Commitments and Contingent Liabilities- Summary of Off-Balance Sheet Credit Risks, Net of Participations (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Securities lending indemnifications joint venture	$ 68,000,000,000		$ 64,000,000,000
Lending commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off balance sheet credit risk	34,166,000,000		33,273,000,000
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off balance sheet credit risk	5,600,000,000	[1]	5,767,000,000	[1]
Off-balance sheet credit risks participations	961,000,000		894,000,000
Commercial letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off balance sheet credit risk	264,000,000		255,000,000
Securities lending indemnifications
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off balance sheet credit risk	$ 310,273,000,000	[2]	$ 304,386,000,000	[2]

[1] Net of participations totaling $961 million at March 31, 2015 and $894 million at Dec. 31, 2014.

[2] Excludes the indemnification for securities for which BNY Mellon acts as an agent on behalf of CIBC Mellon clients, which totaled $68 billion at March 31, 2015 and $64 billion at Dec. 31, 2014.