Guarantee Arrangements and Pledged Assets and Collateral - Summary of Pledged Assets Included in Consolidated Balance Sheet (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Interest bearing deposits with banks	$ 415		$ 355
Trading assets	2,886	[1]	1,296	[1]
Securities available-for-sale	22,023	[2]	21,718	[2]
Securities held to maturity	3,602		363
Loans	12,580	[3]	11,593	[3]
Other assets	2,495	[4]	2,904	[4]
Total	$ 44,001		$ 38,229

[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 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.