Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Credit Quality Indicators, Broken out by Risk-Based Segments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	$ 36,727,222	$ 33,164,636
Loans, at gross basis		33,327,704
Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	94,326
Loans, at gross basis		102,669
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	35,128,848
Loans, at gross basis		32,361,879
Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,504,048
Loans, at gross basis		863,156
Private equity/venture capital
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	17,901,117	17,696,794
Loans, at gross basis		17,712,797
Private equity/venture capital | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	9
Loans, at gross basis		0
Private equity/venture capital | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	17,892,840
Loans, at gross basis		17,708,550
Private equity/venture capital | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	8,268
Loans, at gross basis		4,247
Investor dependent
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	5,138,876	4,335,195
Loans, at gross basis		4,418,884
Investor dependent | Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,797,576	1,624,221
Loans, at gross basis		1,653,425
Investor dependent | Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,435,772	1,047,398
Loans, at gross basis		1,066,783
Investor dependent | Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,905,528	1,663,576
Loans, at gross basis		1,698,676
Investor dependent | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	43,039
Loans, at gross basis		34,719
Investor dependent | Nonperforming (Nonaccrual) | Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	24,422
Loans, at gross basis		11,093
Investor dependent | Nonperforming (Nonaccrual) | Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	8,119
Loans, at gross basis		17,330
Investor dependent | Nonperforming (Nonaccrual) | Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	10,498
Loans, at gross basis		6,296
Investor dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,527,816
Loans, at gross basis		3,850,585
Investor dependent | Pass | Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,549,222
Loans, at gross basis		1,436,022
Investor dependent | Pass | Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,259,442
Loans, at gross basis		924,002
Investor dependent | Pass | Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,719,152
Loans, at gross basis		1,490,561
Investor dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	568,021
Loans, at gross basis		533,580
Investor dependent | Criticized | Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	223,932
Loans, at gross basis		206,310
Investor dependent | Criticized | Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	168,211
Loans, at gross basis		125,451
Investor dependent | Criticized | Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	175,878
Loans, at gross basis		201,819
Cash flow dependent
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,845,246	4,424,238
Loans, at gross basis		4,455,867
Cash flow dependent | Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	2,057,439	2,185,497
Loans, at gross basis		2,203,020
Cash flow dependent | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	2,787,807	2,238,741
Loans, at gross basis		2,252,847
Cash flow dependent | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	26,975
Loans, at gross basis		62,266
Cash flow dependent | Nonperforming (Nonaccrual) | Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	21,658
Loans, at gross basis		44,585
Cash flow dependent | Nonperforming (Nonaccrual) | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	5,317
Loans, at gross basis		17,681
Cash flow dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,260,629
Loans, at gross basis		4,181,613
Cash flow dependent | Pass | Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,819,253
Loans, at gross basis		2,039,847
Cash flow dependent | Pass | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	2,441,376
Loans, at gross basis		2,141,766
Cash flow dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	557,642
Loans, at gross basis		211,988
Cash flow dependent | Criticized | Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	216,528
Loans, at gross basis		118,588
Cash flow dependent | Criticized | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	341,114
Loans, at gross basis		93,400
SVB Private Bank
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	3,816,277	3,492,269
Loans, at gross basis		3,489,219
SVB Private Bank | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	6,517
Loans, at gross basis		5,480
SVB Private Bank | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	3,787,830
Loans, at gross basis		3,472,138
SVB Private Bank | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	21,930
Loans, at gross basis		11,601
Balance sheet dependent
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,693,071	1,286,153
Loans, at gross basis		1,297,304
Balance sheet dependent | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	11,842
Loans, at gross basis		0
Balance sheet dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,588,207
Loans, at gross basis		1,231,961
Balance sheet dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	93,022
Loans, at gross basis		65,343
Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,039,456	1,062,264
Loans, at gross basis		1,063,512
Premium wine | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,681
Loans, at gross basis		204
Premium wine | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	926,549
Loans, at gross basis		1,026,973
Premium wine | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	111,226
Loans, at gross basis		36,335
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	457,234	867,723
Loans, at gross basis		890,121
Other | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	61
Loans, at gross basis		0
Other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	456,947
Loans, at gross basis		890,059
Other | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	226
Loans, at gross basis		62
SBA loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,835,945	$ 0
SBA loans | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,202
SBA loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,688,030
SBA loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	$ 143,713