Collateralized Agreements and Financings - Other Secured Financings (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	$ 10,940	$ 13,118
Other Secured Financings Short Term At Amortized Cost	309
Other Secured Financings Long Term At Fair Value	11,020	7,955
Other Secured Financings Long Term At Amortized Cost	107	450
Other secured financings	22,376	21,523
Other secured financings collateralized by financial instruments	19,780	19,832
Other secured financings collateralized by other assets	2,596	1,691
U.S. Dollar [Member]
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	5,528	9,380
Other Secured Financings Long Term At Fair Value	7,015	5,562
Other Secured Financings Long Term At Amortized Cost	$ 107	$ 145
Weighted average interest rate, after giving effect to hedging activities, on other secured financings at amortized cost (long-term)	3.99%	4.06%
Other secured financings	$ 12,650	$ 15,087
Other secured financings collateralized by financial instruments	11,195	13,858
Other secured financings collateralized by other assets	1,455	1,229
Non-U.S. Dollar [Member]
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	5,412	3,738
Other Secured Financings Short Term At Amortized Cost	$ 309
Weighted average interest rate, after giving effect to hedging activities, on other secured financings at amortized cost (short-term)	2.27%
Other Secured Financings Long Term At Fair Value	$ 4,005	2,393
Other Secured Financings Long Term At Amortized Cost		$ 305
Weighted average interest rate, after giving effect to hedging activities, on other secured financings at amortized cost (long-term)		2.16%
Other secured financings	9,726	$ 6,436
Other secured financings collateralized by financial instruments	8,585	5,974
Other secured financings collateralized by other assets	$ 1,141	$ 462