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	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 5,565,887
2019	5,112,533
2018	2,380,189
2017	1,297,687
2016	668,018
2015	810,194
Revolving Loans	20,815,649
Revolving Loans Converted to Term Loans	77,065
Total	36,727,222	$ 33,164,636
Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	94,326
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	35,128,848
Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,504,048
Private equity/venture capital
Financing Receivable, Credit Quality Indicator [Line Items]
2020	339,452
2019	188,430
2018	71,803
2017	39,857
2016	3,577
2015	16,055
Revolving Loans	17,237,162
Revolving Loans Converted to Term Loans	4,781
Total	17,901,117	17,696,794
Private equity/venture capital \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	9
2018	0
2017	0
2016	0
2015	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	9
Private equity/venture capital \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	339,398
2019	188,421
2018	71,803
2017	39,857
2016	3,577
2015	16,055
Revolving Loans	17,228,948
Revolving Loans Converted to Term Loans	4,781
Total	17,892,840
Private equity/venture capital \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	54
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	8,214
Revolving Loans Converted to Term Loans	0
Total	8,268
Investor dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,705,117
2019	1,704,134
2018	770,306
2017	228,434
2016	24,442
2015	27,778
Revolving Loans	678,665
Revolving Loans Converted to Term Loans	0
Total	5,138,876	4,335,195
Investor dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	43,039
Investor dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,527,816
Investor dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	568,021
Investor dependent \| Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	616,805
2019	716,550
2018	277,509
2017	68,823
2016	13,056
2015	6,057
Revolving Loans	98,776
Revolving Loans Converted to Term Loans	0
Total	1,797,576	1,624,221
Investor dependent \| Early stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,085
2019	8,670
2018	7,542
2017	2,771
2016	2,197
2015	0
Revolving Loans	1,157
Revolving Loans Converted to Term Loans	0
Total	24,422
Investor dependent \| Early stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	576,597
2019	614,464
2018	216,902
2017	53,103
2016	4,304
2015	355
Revolving Loans	83,497
Revolving Loans Converted to Term Loans	0
Total	1,549,222
Investor dependent \| Early stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	38,123
2019	93,416
2018	53,065
2017	12,949
2016	6,555
2015	5,702
Revolving Loans	14,122
Revolving Loans Converted to Term Loans	0
Total	223,932
Investor dependent \| Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	560,419
2019	395,859
2018	248,312
2017	74,949
2016	4,847
2015	7,355
Revolving Loans	144,031
Revolving Loans Converted to Term Loans	0
Total	1,435,772	1,047,398
Investor dependent \| Mid stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	210
2018	5,646
2017	2,041
2016	0
2015	0
Revolving Loans	222
Revolving Loans Converted to Term Loans	0
Total	8,119
Investor dependent \| Mid stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	527,905
2019	342,149
2018	194,287
2017	59,075
2016	1,502
2015	4,448
Revolving Loans	130,076
Revolving Loans Converted to Term Loans	0
Total	1,259,442
Investor dependent \| Mid stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	32,514
2019	53,500
2018	48,379
2017	13,833
2016	3,345
2015	2,907
Revolving Loans	13,733
Revolving Loans Converted to Term Loans	0
Total	168,211
Investor dependent \| Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	527,893
2019	591,725
2018	244,485
2017	84,662
2016	6,539
2015	14,366
Revolving Loans	435,858
Revolving Loans Converted to Term Loans	0
Total	1,905,528	1,663,576
Investor dependent \| Later stage \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1,435
2018	2,374
2017	3,885
2016	0
2015	0
Revolving Loans	2,804
Revolving Loans Converted to Term Loans	0
Total	10,498
Investor dependent \| Later stage \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	495,546
2019	564,400
2018	188,404
2017	73,703
2016	6,539
2015	7,860
Revolving Loans	382,700
Revolving Loans Converted to Term Loans	0
Total	1,719,152
Investor dependent \| Later stage \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	32,347
2019	25,890
2018	53,707
2017	7,074
2016	0
2015	6,506
Revolving Loans	50,354
Revolving Loans Converted to Term Loans	0
Total	175,878
Cash flow dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	762,468
2019	1,430,066
2018	691,803
2017	419,320
2016	112,158
2015	347
Revolving Loans	1,429,084
Revolving Loans Converted to Term Loans	0
Total	4,845,246	4,424,238
Cash flow dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	26,975
Cash flow dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,260,629
Cash flow dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	557,642
Cash flow dependent \| Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
2020	408,280
2019	718,988
2018	408,801
2017	301,863
2016	69,972
2015	0
Revolving Loans	149,535
Revolving Loans Converted to Term Loans	0
Total	2,057,439	2,185,497
Cash flow dependent \| Sponsor led buyout \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	19
2019	11,937
2018	0
2017	7,218
2016	0
2015	0
Revolving Loans	2,484
Revolving Loans Converted to Term Loans	0
Total	21,658
Cash flow dependent \| Sponsor led buyout \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	374,547
2019	637,287
2018	357,322
2017	262,844
2016	58,014
2015	0
Revolving Loans	129,239
Revolving Loans Converted to Term Loans	0
Total	1,819,253
Cash flow dependent \| Sponsor led buyout \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	33,714
2019	69,764
2018	51,479
2017	31,801
2016	11,958
2015	0
Revolving Loans	17,812
Revolving Loans Converted to Term Loans	0
Total	216,528
Cash flow dependent \| Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	354,188
2019	711,078
2018	283,002
2017	117,457
2016	42,186
2015	347
Revolving Loans	1,279,549
Revolving Loans Converted to Term Loans	0
Total	2,787,807	2,238,741
Cash flow dependent \| Other \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	1,140
2017	0
2016	0
2015	0
Revolving Loans	4,177
Revolving Loans Converted to Term Loans	0
Total	5,317
Cash flow dependent \| Other \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	339,862
2019	639,167
2018	193,797
2017	114,650
2016	41,605
2015	347
Revolving Loans	1,111,948
Revolving Loans Converted to Term Loans	0
Total	2,441,376
Cash flow dependent \| Other \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	14,326
2019	71,911
2018	88,065
2017	2,807
2016	581
2015	0
Revolving Loans	163,424
Revolving Loans Converted to Term Loans	0
Total	341,114
SVB Private Bank
Financing Receivable, Credit Quality Indicator [Line Items]
2020	596,908
2019	1,068,638
2018	446,090
2017	443,865
2016	365,880
2015	542,229
Revolving Loans	280,590
Revolving Loans Converted to Term Loans	72,077
Total	3,816,277	3,492,269
SVB Private Bank \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	1,570
2016	0
2015	2,901
Revolving Loans	2,046
Revolving Loans Converted to Term Loans	0
Total	6,517
SVB Private Bank \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	596,908
2019	1,062,779
2018	443,164
2017	440,490
2016	363,380
2015	531,090
Revolving Loans	277,942
Revolving Loans Converted to Term Loans	72,077
Total	3,787,830
SVB Private Bank \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	5,859
2018	2,926
2017	1,805
2016	2,500
2015	8,238
Revolving Loans	602
Revolving Loans Converted to Term Loans	0
Total	21,930
Balance sheet dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	216,893
2019	230,108
2018	250,312
2017	34,512
2016	4,545
2015	0
Revolving Loans	956,701
Revolving Loans Converted to Term Loans	0
Total	1,693,071	1,286,153
Balance sheet dependent \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	14
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	11,828
Revolving Loans Converted to Term Loans	0
Total	11,842
Balance sheet dependent \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	216,879
2019	221,481
2018	247,818
2017	33,048
2016	4,545
2015	0
Revolving Loans	864,436
Revolving Loans Converted to Term Loans	0
Total	1,588,207
Balance sheet dependent \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	8,627
2018	2,494
2017	1,464
2016	0
2015	0
Revolving Loans	80,437
Revolving Loans Converted to Term Loans	0
Total	93,022
Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
2020	87,219
2019	250,194
2018	109,596
2017	92,947
2016	98,862
2015	190,573
Revolving Loans	210,065
Revolving Loans Converted to Term Loans	0
Total	1,039,456	1,062,264
Premium wine \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	1,668
2015	0
Revolving Loans	13
Revolving Loans Converted to Term Loans	0
Total	1,681
Premium wine \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	85,177
2019	237,520
2018	73,632
2017	92,594
2016	93,214
2015	177,246
Revolving Loans	167,166
Revolving Loans Converted to Term Loans	0
Total	926,549
Premium wine \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,042
2019	12,674
2018	35,964
2017	353
2016	3,980
2015	13,327
Revolving Loans	42,886
Revolving Loans Converted to Term Loans	0
Total	111,226
Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	21,885
2019	240,963
2018	40,279
2017	38,752
2016	58,554
2015	33,212
Revolving Loans	23,382
Revolving Loans Converted to Term Loans	207
Total	457,234	867,723
Other \| Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	61
2018	0
2017	0
2016	0
2015	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	61
Other \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	21,785
2019	240,902
2018	40,279
2017	38,752
2016	58,554
2015	33,212
Revolving Loans	23,256
Revolving Loans Converted to Term Loans	207
Total	456,947
Other \| Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	100
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	126
Revolving Loans Converted to Term Loans	0
Total	226
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