Guarantee Arrangements and Pledged Assets and Collateral - Summary of Pledged Assets Included in Consolidated Balance Sheet (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Interest bearing deposits with banks	$ 397		$ 415
Trading assets	2,809	[1]	2,886	[1]
Securities available-for-sale	24,794	[2]	22,023	[2]
Securities held to maturity	3,410		3,602
Loans	13,488	[3]	12,580	[3]
Other assets	1,996	[4]	2,495	[4]
Total	$ 46,894		$ 44,001

[1] Trading assets are primarily pledged against liabilities associated with repurchase agreements.

[2] Securities available-for-sale are primarily pledged against derivatives, public fund deposits, trust deposits and various short-term and long term borrowings, as well as providing capacity for potential secured borrowings from the Federal Home Loan Bank of New York ("FHLB") and the Federal Reserve Bank of New York.

[3] Loans are primarily residential mortgage loans pledged against current and potential borrowings from the FHLB and the Federal Reserve Bank of New York.

[4] Other assets represent cash on deposit with non-banks related to derivative collateral support agreements.