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	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 7,146,926
2019	4,598,266
2018	2,159,063
2017	1,095,436
2016	585,426
2015	670,298
Revolving Loans	22,098,467
Revolving Loans Converted to Term Loans	60,009
Total	38,413,891	$ 33,164,636
Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	105,711
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	36,874,725
Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,433,455
Global fund banking
Financing Receivable, Credit Quality Indicator [Line Items]
2020	271,172
2019	156,722
2018	70,084
2017	36,907
2016	2,552
2015	11,588
Revolving Loans	19,023,933
Revolving Loans Converted to Term Loans	11,560
Total	19,584,518	17,696,794
Global fund banking \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	8
2018	0
2017	0
2016	0
2015	0
Revolving Loans	5
Revolving Loans Converted to Term Loans	0
Total	13
Global fund banking \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	271,164
2019	156,714
2018	70,084
2017	36,907
2016	2,552
2015	11,588
Revolving Loans	19,022,934
Revolving Loans Converted to Term Loans	4,780
Total	19,576,723
Global fund banking \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	8
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	994
Revolving Loans Converted to Term Loans	6,780
Total	7,782
Investor dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,223,466
2019	1,467,917
2018	653,172
2017	167,774
2016	14,998
2015	21,300
Revolving Loans	553,994
Revolving Loans Converted to Term Loans	9,048
Total	5,111,669	4,335,195
Investor dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	69,934
Investor dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,541,543
Investor dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	500,192
Investor dependent \| Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	612,434
2019	529,801
2018	184,245
2017	49,252
2016	4,960
2015	757
Revolving Loans	87,922
Revolving Loans Converted to Term Loans	1,570
Total	1,470,941	1,624,221
Investor dependent \| Early stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,466
2019	8,870
2018	6,956
2017	463
2016	0
2015	4
Revolving Loans	973
Revolving Loans Converted to Term Loans	0
Total	19,732
Investor dependent \| Early stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	589,224
2019	452,550
2018	140,448
2017	37,911
2016	2,430
2015	390
Revolving Loans	73,199
Revolving Loans Converted to Term Loans	637
Total	1,296,789
Investor dependent \| Early stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	20,744
2019	68,381
2018	36,841
2017	10,878
2016	2,530
2015	363
Revolving Loans	13,750
Revolving Loans Converted to Term Loans	933
Total	154,420
Investor dependent \| Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	786,333
2019	390,402
2018	247,445
2017	55,847
2016	9,476
2015	2,725
Revolving Loans	132,072
Revolving Loans Converted to Term Loans	2,494
Total	1,626,794	1,047,398
Investor dependent \| Mid stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2
2019	2,558
2018	5,405
2017	3,519
2016	0
2015	0
Revolving Loans	143
Revolving Loans Converted to Term Loans	0
Total	11,627
Investor dependent \| Mid stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	726,708
2019	344,458
2018	209,372
2017	39,603
2016	7,510
2015	2,725
Revolving Loans	116,655
Revolving Loans Converted to Term Loans	2,494
Total	1,449,525
Investor dependent \| Mid stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	59,623
2019	43,386
2018	32,668
2017	12,725
2016	1,966
2015	0
Revolving Loans	15,274
Revolving Loans Converted to Term Loans	0
Total	165,642
Investor dependent \| Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	824,699
2019	547,714
2018	221,482
2017	62,675
2016	562
2015	17,818
Revolving Loans	334,000
Revolving Loans Converted to Term Loans	4,984
Total	2,013,934	1,663,576
Investor dependent \| Later stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	17,506
2019	1,886
2018	12,434
2017	0
2016	0
2015	0
Revolving Loans	6,749
Revolving Loans Converted to Term Loans	0
Total	38,575
Investor dependent \| Later stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	790,085
2019	473,800
2018	178,768
2017	60,009
2016	562
2015	9,110
Revolving Loans	277,911
Revolving Loans Converted to Term Loans	4,984
Total	1,795,229
Investor dependent \| Later stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	17,108
2019	72,028
2018	30,280
2017	2,666
2016	0
2015	8,708
Revolving Loans	49,340
Revolving Loans Converted to Term Loans	0
Total	180,130
Cash flow dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,052,665
2019	1,313,244
2018	647,477
2017	372,800
2016	102,548
2015	346
Revolving Loans	1,173,320
Revolving Loans Converted to Term Loans	0
Total	4,662,400	4,424,238
Cash flow dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	27,877
Cash flow dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,142,396
Cash flow dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	492,127
Cash flow dependent \| Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
2020	577,833
2019	683,895
2018	379,215
2017	254,926
2016	62,505
2015	0
Revolving Loans	103,869
Revolving Loans Converted to Term Loans	0
Total	2,062,243	2,185,497
Cash flow dependent \| Sponsor led buyout \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	33
2019	11,907
2018	0
2017	7,200
2016	0
2015	0
Revolving Loans	2,452
Revolving Loans Converted to Term Loans	0
Total	21,592
Cash flow dependent \| Sponsor led buyout \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	534,579
2019	601,938
2018	326,172
2017	226,326
2016	50,267
2015	0
Revolving Loans	88,661
Revolving Loans Converted to Term Loans	0
Total	1,827,943
Cash flow dependent \| Sponsor led buyout \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	43,221
2019	70,050
2018	53,043
2017	21,400
2016	12,238
2015	0
Revolving Loans	12,756
Revolving Loans Converted to Term Loans	0
Total	212,708
Cash flow dependent \| Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	474,832
2019	629,349
2018	268,262
2017	117,874
2016	40,043
2015	346
Revolving Loans	1,069,451
Revolving Loans Converted to Term Loans	0
Total	2,600,157	2,238,741
Cash flow dependent \| Other \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	3,845
2017	0
2016	0
2015	0
Revolving Loans	2,440
Revolving Loans Converted to Term Loans	0
Total	6,285
Cash flow dependent \| Other \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	465,243
2019	574,231
2018	189,501
2017	116,918
2016	39,627
2015	346
Revolving Loans	928,587
Revolving Loans Converted to Term Loans	0
Total	2,314,453
Cash flow dependent \| Other \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9,589
2019	55,118
2018	74,916
2017	956
2016	416
2015	0
Revolving Loans	138,424
Revolving Loans Converted to Term Loans	0
Total	279,419
SVB Private Bank
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,192,480
2019	1,218,069
2018	425,955
2017	399,048
2016	347,695
2015	471,702
Revolving Loans	369,629
Revolving Loans Converted to Term Loans	321
Total	4,424,899	3,492,269
SVB Private Bank \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	520
2018	2,475
2017	0
2016	0
2015	1,702
Revolving Loans	735
Revolving Loans Converted to Term Loans	0
Total	5,432
SVB Private Bank \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,191,024
2019	1,212,000
2018	420,440
2017	397,847
2016	342,594
2015	463,198
Revolving Loans	368,107
Revolving Loans Converted to Term Loans	321
Total	4,395,531
SVB Private Bank \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,456
2019	5,549
2018	3,040
2017	1,201
2016	5,101
2015	6,802
Revolving Loans	787
Revolving Loans Converted to Term Loans	0
Total	23,936
Balance sheet dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	435,006
2019	211,062
2018	243,088
2017	32,448
2016	0
2015	675
Revolving Loans	774,435
Revolving Loans Converted to Term Loans	1,506
Total	1,698,220	1,286,153
Balance sheet dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	675
Revolving Loans	1
Revolving Loans Converted to Term Loans	0
Total	676
Balance sheet dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	374,768
2019	202,185
2018	237,529
2017	31,838
2016	0
2015	0
Revolving Loans	717,771
Revolving Loans Converted to Term Loans	1,506
Total	1,565,597
Balance sheet dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	60,238
2019	8,877
2018	5,559
2017	610
2016	0
2015	0
Revolving Loans	56,663
Revolving Loans Converted to Term Loans	0
Total	131,947
Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
2020	168,625
2019	207,862
2018	106,195
2017	84,559
2016	117,633
2015	164,607
Revolving Loans	194,908
Revolving Loans Converted to Term Loans	37,574
Total	1,081,963	1,062,264
Premium wine \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	1,662
2015	0
Revolving Loans	13
Revolving Loans Converted to Term Loans	0
Total	1,675
Premium wine \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	154,624
2019	181,416
2018	70,297
2017	84,221
2016	102,297
2015	156,397
Revolving Loans	154,685
Revolving Loans Converted to Term Loans	37,574
Total	941,511
Premium wine \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	14,001
2019	26,446
2018	35,898
2017	338
2016	13,674
2015	8,210
Revolving Loans	40,210
Revolving Loans Converted to Term Loans	0
Total	138,777
Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,496
2019	23,390
2018	13,092
2017	1,900
2016	0
2015	80
Revolving Loans	8,248
Revolving Loans Converted to Term Loans	0
Total	48,206	867,723
Other \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	104
2018	0
2017	0
2016	0
2015	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	104
Other \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,474
2019	23,286
2018	13,092
2017	1,900
2016	0
2015	80
Revolving Loans	8,209
Revolving Loans Converted to Term Loans	0
Total	48,041
Other \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	22
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	39
Revolving Loans Converted to Term Loans	0
Total	61
SBA loans

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