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 Millions	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	$ 50,754	$ 45,181
Loans Past Due 90 Days or More Still Accruing Interest	3	0
30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	10	59
60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	6	7
Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	4	2
Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	20	68
Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	50,734	45,113
Global Fund Banking
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	30,630	25,543
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Global Fund Banking | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	28
Global Fund Banking | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Global Fund Banking | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Global Fund Banking | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	28
Global Fund Banking | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	30,630	25,515
Investor dependent
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5,328	4,972
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Investor dependent | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	17
Investor dependent | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	2
Investor dependent | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1	1
Investor dependent | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5	20
Investor dependent | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5,323	4,952
Investor dependent | Early stage
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,565	1,486
Loans Past Due 90 Days or More Still Accruing Interest	0	0
Investor dependent | Early stage | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1	6
Investor dependent | Early stage | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	2
Investor dependent | Early stage | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1	0
Investor dependent | Early stage | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	8
Investor dependent | Early stage | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,563	1,478
Investor dependent | Mid stage
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,708	1,565
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	0	6
Investor dependent | Mid stage | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	0
Investor dependent | Mid stage | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	1
Investor dependent | Mid stage | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	7
Investor dependent | Mid stage | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,706	1,558
Investor dependent | Later stage
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,055	1,921
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	1	5
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	1	5
Investor dependent | Later stage | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,054	1,916
Cash flow dependent
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	4,843	4,934
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	5	6
Cash flow dependent | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Cash flow dependent | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Cash flow dependent | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5	6
Cash flow dependent | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	4,838	4,928
Cash flow dependent | Sponsor led buyout
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,917	1,989
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	0
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	0
Cash flow dependent | Sponsor led buyout | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,917	1,989
Cash flow dependent | Other
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,926	2,945
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	5	6
Cash flow dependent | Other | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Cash flow dependent | Other | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Cash flow dependent | Other | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5	6
Cash flow dependent | Other | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,921	2,939
Private bank
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5,297	4,901
Loans Past Due 90 Days or More Still Accruing Interest	2	0
Private bank | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	4
Private bank | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	4
Private bank | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	0
Private bank | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	8
Private bank | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	5,295	4,893
Balance sheet dependent
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,804	2,191
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	1	1
Balance sheet dependent | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	3	1
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	4	2
Balance sheet dependent | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2,800	2,189
Premium wine
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,002	1,053
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	2	3
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	0	1
Premium wine | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	4
Premium wine | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1,000	1,049
Other
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	7	28
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	0	0
Other | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Other | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Other | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
Other | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	7	28
SBA loans
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	843	1,559
Loans Past Due 90 Days or More Still Accruing Interest	1	0
SBA loans | 30 - 59   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	0	0
SBA loans | 60 - 89   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1	0
SBA loans | Equal to or Greater Than 90   Days Past   Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	1	0
SBA loans | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	2	0
SBA loans | Current
Financing Receivable, Past Due [Line Items]
Loans, amortized cost	$ 841	$ 1,559