Derivative instruments - Narrative (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Counterparty default losses recorded	$ 0
Non-derivative financial instruments designated as hedges of net investments in foreign subsidiaries were all long-term liabilities of BNY Mellon in various currencies				$ 0
Gain or (loss) recognized in income on derivatives	7,000,000	$ 3,000,000	$ 2,000,000	$ 10,000,000	$ 12,000,000
Value-at-risk methodology assumed holding period for instruments				1 day
Value-at-risk methodology confidence level percentage				99.00%
Additional collateral The Bank of New York Mellon would have to post for existing collateral arrangements, if The Bank of New York Mellon had fallen below investment grade	146,000,000			$ 146,000,000		$ 71,000,000
Foreign exchange contracts | Net investment hedging
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Hedged financial instruments, notional amount of derivative	8,600,000,000			8,600,000,000
Foreign exchange contracts | Forecasted Foreign Currency
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Gain (loss) to be reclassified in next 12 months from AOCI to earnings				(8,000,000)
Foreign exchange contracts | Forecasted Foreign Currency | Cash flow hedges
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Hedged financial instruments, notional amount of derivative	343,000,000			$ 343,000,000
Original maturities, maximum, of hedged instruments				12 months
Pre-tax gain (loss) recognized in OCI related to cash flow hedges				$ (8,000,000)
Foreign Exchange Forward
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Hedging derivatives, maturities, maximum				1 year
Securities available-for-sale | Interest rate swap
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Hedged financial instruments	30,400,000,000			$ 30,400,000,000
Hedged financial instruments, notional amount of derivative	30,400,000,000			30,400,000,000
Securities available-for-sale | Foreign Exchange Forward
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Hedged financial instruments	125,000,000			125,000,000
Hedged financial instruments, notional amount of derivative	125,000,000			125,000,000
Long-term debt | Interest rate swap
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Hedged financial instruments	22,200,000,000			22,200,000,000
Hedged financial instruments, notional amount of derivative	22,200,000,000			$ 22,200,000,000
Original maturities, minimum, of hedged instruments				5 years
Original maturities, maximum, of hedged instruments				30 years
Not Designated as Hedging Instrument, Economic Hedge | Equity Swap
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Gain or (loss) recognized in income on derivatives	$ (30,000,000)	$ (13,000,000)	$ 13,000,000	$ (43,000,000)	$ 23,000,000