Collateralized Agreements and Financings - Schedule 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
No Stated Maturity and Overnight [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	33,885
Securities loaned	4,350
2 - 30 Days [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	37,689
Securities loaned	2,546
31 - 90 Days [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	10,647
Securities loaned	725
91 Days - 1 Year [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	23,091
Securities loaned	1,250
Greater than 1 Year [Member]
Offsetting Liabilities [Line Items]
Repurchase agreements	$ 8,701