Collateralized Agreements and Financings - Schedule of Gross Carrying Value of Repurchase Agreements and Securities Loaned (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Offsetting Liabilities [Line Items]
Repurchase agreements	$ 114,013	$ 114,960
Securities loaned	8,871	6,179
Commercial Paper, Certificates of Deposit, Time Deposits and Other Money Market Instruments [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	671	806
U.S. Government and Federal Agency Obligations [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	45,401	54,856
Securities loaned		101
Non-U.S. Government and Agency Obligations [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	39,929	31,547
Securities loaned	1,070	2,465
Securities Backed By Commercial Real Estate [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	9	269
Securities Backed By Residential Real Estate [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	116	2,059
Corporate Debt Securities [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	9,859	6,877
Securities loaned	14	30
State and Municipal Obligations [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	111	609
Other Debt Obligations [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	14	101
Equities and Convertible Debentures [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	17,903	17,836
Securities loaned	$ 7,787	$ 3,583