Business Segments - Segment Operating Results (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Non-interest revenues	$ 9,697	$ 7,315	$ 29,478	$ 23,294
Net interest income	1,084	1,008	3,341	3,297
Total net revenues	10,781	8,323	32,819	26,591
Provision for credit losses	278	291	2,805	729
Operating expenses	6,204	5,616	23,076	17,600
Pre-tax earnings	4,299	2,416	6,938	8,262
Net earnings	3,367	1,877	4,953	6,549
Net earnings to common	3,233	1,793	4,553	6,173
Average common equity	$ 79,739	$ 79,851	$ 79,840	$ 79,062
Return on average common equity	16.20%	9.00%	7.60%	10.40%
Investment Banking [Member]
Segment Reporting Information [Line Items]
Non-interest revenues	$ 1,904	$ 1,698	$ 6,614	$ 5,157
Net interest income	65	143	196	378
Total net revenues	1,969	1,841	6,810	5,535
Provision for credit losses	171	91	1,612	258
Operating expenses	1,067	972	4,940	3,027
Pre-tax earnings	731	778	258	2,250
Net earnings	469	607	184	1,784
Net earnings to common	452	597	133	1,738
Average common equity	$ 11,271	$ 12,471	$ 11,251	$ 11,166
Return on average common equity	16.00%	19.10%	1.60%	20.80%
Global Markets [Member]
Segment Reporting Information [Line Items]
Non-interest revenues	$ 4,093	$ 3,227	$ 15,292	$ 9,943
Net interest income	460	316	1,600	1,356
Total net revenues	4,553	3,543	16,892	11,299
Provision for credit losses	(15)	16	236	15
Operating expenses	2,542	2,377	10,568	7,810
Pre-tax earnings	2,026	1,150	6,088	3,474
Net earnings	1,904	895	4,346	2,753
Net earnings to common	1,816	839	4,085	2,499
Average common equity	$ 39,960	$ 38,847	$ 40,542	$ 40,670
Return on average common equity	18.20%	8.60%	13.40%	8.20%
Asset Management [Member]
Segment Reporting Information [Line Items]
Non-interest revenues	$ 2,717	$ 1,497	$ 4,626	$ 5,616
Net interest income	51	124	147	346
Total net revenues	2,768	1,621	4,773	5,962
Provision for credit losses	70	81	420	154
Operating expenses	1,358	1,176	3,888	3,526
Pre-tax earnings	1,340	364	465	2,282
Net earnings	858	278	332	1,809
Net earnings to common	839	264	273	1,753
Average common equity	$ 19,989	$ 22,320	$ 20,332	$ 21,199
Return on average common equity	16.80%	4.70%	1.80%	11.00%
Consumer & Wealth Management [Member]
Segment Reporting Information [Line Items]
Non-interest revenues	$ 983	$ 893	$ 2,946	$ 2,578
Net interest income	508	425	1,398	1,217
Total net revenues	1,491	1,318	4,344	3,795
Provision for credit losses	52	103	537	302
Operating expenses	1,237	1,091	3,680	3,237
Pre-tax earnings	202	124	127	256
Net earnings	136	97	91	203
Net earnings to common	126	93	62	183
Average common equity	$ 8,519	$ 6,213	$ 7,715	$ 6,027
Return on average common equity	5.90%	6.00%	1.10%	4.00%