Derivative Instruments - Derivatives Netting (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	$ 530,121	$ 547,995
Amounts netted on the Consolidated balance sheets	(483,086)	(503,030)
Net derivative receivables	47,035	44,965
Derivative receivables where an appropriate legal opinion has not been either sought or obtained	13,027	11,558
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	543,148	559,553
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	60,062	56,523
Collateral not nettable on the Consolidated balance sheets	(13,826)	(13,363)
Net amounts	46,236	43,160
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	497,126	521,133
Amounts netted on the Consolidated balance sheets	(467,713)	(493,029)
Net derivative payables	29,413	28,104
Derivative payables where an appropriate legal opinion has not been either sought or obtained	12,280	9,673
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	509,406	530,806
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	41,693	37,777
Collateral not nettable on the Consolidated balance sheets	(3,566)	(4,180)
Net amounts	38,127	33,597
Net cash collateral receivables	55,500	55,500
Net cash collateral payables	40,100	45,500
Interest rate contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	257,993	312,285
Amounts netted on the Consolidated balance sheets	(238,062)	(291,319)
Net derivative receivables	19,931	20,966
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	261,459	315,992
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	23,397	24,673
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	232,821	283,091
Amounts netted on the Consolidated balance sheets	(227,142)	(277,306)
Net derivative payables	5,679	5,785
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	234,233	284,436
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	7,091	7,129
Interest rate contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	250,181	305,569
Amounts netted on the Consolidated balance sheets	(230,533)	(284,917)
Net derivative receivables	19,648	20,652
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	225,999	276,960
Amounts netted on the Consolidated balance sheets	(220,369)	(271,294)
Net derivative payables	5,630	5,666
Interest rate contracts | OTC–cleared
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	7,512	6,531
Amounts netted on the Consolidated balance sheets	(7,374)	(6,318)
Net derivative receivables	138	213
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	6,650	6,004
Amounts netted on the Consolidated balance sheets	(6,618)	(5,928)
Net derivative payables	32	76
Interest rate contracts | Exchange-traded
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	300	185
Amounts netted on the Consolidated balance sheets	(155)	(84)
Net derivative receivables	145	101
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	172	127
Amounts netted on the Consolidated balance sheets	(155)	(84)
Net derivative payables	17	43
Net credit derivatives
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	23,308	22,615
Amounts netted on the Consolidated balance sheets	(22,923)	(22,335)
Net derivative receivables	385	280
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	23,505	23,205
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	582	869
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	23,195	22,995
Amounts netted on the Consolidated balance sheets	(21,908)	(21,954)
Net derivative payables	1,287	1,041
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	23,360	23,252
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	1,452	1,299
Net credit derivatives | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	12,502	15,390
Amounts netted on the Consolidated balance sheets	(12,153)	(15,165)
Net derivative receivables	349	225
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	13,133	16,194
Amounts netted on the Consolidated balance sheets	(11,852)	(15,170)
Net derivative payables	1,281	1,024
Net credit derivatives | OTC–cleared
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	10,806	7,225
Amounts netted on the Consolidated balance sheets	(10,770)	(7,170)
Net derivative receivables	36	55
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	10,062	6,801
Amounts netted on the Consolidated balance sheets	(10,056)	(6,784)
Net derivative payables	6	17
Foreign exchange contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	185,139	157,126
Amounts netted on the Consolidated balance sheets	(171,841)	(144,081)
Net derivative receivables	13,298	13,045
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	188,884	160,231
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	17,043	16,151
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	174,093	152,619
Amounts netted on the Consolidated balance sheets	(165,217)	(143,349)
Net derivative payables	8,876	9,270
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	177,619	155,822
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	12,402	12,473
Foreign exchange contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	184,421	155,289
Amounts netted on the Consolidated balance sheets	(171,163)	(142,420)
Net derivative receivables	13,258	12,869
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	173,389	150,966
Amounts netted on the Consolidated balance sheets	(164,557)	(141,789)
Net derivative payables	8,832	9,177
Foreign exchange contracts | OTC–cleared
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	676	1,696
Amounts netted on the Consolidated balance sheets	(659)	(1,654)
Net derivative receivables	17	42
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	679	1,555
Amounts netted on the Consolidated balance sheets	(654)	(1,553)
Net derivative payables	25	2
Foreign exchange contracts | Exchange-traded
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	42	141
Amounts netted on the Consolidated balance sheets	(19)	(7)
Net derivative receivables	23	134
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	25	98
Amounts netted on the Consolidated balance sheets	(6)	(7)
Net derivative payables	19	91
Equity contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	41,986	36,212
Amounts netted on the Consolidated balance sheets	(36,828)	(32,158)
Net derivative receivables	5,158	4,054
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	46,932	40,040
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	10,104	7,882
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	44,852	40,913
Amounts netted on the Consolidated balance sheets	(39,377)	(36,203)
Net derivative payables	5,475	4,710
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	51,355	45,395
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	11,978	9,192
Equity contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	25,197	22,024
Amounts netted on the Consolidated balance sheets	(22,380)	(19,917)
Net derivative receivables	2,817	2,107
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	28,618	28,193
Amounts netted on the Consolidated balance sheets	(24,869)	(23,969)
Net derivative payables	3,749	4,224
Equity contracts | Exchange-traded
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	16,789	14,188
Amounts netted on the Consolidated balance sheets	(14,448)	(12,241)
Net derivative receivables	2,341	1,947
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	16,234	12,720
Amounts netted on the Consolidated balance sheets	(14,508)	(12,234)
Net derivative payables	1,726	486
Commodity contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	21,695	19,757
Amounts netted on the Consolidated balance sheets	(13,432)	(13,137)
Net derivative receivables	8,263	6,620
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	22,368	20,085
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	8,936	6,948
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	22,165	21,515
Amounts netted on the Consolidated balance sheets	(14,069)	(14,217)
Net derivative payables	8,096	7,298
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	22,839	21,901
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	8,770	7,684
Commodity contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	12,497	10,903
Amounts netted on the Consolidated balance sheets	(4,916)	(4,436)
Net derivative receivables	7,581	6,467
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	13,607	12,645
Amounts netted on the Consolidated balance sheets	(5,600)	(5,508)
Net derivative payables	8,007	7,137
Commodity contracts | Exchange-traded
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	9,198	8,854
Amounts netted on the Consolidated balance sheets	(8,516)	(8,701)
Net derivative receivables	682	153
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	8,558	8,870
Amounts netted on the Consolidated balance sheets	(8,469)	(8,709)
Net derivative payables	$ 89	$ 161