Derivative Instruments - Impact on Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Gross derivative receivables	$ 565,250	$ 559,553
Net derivative receivables	58,510	56,523
Gross derivative payables	533,862	530,806
Net derivative payables	42,511	37,777
Interest rate
Derivatives, Fair Value [Line Items]
Gross derivative receivables	281,011	315,992
Net derivative receivables	22,971	24,673
Gross derivative payables	253,983	284,436
Net derivative payables	8,615	7,129
Credit
Derivatives, Fair Value [Line Items]
Gross derivative receivables	20,934	23,205
Net derivative receivables	624	869
Gross derivative payables	20,778	23,252
Net derivative payables	1,502	1,299
Foreign exchange
Derivatives, Fair Value [Line Items]
Gross derivative receivables	196,472	160,231
Net derivative receivables	16,763	16,151
Gross derivative payables	187,567	155,822
Net derivative payables	12,521	12,473
Equity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	44,965	40,040
Net derivative receivables	10,176	7,882
Gross derivative payables	48,384	45,395
Net derivative payables	11,482	9,192
Commodity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	21,868	20,085
Net derivative receivables	7,976	6,948
Gross derivative payables	23,150	21,901
Net derivative payables	8,391	7,684
Not designated as hedges
Derivatives, Fair Value [Line Items]
Gross derivative receivables	563,148	558,013
Gross derivative payables	532,680	529,179
Not designated as hedges | Interest rate
Derivatives, Fair Value [Line Items]
Gross derivative receivables	280,176	314,962
Gross derivative payables	253,982	284,433
Not designated as hedges | Credit
Derivatives, Fair Value [Line Items]
Gross derivative receivables	20,934	23,205
Gross derivative payables	20,778	23,252
Not designated as hedges | Foreign exchange
Derivatives, Fair Value [Line Items]
Gross derivative receivables	195,436	159,740
Gross derivative payables	186,487	154,601
Not designated as hedges | Equity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	44,965	40,040
Gross derivative payables	48,384	45,395
Not designated as hedges | Commodity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	21,637	20,066
Gross derivative payables	23,049	21,498
Designated as hedges
Derivatives, Fair Value [Line Items]
Gross derivative receivables	2,102	1,540
Gross derivative payables	1,182	1,627
Designated as hedges | Interest rate
Derivatives, Fair Value [Line Items]
Gross derivative receivables	835	1,030
Gross derivative payables	1	3
Designated as hedges | Credit
Derivatives, Fair Value [Line Items]
Gross derivative receivables	0	0
Gross derivative payables	0	0
Designated as hedges | Foreign exchange
Derivatives, Fair Value [Line Items]
Gross derivative receivables	1,036	491
Gross derivative payables	1,080	1,221
Designated as hedges | Equity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	0	0
Gross derivative payables	0	0
Designated as hedges | Commodity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	231	19
Gross derivative payables	$ 101	$ 403