Business Segments - Segment Operating Results (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net revenues	$ 8,168	$ 6,861	$ 22,438	$ 26,547
Operating expenses	5,300	4,815	15,531	18,841
Pre-tax earnings	2,868	2,046	6,907	7,706
Total assets	879,987	880,559	879,987	880,559	$ 896,843	$ 861,395
Investment Banking - Financial Advisory [Member]
Segment Reporting Information [Line Items]
Net revenues	658	809	2,223	2,591
Investment Banking - Equity Underwriting [Member]
Segment Reporting Information [Line Items]
Net revenues	227	190	679	1,318
Investment Banking - Debt Underwriting [Member]
Segment Reporting Information [Line Items]
Net revenues	652	557	1,885	1,571
Investment Banking - Underwriting [Member]
Segment Reporting Information [Line Items]
Net revenues	879	747	2,564	2,889
Investment Banking [Member]
Segment Reporting Information [Line Items]
Net revenues	1,537	1,556	4,787	5,480
Operating expenses	863	788	2,720	3,049
Pre-tax earnings	674	768	2,067	2,431
Total assets	2,245	2,515	2,245	2,515
Institutional Client Services - Fixed Income, Currency and Commodities Client Execution [Member]
Segment Reporting Information [Line Items]
Net revenues	1,964	1,461	5,554	6,199
Institutional Client Services - Equities Client Execution [Member]
Segment Reporting Information [Line Items]
Net revenues	678	555	1,735	2,466
Institutional Client Services - Commissions and Fees [Member]
Segment Reporting Information [Line Items]
Net revenues	719	818	2,342	2,393
Institutional Client Services - Securities Services [Member]
Segment Reporting Information [Line Items]
Net revenues	387	379	1,241	1,215
Institutional Client Services - Equities [Member]
Segment Reporting Information [Line Items]
Net revenues	1,784	1,752	5,318	6,074
Institutional Client Services [Member]
Segment Reporting Information [Line Items]
Net revenues	3,748	3,213	10,872	12,273
Operating expenses	2,526	2,522	7,649	10,101
Pre-tax earnings	1,222	691	3,223	2,172
Total assets	667,105	700,548	667,105	700,548
Investing and Lending - Equity Securities [Member]
Segment Reporting Information [Line Items]
Net revenues	920	370	1,546	2,784
Investing and Lending - Debt Securities and Loans [Member]
Segment Reporting Information [Line Items]
Net revenues	478	300	1,050	1,356
Investing and Lending [Member]
Segment Reporting Information [Line Items]
Net revenues	1,398	670	2,596	4,140
Operating expenses	690	358	1,714	1,948
Pre-tax earnings	708	312	882	2,192
Total assets	195,774	162,444	195,774	162,444
Investment Management - Management and Other Fees [Member]
Segment Reporting Information [Line Items]
Net revenues	1,225	1,212	3,571	3,651
Investment Management - Incentive Fees [Member]
Segment Reporting Information [Line Items]
Net revenues	114	73	197	590
Investment Management - Transaction Revenues [Member]
Segment Reporting Information [Line Items]
Net revenues	146	137	415	413
Investment Management [Member]
Segment Reporting Information [Line Items]
Net revenues	1,485	1,422	4,183	4,654
Operating expenses	1,221	1,122	3,448	3,718
Pre-tax earnings	264	300	735	936
Total assets	$ 14,863	$ 15,052	$ 14,863	$ 15,052