Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Credit Quality Indicators, Broken out by Risk-Based Segments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	$ 38,413,891	$ 33,164,636
Loans, at gross basis		33,327,704
Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	105,711
Loans, at gross basis		102,669
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	36,874,725
Loans, at gross basis		32,361,879
Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,433,455
Loans, at gross basis		863,156
Global fund banking
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	19,584,518	17,696,794
Loans, at gross basis		17,712,797
Global fund banking | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	13
Loans, at gross basis		0
Global fund banking | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	19,576,723
Loans, at gross basis		17,708,550
Global fund banking | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	7,782
Loans, at gross basis		4,247
Investor dependent
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	5,111,669	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	1,470,941	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	1,626,794	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	2,013,934	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	69,934
Loans, at gross basis		34,719
Investor dependent | Nonperforming (Nonaccrual) | Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	19,732
Loans, at gross basis		11,093
Investor dependent | Nonperforming (Nonaccrual) | Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	11,627
Loans, at gross basis		17,330
Investor dependent | Nonperforming (Nonaccrual) | Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	38,575
Loans, at gross basis		6,296
Investor dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,541,543
Loans, at gross basis		3,850,585
Investor dependent | Pass | Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,296,789
Loans, at gross basis		1,436,022
Investor dependent | Pass | Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,449,525
Loans, at gross basis		924,002
Investor dependent | Pass | Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,795,229
Loans, at gross basis		1,490,561
Investor dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	500,192
Loans, at gross basis		533,580
Investor dependent | Criticized | Early stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	154,420
Loans, at gross basis		206,310
Investor dependent | Criticized | Mid stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	165,642
Loans, at gross basis		125,451
Investor dependent | Criticized | Later stage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	180,130
Loans, at gross basis		201,819
Cash flow dependent
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,662,400	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	2,062,243	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	2,600,157	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	27,877
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	21,592
Loans, at gross basis		44,585
Cash flow dependent | Nonperforming (Nonaccrual) | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	6,285
Loans, at gross basis		17,681
Cash flow dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,142,396
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	1,827,943
Loans, at gross basis		2,039,847
Cash flow dependent | Pass | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	2,314,453
Loans, at gross basis		2,141,766
Cash flow dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	492,127
Loans, at gross basis		211,988
Cash flow dependent | Criticized | Sponsor led buyout
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	212,708
Loans, at gross basis		118,588
Cash flow dependent | Criticized | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	279,419
Loans, at gross basis		93,400
SVB Private Bank
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,424,899	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	5,432
Loans, at gross basis		5,480
SVB Private Bank | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	4,395,531
Loans, at gross basis		3,472,138
SVB Private Bank | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	23,936
Loans, at gross basis		11,601
Balance sheet dependent
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,698,220	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	676
Loans, at gross basis		0
Balance sheet dependent | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,565,597
Loans, at gross basis		1,231,961
Balance sheet dependent | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	131,947
Loans, at gross basis		65,343
Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,081,963	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	1,675
Loans, at gross basis		204
Premium wine | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	941,511
Loans, at gross basis		1,026,973
Premium wine | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	138,777
Loans, at gross basis		36,335
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	48,206	867,723
Loans, at gross basis		890,121
Other | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	104
Loans, at gross basis		0
Other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	48,041
Loans, at gross basis		890,059
Other | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	61
Loans, at gross basis		62
SBA loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,802,016	$ 0
SBA loans | Nonperforming (Nonaccrual)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	0
SBA loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	1,663,383
SBA loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, at amortized cost	$ 138,633