Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Summary of the Aging of Loans Broken out by Risk-based Segments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	$ 47,675,166	$ 45,181,488
Loans Past Due 90 Days or More Still Accruing Interest	4,491	0
30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	38,590	60,267
60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	3,079	7,251
Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	6,483	2,200
Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	48,152	69,718
Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	47,627,014	45,111,770
Global Fund Banking
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	27,306,926	25,543,198
Loans Past Due 90 Days or More Still Accruing Interest	4,088	0
Global Fund Banking | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	10,002	27,606
Global Fund Banking | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	3	8
Global Fund Banking | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	4,106	11
Global Fund Banking | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	14,111	27,625
Global Fund Banking | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	27,292,815	25,515,573
Investor dependent
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5,167,069	4,971,818
Loans Past Due 90 Days or More Still Accruing Interest	9	0
Investor dependent | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	17,669	17,667
Investor dependent | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	798	2,078
Investor dependent | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	500	1,109
Investor dependent | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	18,967	20,854
Investor dependent | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5,148,102	4,950,964
Investor dependent | Early stage
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,523,208	1,485,866
Loans Past Due 90 Days or More Still Accruing Interest	9	0
Investor dependent | Early stage | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	6,270	6,320
Investor dependent | Early stage | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	643	1,840
Investor dependent | Early stage | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	500	202
Investor dependent | Early stage | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	7,413	8,362
Investor dependent | Early stage | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,515,795	1,477,504
Investor dependent | Mid stage
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,588,185	1,564,870
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Investor dependent | Mid stage | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	8,127	5,984
Investor dependent | Mid stage | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	155	238
Investor dependent | Mid stage | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	907
Investor dependent | Mid stage | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	8,282	7,129
Investor dependent | Mid stage | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,579,903	1,557,741
Investor dependent | Later stage
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,055,676	1,921,082
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Investor dependent | Later stage | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	3,272	5,363
Investor dependent | Later stage | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Investor dependent | Later stage | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Investor dependent | Later stage | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	3,272	5,363
Investor dependent | Later stage | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,052,404	1,915,719
Cash flow dependent
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	4,944,176	4,934,533
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Cash flow dependent | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	3,839	6,544
Cash flow dependent | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	69	58
Cash flow dependent | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	485	0
Cash flow dependent | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	4,393	6,602
Cash flow dependent | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	4,939,783	4,927,931
Cash flow dependent | Sponsor led buyout
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,984,567	1,989,173
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Cash flow dependent | Sponsor led buyout | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	34
Cash flow dependent | Sponsor led buyout | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Cash flow dependent | Sponsor led buyout | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Cash flow dependent | Sponsor led buyout | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	34
Cash flow dependent | Sponsor led buyout | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,984,567	1,989,139
Cash flow dependent | Other
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,959,609	2,945,360
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Cash flow dependent | Other | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	3,839	6,510
Cash flow dependent | Other | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	69	58
Cash flow dependent | Other | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	485	0
Cash flow dependent | Other | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	4,393	6,568
Cash flow dependent | Other | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,955,216	2,938,792
SVB Private Bank
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5,063,827	4,901,056
Loans Past Due 90 Days or More Still Accruing Interest	0	0
SVB Private Bank | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	4,292
SVB Private Bank | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,973	3,990
SVB Private Bank | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
SVB Private Bank | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,973	8,282
SVB Private Bank | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5,061,854	4,892,774
Balance sheet dependent
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,501,524	2,191,023
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Balance sheet dependent | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	6,962	987
Balance sheet dependent | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	62	1,089
Balance sheet dependent | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Balance sheet dependent | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	7,024	2,076
Balance sheet dependent | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,494,500	2,188,947
Premium wine
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,040,223	1,052,643
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Premium wine | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	3,168
Premium wine | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Premium wine | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	998	998
Premium wine | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	998	4,166
Premium wine | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,039,225	1,048,477
Other
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	45,688	27,687
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Other | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1	3
Other | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	28
Other | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	82
Other | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1	113
Other | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	45,687	27,574
SBA loans
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,605,733	1,559,530
Loans Past Due 90 Days or More Still Accruing Interest	394	0
SBA loans | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	117	0
SBA loans | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	174	0
SBA loans | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	394	0
SBA loans | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	685	0
SBA loans | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	$ 1,605,048	$ 1,559,530