Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Pledged Assets Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Interest bearing deposits with banks	[1]	$ 1,138	$ 2,158
Trading assets	[2]	1,115	1,265
Securities available-for-sale	[3]	8,781	8,652
Securities held to maturity	[3]	917	1,076
Loans	[4]	18,938	18,146
Other assets	[5]	1,566	2,352
Total		$ 32,455	$ 33,649

[1] Represents gross amount of cash on deposit with banks related to derivative collateral-support agreements, of which a majority has been netted against derivative liabilities on the consolidated balance sheet.

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

[3] 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.

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

[5] Represents gross amount of cash on deposit with non-banks related to derivative collateral support agreements, of which a majority has been netted against derivative liabilities on the consolidated balance sheet.