Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Pledged Assets Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Interest bearing deposits with banks		$ 3,040	$ 2,952
Trading assets	[1]	2,986	3,185
Securities available-for-sale	[2]	7,043	7,210
Securities held to maturity	[2]	1,894	2,131
Loans	[3]	16,489	17,404
Other assets	[4]	2,566	2,253
Total		$ 34,018	$ 35,135

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

[2] Securities 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.