	68,638	89,092
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	1,984,567	1,989,173
Cash flow dependent \| Sponsor led buyout \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	33
2020	32	11,869
2019	11,838	16,068
2018	15,998	7,177
2017	7,158	0
Prior	0	0
Revolving Loans	4,822	4,849
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	39,848	39,996
Cash flow dependent \| Sponsor led buyout \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	310,562	791,480
2020	643,432	451,561
2019	406,962	273,719
2018	242,303	166,820
2017	147,618	36,900
Prior	36,269	0
Revolving Loans	57,269	75,492
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	1,844,415	1,795,972
Cash flow dependent \| Sponsor led buyout \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	500
2020	551	70,324
2019	30,534	39,020
2018	39,028	21,607
2017	10,515	13,003
Prior	13,129	0
Revolving Loans	6,547	8,751
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	100,304	153,205
Cash flow dependent \| Other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	454,226	898,788
2020	807,813	581,096
2019	404,351	217,500
2018	230,484	137,712
2017	115,008	38,808
Prior	1,946	101
Revolving Loans	945,781	1,071,355
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	2,959,609	2,945,360
Cash flow dependent \| Other \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	4,552
2018	4,418	0
2017	0	0
Prior	0	0
Revolving Loans	1,210	1,452
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	5,628	6,004
Cash flow dependent \| Other \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	454,225	879,542
2020	791,748	513,242
2019	343,877	179,169
2018	158,992	133,235
2017	111,051	38,808
Prior	1,946	101
Revolving Loans	818,275	933,274
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	2,680,114	2,677,371
Cash flow dependent \| Other \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1	19,246
2020	16,065	67,854
2019	60,474	33,779
2018	67,074	4,477
2017	3,957	0
Prior	0	0
Revolving Loans	126,296	136,629
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	273,867	261,985
SVB Private Bank
Financing Receivable, Credit Quality Indicator [Line Items]
2021	412,282	1,881,664
2020	1,824,944	1,163,451
2019	1,073,284	402,034
2018	373,838	354,059
2017	322,813	299,971
Prior	657,120	415,313
Revolving Loans	398,915	383,904
Revolving Loans Converted to Term Loans	631	660
Unallocated	0
Loans, amortized cost	5,063,827	4,901,056
SVB Private Bank \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	563
2019	0	3,197
2018	6,079	0
2017	0	0
Prior	1,657	1,679
Revolving Loans	709	713
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	8,445	6,152
SVB Private Bank \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	412,282	1,878,184
2020	1,821,765	1,152,903
2019	1,064,886	394,351
2018	364,246	352,857
2017	319,602	294,870
Prior	646,021	405,909
Revolving Loans	395,302	382,442
Revolving Loans Converted to Term Loans	631	660
Unallocated	0
Loans, amortized cost	5,024,735	4,862,176
SVB Private Bank \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	3,480
2020	3,179	9,985
2019	8,398	4,486
2018	3,513	1,202
2017	3,211	5,101
Prior	9,442	7,725
Revolving Loans	2,904	749
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	30,647	32,728
Balance sheet dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2021	263,669	893,500
2020	891,433	193,873
2019	197,815	198,703
2018	181,241	19,213
2017	33,922	0
Prior	0	0
Revolving Loans	931,940	884,229
Revolving Loans Converted to Term Loans	1,504	1,505
Unallocated	0
Loans, amortized cost	2,501,524	2,191,023
Balance sheet dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving Loans	0	0
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	0	0
Balance sheet dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	263,600	837,613
2020	832,914	190,140
2019	155,424	198,532
2018	181,241	19,213
2017	33,922	0
Prior	0	0
Revolving Loans	904,547	857,642
Revolving Loans Converted to Term Loans	1,504	1,505
Unallocated	0
Loans, amortized cost	2,373,152	2,104,645
Balance sheet dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	69	55,887
2020	58,519	3,733
2019	42,391	171
2018	0	0
2017	0	0
Prior	0	0
Revolving Loans	27,393	26,587
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	128,372	86,378
Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
2021	22,027	144,358
2020	143,001	218,030
2019	216,649	106,520
2018	103,655	89,388
2017	88,084	129,369
Prior	273,596	159,607
Revolving Loans	157,213	169,179
Revolving Loans Converted to Term Loans	35,998	36,192
Unallocated	0
Loans, amortized cost	1,040,223	1,052,643
Premium wine \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	42	0
2019	0	0
2018	0	0
2017	0	998
Prior	998	0
Revolving Loans	99	0
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	1,139	998
Premium wine \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	20,393	126,476
2020	129,671	193,744
2019	193,793	70,783
2018	87,586	79,088
2017	77,877	114,812
Prior	225,080	153,841
Revolving Loans	133,185	135,461
Revolving Loans Converted to Term Loans	35,998	36,192
Unallocated	0
Loans, amortized cost	903,583	910,397
Premium wine \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,634	17,882
2020	13,288	24,286
2019	22,856	35,737
2018	16,069	10,300
2017	10,207	13,559
Prior	47,518	5,766
Revolving Loans	23,929	33,718
Revolving Loans Converted to Term Loans	0	0
Unallocated	0
Loans, amortized cost	135,501	141,248
Other
Financing Receivable, Credit Quality Indicator [Line Items]
2021	21	3
2020	10,792	16,281
2019	19,179	10,910
2018	16,642	0

Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Credit Quality Indicators, Broken out by Risk-Based Segments and Vintage Year (Details) - USD ($)
$ in Thousands