Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Activity Relating to our Allowance for Credit Losses for Loans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Increase in allowance for credit loss	$ 4
Allowance for credit loss, beginning balance	392	$ 549	$ 448	$ 305
Charge-offs	(15)	(15)	(110)	(52)
Recoveries	3	4	8	12
Provision (Reduction) for Credit Losses	16	52	50	301
Foreign Currency Translation Adjustments				(1)
Allowance for credit loss, ending balance	396	590	396	590
Accrued interest receivable and other assets | Loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable	143		143		$ 126
Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				25
Investor dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	168	276	213	82
Charge-offs	(6)	(6)	(20)	(39)
Recoveries	3	4	8	9
Provision (Reduction) for Credit Losses	(7)	18	(43)	170
Foreign Currency Translation Adjustments				(2)
Allowance for credit loss, ending balance	158	292	158	292
Investor dependent | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				72
Investor dependent | Early stage
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	62	127	86	26
Charge-offs	(5)	(2)	(19)	(12)
Recoveries	2	3	3	4
Provision (Reduction) for Credit Losses	(4)	20	(15)	91
Foreign Currency Translation Adjustments				(1)
Allowance for credit loss, ending balance	55	148	55	148
Investor dependent | Early stage | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				40
Investor dependent | Growth Stage
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	106	149	127	56
Charge-offs	(1)	(4)	(1)	(27)
Recoveries	1	1	5	5
Provision (Reduction) for Credit Losses	(3)	(2)	(28)	79
Foreign Currency Translation Adjustments				(1)
Allowance for credit loss, ending balance	103	144	103	144
Investor dependent | Growth Stage | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				32
Private bank
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	44	88	53	22
Charge-offs	(2)	(1)	(2)	(2)
Recoveries	0	0	0	0
Provision (Reduction) for Credit Losses	5	4	(4)	59
Foreign Currency Translation Adjustments				0
Allowance for credit loss, ending balance	47	91	47	91
Private bank | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				12
Global Fund Banking
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	60	57	46	107
Charge-offs	0	0	(80)	0
Recoveries	0	0	0	0
Provision (Reduction) for Credit Losses	6	(3)	100	17
Foreign Currency Translation Adjustments				0
Allowance for credit loss, ending balance	66	54	66	54
Global Fund Banking | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				(70)
Cash Flow And Balance Sheet Dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	112	104	125	81
Charge-offs	(7)	(8)	(7)	(11)
Recoveries	0	0	0	3
Provision (Reduction) for Credit Losses	14	27	1	51
Foreign Currency Translation Adjustments				0
Allowance for credit loss, ending balance	119	123	119	123
Cash Flow And Balance Sheet Dependent | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				(1)
Premium Wine And Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	8	24	9	13
Charge-offs	0	0	(1)	0
Recoveries	0	0	0	0
Provision (Reduction) for Credit Losses	(2)	2	(2)	0
Foreign Currency Translation Adjustments				1
Allowance for credit loss, ending balance	6	26	6	26
Premium Wine And Other | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				12
SBA loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		0	2	0
Charge-offs		0	0	0
Recoveries		0	0	0
Provision (Reduction) for Credit Losses		4	(2)	4
Foreign Currency Translation Adjustments				0
Allowance for credit loss, ending balance	$ 0	$ 4	$ 0	4
SBA loans | Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance				$ 0