Loans and Allowance for Credit Losses - Net Loans (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	$ 32,797	$ 27,925
Allowance for credit losses	(95)	(122)
Loans, net of allowance	32,702	27,803
Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	22,650	21,132
Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	10,147	6,793
Fund Finance | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	12,367	11,531
Fund Finance | Geographic Distribution, Domestic | Real Money Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	6,282	6,391
Fund Finance | Geographic Distribution, Domestic | Private Equity Capital Call Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	9,752	8,380
Fund Finance | Geographic Distribution, Domestic | Business Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	993	821
Fund Finance | Geographic Distribution, Domestic | Collateralized Loan Obligations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,412
Fund Finance | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	7,368	4,432
Leveraged loans | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	3,407	2,923
Leveraged loans | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,317	1,242
Overdrafts | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,352	1,894
Overdrafts | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,462	1,088
Other | Securities Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,532	1,911
Other | Municipal Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	589	754
Other | Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	19	54
Other | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,140	2,688
Other | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	0	31
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,384	2,096
Commercial real estate | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	$ 2,384	$ 2,096