Collateralized Agreements and Financings - Other Secured Financings (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	$ 15,185	$ 13,400
Other Secured Financings Short Term At Amortized Cost	3	833
Other Secured Financings Long Term At Fair Value	6,821	9,807
Other Secured Financings Long Term At Amortized Cost	469	713
Other secured financings	22,478	24,753
Other secured financings collateralized by financial instruments	20,931	23,734
Other secured financings collateralized by other assets	1,547	1,019
U.S. Dollar [Member]
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	10,417	7,952
Other Secured Financings Short Term At Amortized Cost	$ 3	$ 514
Weighted average interest rate, after giving effect to hedging activities, on other secured financings at amortized cost (short-term)	4.33%	2.93%
Other Secured Financings Long Term At Fair Value	$ 5,689	$ 6,702
Other Secured Financings Long Term At Amortized Cost	$ 145	$ 370
Weighted average interest rate, after giving effect to hedging activities, on other secured financings at amortized cost (long-term)	3.98%	2.87%
Other secured financings	$ 16,254	$ 15,538
Other secured financings collateralized by financial instruments	15,198	14,862
Other secured financings collateralized by other assets	1,056	676
Non-U.S. Dollar [Member]
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	4,768	5,448
Other Secured Financings Short Term At Amortized Cost		$ 319
Weighted average interest rate, after giving effect to hedging activities, on other secured financings at amortized cost (short-term)		3.83%
Other Secured Financings Long Term At Fair Value	1,132	$ 3,105
Other Secured Financings Long Term At Amortized Cost	$ 324	$ 343
Weighted average interest rate, after giving effect to hedging activities, on other secured financings at amortized cost (long-term)	1.96%	1.54%
Other secured financings	$ 6,224	$ 9,215
Other secured financings collateralized by financial instruments	5,733	8,872
Other secured financings collateralized by other assets	$ 491	$ 343