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, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 1,920,419
2019	5,611,123
2018	2,746,347
2017	1,486,386
2016	773,241
2015	949,395
Revolving Loans	22,417,770
Revolving Loans Converted to Term Loans	63,404
Total	35,968,085	$ 33,164,636
Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	50,607
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	34,782,203
Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,135,275
Private equity/venture capital
Financing Receivable, Credit Quality Indicator [Line Items]
2020	167,887
2019	249,214
2018	92,652
2017	41,912
2016	3,990
2015	18,241
Revolving Loans	18,294,979
Revolving Loans Converted to Term Loans	0
Total	18,868,875	17,696,794
Private equity/venture capital | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Private equity/venture capital | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	167,852
2019	249,214
2018	92,652
2017	41,912
2016	3,990
2015	18,241
Revolving Loans	18,294,903
Revolving Loans Converted to Term Loans	0
Total	18,868,764
Private equity/venture capital | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	35
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	76
Revolving Loans Converted to Term Loans	0
Total	111
Investor dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	911,357
2019	2,045,200
2018	977,302
2017	342,926
2016	40,236
2015	32,734
Revolving Loans	886,955
Revolving Loans Converted to Term Loans	0
Total	5,236,710	4,335,195
Investor dependent | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	45,037
Investor dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,598,851
Investor dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	592,822
Investor dependent | Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	357,292
2019	853,512
2018	326,365
2017	111,561
2016	18,156
2015	9,328
Revolving Loans	129,797
Revolving Loans Converted to Term Loans	0
Total	1,806,011	1,624,221
Investor dependent | Early stage | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	4,995
2018	8,875
2017	3,337
2016	0
2015	0
Revolving Loans	1,207
Revolving Loans Converted to Term Loans	0
Total	18,414
Investor dependent | Early stage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	348,538
2019	764,930
2018	260,849
2017	86,592
2016	12,760
2015	3,460
Revolving Loans	111,178
Revolving Loans Converted to Term Loans	0
Total	1,588,307
Investor dependent | Early stage | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	8,754
2019	83,587
2018	56,641
2017	21,632
2016	5,396
2015	5,868
Revolving Loans	17,412
Revolving Loans Converted to Term Loans	0
Total	199,290
Investor dependent | Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	313,655
2019	429,624
2018	317,742
2017	98,899
2016	22,004
2015	8,302
Revolving Loans	208,983
Revolving Loans Converted to Term Loans	0
Total	1,399,209	1,047,398
Investor dependent | Mid stage | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	5,586
2017	6,342
2016	0
2015	0
Revolving Loans	252
Revolving Loans Converted to Term Loans	0
Total	12,180
Investor dependent | Mid stage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	304,548
2019	375,482
2018	267,047
2017	77,566
2016	10,772
2015	3,278
Revolving Loans	185,788
Revolving Loans Converted to Term Loans	0
Total	1,224,481
Investor dependent | Mid stage | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9,107
2019	54,142
2018	45,109
2017	14,991
2016	11,232
2015	5,024
Revolving Loans	22,943
Revolving Loans Converted to Term Loans	0
Total	162,548
Investor dependent | Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	240,410
2019	762,064
2018	333,195
2017	132,466
2016	76
2015	15,104
Revolving Loans	548,175
Revolving Loans Converted to Term Loans	0
Total	2,031,490	1,663,576
Investor dependent | Later stage | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1,521
2018	5,820
2017	4,153
2016	0
2015	0
Revolving Loans	2,949
Revolving Loans Converted to Term Loans	0
Total	14,443
Investor dependent | Later stage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	220,075
2019	696,219
2018	259,592
2017	104,208
2016	76
2015	13,203
Revolving Loans	492,690
Revolving Loans Converted to Term Loans	0
Total	1,786,063
Investor dependent | Later stage | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	20,335
2019	64,324
2018	67,783
2017	24,105
2016	0
2015	1,901
Revolving Loans	52,536
Revolving Loans Converted to Term Loans	0
Total	230,984
Cash flow dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	436,684
2019	1,513,920
2018	797,549
2017	436,379
2016	123,652
2015	20,245
Revolving Loans	1,548,873
Revolving Loans Converted to Term Loans	0
Total	4,877,302	4,424,238
Cash flow dependent | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	13
Cash flow dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,542,223
Cash flow dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total	335,066
Cash flow dependent | Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
2020	204,305
2019	786,448
2018	521,779
2017	308,405
2016	80,391
2015	19,703
Revolving Loans	199,976
Revolving Loans Converted to Term Loans	0
Total	2,121,007	2,185,497
Cash flow dependent | Sponsor led buyout | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Cash flow dependent | Sponsor led buyout | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	204,305
2019	756,752
2018	436,654
2017	276,232
2016	68,412
2015	19,703
Revolving Loans	190,003
Revolving Loans Converted to Term Loans	0
Total	1,952,061
Cash flow dependent | Sponsor led buyout | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	29,696
2018	85,125
2017	32,173
2016	11,979
2015	0
Revolving Loans	9,973
Revolving Loans Converted to Term Loans	0
Total	168,946
Cash flow dependent | Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	232,379
2019	727,472
2018	275,770
2017	127,974
2016	43,261
2015	542
Revolving Loans	1,348,897
Revolving Loans Converted to Term Loans	0
Total	2,756,295	2,238,741
Cash flow dependent | Other | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	2
2017	0
2016	0
2015	0
Revolving Loans	11
Revolving Loans Converted to Term Loans	0
Total	13
Cash flow dependent | Other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	232,375
2019	710,823
2018	235,585
2017	122,748
2016	43,198
2015	542
Revolving Loans	1,244,891
Revolving Loans Converted to Term Loans	0
Total	2,590,162
Cash flow dependent | Other | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4
2019	16,649
2018	40,183
2017	5,226
2016	63
2015	0
Revolving Loans	103,995
Revolving Loans Converted to Term Loans	0
Total	166,120
SVB Private Bank
Financing Receivable, Credit Quality Indicator [Line Items]
2020	200,593
2019	1,113,866
2018	477,055
2017	476,676
2016	442,054
2015	616,843
Revolving Loans	278,804
Revolving Loans Converted to Term Loans	63,404
Total	3,669,295	3,492,269
SVB Private Bank | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	1,588
2016	0
2015	1,181
Revolving Loans	2,088
Revolving Loans Converted to Term Loans	0
Total	4,857
SVB Private Bank | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	200,593
2019	1,106,485
2018	477,055
2017	472,672
2016	439,552
2015	603,906
Revolving Loans	276,109
Revolving Loans Converted to Term Loans	63,404
Total	3,639,776
SVB Private Bank | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	7,381
2018	0
2017	2,416
2016	2,502
2015	11,756
Revolving Loans	607
Revolving Loans Converted to Term Loans	0
Total	24,662
Balance sheet dependent
Financing Receivable, Credit Quality Indicator [Line Items]
2020	136,803
2019	229,722
2018	231,938
2017	64,114
2016	13,280
2015	0
Revolving Loans	1,175,084
Revolving Loans Converted to Term Loans	0
Total	1,850,941	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	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Balance sheet dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	136,803
2019	215,264
2018	228,831
2017	48,144
2016	13,280
2015	0
Revolving Loans	1,082,951
Revolving Loans Converted to Term Loans	0
Total	1,725,273
Balance sheet dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	14,458
2018	3,107
2017	15,970
2016	0
2015	0
Revolving Loans	92,133
Revolving Loans Converted to Term Loans	0
Total	125,668
Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
2020	51,487
2019	247,229
2018	109,835
2017	93,416
2016	89,878
2015	232,086
Revolving Loans	232,996
Revolving Loans Converted to Term Loans	0
Total	1,056,927	1,062,264
Premium wine | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	687
2015	0
Revolving Loans	13
Revolving Loans Converted to Term Loans	0
Total	700
Premium wine | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	51,487
2019	238,792
2018	95,464
2017	93,055
2016	84,186
2015	226,031
Revolving Loans	210,358
Revolving Loans Converted to Term Loans	0
Total	999,373
Premium wine | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	8,437
2018	14,371
2017	361
2016	5,005
2015	6,055
Revolving Loans	22,625
Revolving Loans Converted to Term Loans	0
Total	56,854
Other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	15,608
2019	211,972
2018	60,016
2017	30,963
2016	60,151
2015	29,246
Revolving Loans	79
Revolving Loans Converted to Term Loans	0
Total	408,035	$ 867,723
Other | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	15,595
2019	211,972
2018	60,016
2017	30,963
2016	60,151
2015	29,246
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	407,943
Other | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
2020	13
2019	0
2018	0
2017	0
2016	0
2015	0
Revolving Loans	79
Revolving Loans Converted to Term Loans	0
Total	$ 92