Collateralized Agreements and Financings - Other Secured Financings (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	$ 13,218	$ 7,195
Other Secured Financings Short Term At Amortized Cost		129
Other Secured Financings Long Term At Fair Value	10,908	10,876
Other Secured Financings Long Term At Amortized Cost	1,629	1,077
Total other secured financings	25,755	19,277
Other secured financings collateralized by financial instruments	16,909	12,015
Other secured financings collateralized by other assets	8,846	7,262
U.S. Dollar [Member]
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	6,371	2,754
Other Secured Financings Short Term At Amortized Cost		129
Other Secured Financings Long Term At Fair Value	6,632	7,402
Other Secured Financings Long Term At Amortized Cost	914	397
Total other secured financings	13,917	10,682
Other secured financings collateralized by financial instruments	6,841	4,826
Other secured financings collateralized by other assets	7,076	5,856
Non-U.S. Dollar [Member]
Other Secured Financings [Line Items]
Other Secured Financings Short Term At Fair Value	6,847	4,441
Other Secured Financings Long Term At Fair Value	4,276	3,474
Other Secured Financings Long Term At Amortized Cost	715	680
Total other secured financings	11,838	8,595
Other secured financings collateralized by financial instruments	10,068	7,189
Other secured financings collateralized by other assets	$ 1,770	$ 1,406