Derivative Instruments - Derivatives Netting (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	$ 552,213	$ 547,995
Amounts netted on the Consolidated balance sheets	(506,740)	(503,030)
Net derivative receivables	45,473	44,965
Derivative receivables where an appropriate legal opinion has not been either sought or obtained	13,037	11,558
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	565,250	559,553
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	58,510	56,523
Collateral not nettable on the Consolidated balance sheets	(13,572)	(13,363)
Net amounts	44,938	43,160
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	521,999	521,133
Amounts netted on the Consolidated balance sheets	(491,351)	(493,029)
Net derivative payables	30,648	28,104
Derivative payables where an appropriate legal opinion has not been either sought or obtained	11,863	9,673
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	533,862	530,806
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	42,511	37,777
Collateral not nettable on the Consolidated balance sheets	(4,363)	(4,180)
Net amounts	38,148	33,597
Net cash collateral receivables	57,300	55,500
Net cash collateral payables	41,900	45,500
Interest rate contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	277,559	312,285
Amounts netted on the Consolidated balance sheets	(258,040)	(291,319)
Net derivative receivables	19,519	20,966
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	281,011	315,992
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	22,971	24,673
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	251,793	283,091
Amounts netted on the Consolidated balance sheets	(245,368)	(277,306)
Net derivative payables	6,425	5,785
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	253,983	284,436
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	8,615	7,129
Interest rate contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	269,291	305,569
Amounts netted on the Consolidated balance sheets	(249,903)	(284,917)
Net derivative receivables	19,388	20,652
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	244,282	276,960
Amounts netted on the Consolidated balance sheets	(237,947)	(271,294)
Net derivative payables	6,335	5,666
Interest rate contracts | OTC–cleared
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	7,958	6,531
Amounts netted on the Consolidated balance sheets	(7,936)	(6,318)
Net derivative receivables	22	213
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	7,301	6,004
Amounts netted on the Consolidated balance sheets	(7,220)	(5,928)
Net derivative payables	81	76
Interest rate contracts | Exchange-traded
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	310	185
Amounts netted on the Consolidated balance sheets	(201)	(84)
Net derivative receivables	109	101
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	210	127
Amounts netted on the Consolidated balance sheets	(201)	(84)
Net derivative payables	9	43
Credit contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	20,725	22,615
Amounts netted on the Consolidated balance sheets	(20,310)	(22,335)
Net derivative receivables	415	280
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	20,934	23,205
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	624	869
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	20,675	22,995
Amounts netted on the Consolidated balance sheets	(19,276)	(21,954)
Net derivative payables	1,399	1,041
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	20,778	23,252
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	1,502	1,299
Credit contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	12,588	15,390
Amounts netted on the Consolidated balance sheets	(12,244)	(15,165)
Net derivative receivables	344	225
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	13,255	16,194
Amounts netted on the Consolidated balance sheets	(11,898)	(15,170)
Net derivative payables	1,357	1,024
Credit contracts | OTC–cleared
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	8,137	7,225
Amounts netted on the Consolidated balance sheets	(8,066)	(7,170)
Net derivative receivables	71	55
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	7,420	6,801
Amounts netted on the Consolidated balance sheets	(7,378)	(6,784)
Net derivative payables	42	17
Foreign exchange contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	192,544	157,126
Amounts netted on the Consolidated balance sheets	(179,709)	(144,081)
Net derivative receivables	12,835	13,045
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	196,472	160,231
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	16,763	16,151
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	184,424	152,619
Amounts netted on the Consolidated balance sheets	(175,046)	(143,349)
Net derivative payables	9,378	9,270
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	187,567	155,822
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	12,521	12,473
Foreign exchange contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	192,088	155,289
Amounts netted on the Consolidated balance sheets	(179,280)	(142,420)
Net derivative receivables	12,808	12,869
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	183,951	150,966
Amounts netted on the Consolidated balance sheets	(174,600)	(141,789)
Net derivative payables	9,351	9,177
Foreign exchange contracts | OTC–cleared
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	417	1,696
Amounts netted on the Consolidated balance sheets	(408)	(1,654)
Net derivative receivables	9	42
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	450	1,555
Amounts netted on the Consolidated balance sheets	(439)	(1,553)
Net derivative payables	11	2
Foreign exchange contracts | Exchange-traded
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	39	141
Amounts netted on the Consolidated balance sheets	(21)	(7)
Net derivative receivables	18	134
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	23	98
Amounts netted on the Consolidated balance sheets	(7)	(7)
Net derivative payables	16	91
Equity contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	40,136	36,212
Amounts netted on the Consolidated balance sheets	(34,789)	(32,158)
Net derivative receivables	5,347	4,054
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	44,965	40,040
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	10,176	7,882
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	42,490	40,913
Amounts netted on the Consolidated balance sheets	(36,902)	(36,203)
Net derivative payables	5,588	4,710
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	48,384	45,395
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	11,482	9,192
Equity contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	24,300	22,024
Amounts netted on the Consolidated balance sheets	(21,376)	(19,917)
Net derivative receivables	2,924	2,107
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	28,247	28,193
Amounts netted on the Consolidated balance sheets	(23,402)	(23,969)
Net derivative payables	4,845	4,224
Equity contracts | Exchange-traded
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	15,836	14,188
Amounts netted on the Consolidated balance sheets	(13,413)	(12,241)
Net derivative receivables	2,423	1,947
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	14,243	12,720
Amounts netted on the Consolidated balance sheets	(13,500)	(12,234)
Net derivative payables	743	486
Commodity contracts
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	21,249	19,757
Amounts netted on the Consolidated balance sheets	(13,892)	(13,137)
Net derivative receivables	7,357	6,620
Total derivative receivables recognized on the Consolidated balance sheets, Gross derivative receivables	21,868	20,085
Total derivative receivables recognized on the Consolidated balance sheets, Net derivative receivables	7,976	6,948
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	22,617	21,515
Amounts netted on the Consolidated balance sheets	(14,759)	(14,217)
Net derivative payables	7,858	7,298
Total derivative payables recognized on the Consolidated balance sheets, Gross derivative payables	23,150	21,901
Total derivative payables recognized on the Consolidated balance sheets, Net derivative payables	8,391	7,684
Commodity contracts | Over-the-counter (“OTC”)
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	11,443	10,903
Amounts netted on the Consolidated balance sheets	(4,553)	(4,436)
Net derivative receivables	6,890	6,467
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	13,215	12,645
Amounts netted on the Consolidated balance sheets	(5,492)	(5,508)
Net derivative payables	7,723	7,137
Commodity contracts | Exchange-traded
Gross and Net Derivative Receivables by Contract and Settlement Type:
Gross derivative receivables	9,806	8,854
Amounts netted on the Consolidated balance sheets	(9,339)	(8,701)
Net derivative receivables	467	153
Gross and Net Derivative Payables by Contract and Settlement Type:
Gross derivative payables	9,402	8,870
Amounts netted on the Consolidated balance sheets	(9,267)	(8,709)
Net derivative payables	$ 135	$ 161