Commitments and Contingent Liabilities- Significant Industry Concentrations Related to Credit Exposure (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	$ 62,326,000,000	[1]	$ 59,132,000,000	[1]
Financial institutions
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	14,667,000,000		13,319,000,000
Unfunded commitments	16,000,000,000
Total exposure	30,700,000,000
Financial institutions | Banks
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	9,100,000,000
Unfunded commitments	1,700,000,000
Total exposure	10,800,000,000
Financial institutions | Asset managers
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1,700,000,000
Unfunded commitments	5,100,000,000
Total exposure	6,800,000,000
Financial institutions | Securities industry
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	3,300,000,000
Unfunded commitments	1,100,000,000
Total exposure	4,400,000,000
Financial institutions | Insurance
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	100,000,000
Unfunded commitments	3,900,000,000
Total exposure	4,000,000,000
Financial institutions | Government
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	100,000,000
Unfunded commitments	3,000,000,000
Total exposure	3,100,000,000
Financial institutions | Other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	400,000,000
Unfunded commitments	1,200,000,000
Total exposure	1,600,000,000
Commercial
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1,971,000,000		1,642,000,000
Unfunded commitments	18,700,000,000
Total exposure	20,700,000,000
Commercial | Services and other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	800,000,000
Unfunded commitments	6,000,000,000
Total exposure	6,800,000,000
Commercial | Manufacturing
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	400,000,000
Unfunded commitments	5,700,000,000
Total exposure	6,100,000,000
Commercial | Energy and utilities
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	500,000,000
Unfunded commitments	5,500,000,000
Total exposure	6,000,000,000
Commercial | Media and telecom
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	300,000,000
Unfunded commitments	1,500,000,000
Total exposure	$ 1,800,000,000

[1] Net of unearned income of $843 million at March 31, 2015 and $866 million at Dec. 31, 2014 primarily on domestic and foreign lease financings.