Derivative Instruments - Impact on Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Gross derivative receivables	$ 543,148	$ 559,553
Net derivative receivables	60,062	56,523
Gross derivative payables	509,406	530,806
Net derivative payables	41,693	37,777
Interest rate
Derivatives, Fair Value [Line Items]
Gross derivative receivables	261,459	315,992
Net derivative receivables	23,397	24,673
Gross derivative payables	234,233	284,436
Net derivative payables	7,091	7,129
Credit
Derivatives, Fair Value [Line Items]
Gross derivative receivables	23,505	23,205
Net derivative receivables	582	869
Gross derivative payables	23,360	23,252
Net derivative payables	1,452	1,299
Foreign exchange
Derivatives, Fair Value [Line Items]
Gross derivative receivables	188,884	160,231
Net derivative receivables	17,043	16,151
Gross derivative payables	177,619	155,822
Net derivative payables	12,402	12,473
Equity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	46,932	40,040
Net derivative receivables	10,104	7,882
Gross derivative payables	51,355	45,395
Net derivative payables	11,978	9,192
Commodity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	22,368	20,085
Net derivative receivables	8,936	6,948
Gross derivative payables	22,839	21,901
Net derivative payables	8,770	7,684
Not designated as hedges
Derivatives, Fair Value [Line Items]
Gross derivative receivables	541,509	558,013
Gross derivative payables	508,467	529,179
Not designated as hedges | Interest rate
Derivatives, Fair Value [Line Items]
Gross derivative receivables	260,636	314,962
Gross derivative payables	234,232	284,433
Not designated as hedges | Credit
Derivatives, Fair Value [Line Items]
Gross derivative receivables	23,505	23,205
Gross derivative payables	23,360	23,252
Not designated as hedges | Foreign exchange
Derivatives, Fair Value [Line Items]
Gross derivative receivables	188,261	159,740
Gross derivative payables	176,771	154,601
Not designated as hedges | Equity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	46,932	40,040
Gross derivative payables	51,355	45,395
Not designated as hedges | Commodity
Derivatives, Fair Value [Line Items]
Gross derivative receivables	22,175	20,066
Gross derivative payables	22,749	21,498
Designated as hedges
Derivatives, Fair Value [Line Items]
Gross derivative receivables	1,639	1,540
Gross derivative payables	939	1,627
Designated as hedges | Interest rate
Derivatives, Fair Value [Line Items]
Gross derivative receivables	823	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	623	491
Gross derivative payables	848	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	193	19
Gross derivative payables	$ 90	$ 403