Loans and Allowance for Credit Losses - Net Loans (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	$ 30,704	$ 27,925
Allowance for credit losses	(100)	(122)
Loans, net of allowance	30,604	27,803
Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	22,000	21,132
Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	8,704	6,793
Fund Finance | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	12,029	11,531
Fund Finance | Geographic Distribution, Domestic | Real Money Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	6,419	6,391
Fund Finance | Geographic Distribution, Domestic | Private Equity Capital Call Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	8,710	8,380
Fund Finance | Geographic Distribution, Domestic | Business Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,043	821
Fund Finance | Geographic Distribution, Domestic | Collateralized Loan Obligations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,580
Fund Finance | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	6,003	4,432
Leveraged loans | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	3,385	2,923
Leveraged loans | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,169	1,242
Overdrafts | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,196	1,894
Overdrafts | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,532	1,088
Other | Securities Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,406	1,911
Other | Municipal Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	629	754
Other | Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	21	54
Other | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,056	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	2,334	2,096
Commercial real estate | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	$ 2,334	$ 2,096