Derivative Instruments- Additional Information (Detail) (USD $)	3 Months Ended					3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014 Securities available-for-sale	Dec. 31, 2013 Securities available-for-sale	Mar. 31, 2014 Long-term debt	Dec. 31, 2013 Long-term debt	Mar. 31, 2014 Interest Rate Swap Securities available-for-sale	Mar. 31, 2014 Interest Rate Swap Long-term debt	Mar. 31, 2014 Foreign exchange contracts	Mar. 31, 2014 Interest rate contracts	Mar. 31, 2014 Cash flow hedges Foreign exchange contracts	Mar. 31, 2014 Cash flow hedges Foreign exchange contracts Fair Value Hedge	Mar. 31, 2014 Cash flow hedges Foreign exchange contracts Fair Value Hedge Maximum	Mar. 31, 2014 Net Investment Hedging Foreign exchange contracts
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Original maturities, maximum (in years) of hedged instruments						30 years	30 years
Hedged financial instruments		$ 6,600,000,000		$ 14,700,000,000
Hedged financial instruments, notional amount of derivative		6,774,000,000	6,647,000,000	14,650,000,000	14,755,000,000	6,800,000,000	14,700,000,000			280,000,000	1,500,000,000		6,100,000,000
Derivative Instruments, Gain Recognized in Other Comprehensive Income (Loss), Effective Portion										8,000,000		1,000,000
Original maturities, minimum (in years) of hedged instruments							5 years
Hedging derivatives, maturities, maximum (in months or in years)										9 months	9 months		2 years
Non-derivative financial instruments designated as hedges of net investments in foreign subsidiaries were all long-term liabilities of BNY Mellon in various currencies	544,000,000
Notional amount of derivatives that will mature within one year								456,000,000,000	476,000,000,000
Notional amount of derivatives that will mature between one and five years								9,000,000,000	160,000,000,000
Notional amount of derivatives that will mature after 5 years								8,000,000,000	149,000,000,000
Value-at-risk methodology assumed holding period for instruments (in days)	1 day
Value-at-risk methodology confidence level percentage (percent)	99.00%
Additional collateral the Company would have to post for existing collateral arrangements, if the company's debt rating had fallen below investment grade	$ 465,000,000