Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Pledged Assets Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Interest bearing deposits with banks		$ 3,121	$ 3,225
Trading assets	[1]	4,802	2,465
Securities available-for-sale	[2]	8,703	7,440
Securities held to maturity	[2]	1,935	1,747
Loans	[3]	16,262	18,189
Other assets	[4]	3,937	2,289
Total		$ 38,760	$ 35,355

[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 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.