Loans and Allowance for Credit Losses - Net Loans (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	$ 27,925	$ 26,309
Allowance for credit losses	(122)	(74)	$ (67)	$ (54)
Loans, net of allowance	27,803	26,235
Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	21,132	20,528
Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	6,793	5,781
Fund Finance | Securities Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,911	2,537
Fund Finance | Municipal Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	754	848
Fund Finance | Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	54	26
Fund Finance | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	11,531	10,270
Fund Finance | Geographic Distribution, Domestic | 40 Act Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	6,391	6,040
Fund Finance | Geographic Distribution, Domestic | Business Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	821	932
Fund Finance | Geographic Distribution, Domestic | Private Equity Capital Call Finance Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	8,380	6,076
Fund Finance | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	4,432	3,145
Leveraged loans | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,923	3,342
Leveraged loans | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,242	1,119
Overdrafts | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,894	1,739
Overdrafts | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	1,088	1,517
Other | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,688	3,411
Other | Non-U.S.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	31	0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	2,096
Commercial real estate | Geographic Distribution, Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross	$ 2,096	$ 1,766