Derivative Instruments and Hedging Activities - Notionals of Derivative Contracts (Details) - USD ($) $ in Billions	Sep. 30, 2019	Dec. 31, 2018
Derivatives, Notional Amount
Derivative assets	$ 18,245	$ 16,457
Derivative liabilities	18,010	15,522
Bilateral OTC
Derivatives, Notional Amount
Derivative assets	8,158	7,895
Derivative liabilities	8,210	8,027
Cleared OTC
Derivatives, Notional Amount
Derivative assets	8,711	6,953
Derivative liabilities	8,432	6,030
Exchange- Traded
Derivatives, Notional Amount
Derivative assets	1,376	1,609
Derivative liabilities	1,368	1,465
Designated as accounting hedges
Derivatives, Notional Amount
Derivative assets	159	73
Derivative liabilities	24	115
Designated as accounting hedges | Interest rate
Derivatives, Notional Amount
Derivative assets	153	67
Derivative liabilities	17	109
Designated as accounting hedges | Foreign exchange
Derivatives, Notional Amount
Derivative assets	6	6
Derivative liabilities	7	6
Designated as accounting hedges | Bilateral OTC
Derivatives, Notional Amount
Derivative assets	16	20
Derivative liabilities	5	7
Designated as accounting hedges | Bilateral OTC | Interest rate
Derivatives, Notional Amount
Derivative assets	11	15
Derivative liabilities	0	2
Designated as accounting hedges | Bilateral OTC | Foreign exchange
Derivatives, Notional Amount
Derivative assets	5	5
Derivative liabilities	5	5
Designated as accounting hedges | Cleared OTC
Derivatives, Notional Amount
Derivative assets	143	53
Derivative liabilities	19	108
Designated as accounting hedges | Cleared OTC | Interest rate
Derivatives, Notional Amount
Derivative assets	142	52
Derivative liabilities	17	107
Designated as accounting hedges | Cleared OTC | Foreign exchange
Derivatives, Notional Amount
Derivative assets	1	1
Derivative liabilities	2	1
Designated as accounting hedges | Exchange- Traded
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Designated as accounting hedges | Exchange- Traded | Interest rate
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Designated as accounting hedges | Exchange- Traded | Foreign exchange
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Not designated as accounting hedges
Derivatives, Notional Amount
Derivative assets	18,086	16,384
Derivative liabilities	17,986	15,407
Not designated as accounting hedges | Interest rate
Derivatives, Notional Amount
Derivative assets	13,680	12,672
Derivative liabilities	13,445	11,462
Not designated as accounting hedges | Credit
Derivatives, Notional Amount
Derivative assets	230	236
Derivative liabilities	254	235
Not designated as accounting hedges | Foreign exchange
Derivatives, Notional Amount
Derivative assets	3,166	2,568
Derivative liabilities	3,119	2,582
Not designated as accounting hedges | Equity
Derivatives, Notional Amount
Derivative assets	836	744
Derivative liabilities	1,018	991
Not designated as accounting hedges | Commodity and other
Derivatives, Notional Amount
Derivative assets	174	164
Derivative liabilities	150	137
Not designated as accounting hedges | Bilateral OTC
Derivatives, Notional Amount
Derivative assets	8,142	7,875
Derivative liabilities	8,205	8,020
Not designated as accounting hedges | Bilateral OTC | Interest rate
Derivatives, Notional Amount
Derivative assets	4,465	4,807
Derivative liabilities	4,462	4,946
Not designated as accounting hedges | Bilateral OTC | Credit
Derivatives, Notional Amount
Derivative assets	138	162
Derivative liabilities	149	162
Not designated as accounting hedges | Bilateral OTC | Foreign exchange
Derivatives, Notional Amount
Derivative assets	3,030	2,436
Derivative liabilities	2,985	2,451
Not designated as accounting hedges | Bilateral OTC | Equity
Derivatives, Notional Amount
Derivative assets	404	373
Derivative liabilities	525	389
Not designated as accounting hedges | Bilateral OTC | Commodity and other
Derivatives, Notional Amount
Derivative assets	105	97
Derivative liabilities	84	72
Not designated as accounting hedges | Cleared OTC
Derivatives, Notional Amount
Derivative assets	8,568	6,900
Derivative liabilities	8,413	5,922
Not designated as accounting hedges | Cleared OTC | Interest rate
Derivatives, Notional Amount
Derivative assets	8,357	6,708
Derivative liabilities	8,189	5,735
Not designated as accounting hedges | Cleared OTC | Credit
Derivatives, Notional Amount
Derivative assets	92	74
Derivative liabilities	105	73
Not designated as accounting hedges | Cleared OTC | Foreign exchange
Derivatives, Notional Amount
Derivative assets	119	118
Derivative liabilities	119	114
Not designated as accounting hedges | Cleared OTC | Equity
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Not designated as accounting hedges | Cleared OTC | Commodity and other
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Not designated as accounting hedges | Exchange- Traded
Derivatives, Notional Amount
Derivative assets	1,376	1,609
Derivative liabilities	1,368	1,465
Not designated as accounting hedges | Exchange- Traded | Interest rate
Derivatives, Notional Amount
Derivative assets	858	1,157
Derivative liabilities	794	781
Not designated as accounting hedges | Exchange- Traded | Credit
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Not designated as accounting hedges | Exchange- Traded | Foreign exchange
Derivatives, Notional Amount
Derivative assets	17	14
Derivative liabilities	15	17
Not designated as accounting hedges | Exchange- Traded | Equity
Derivatives, Notional Amount
Derivative assets	432	371
Derivative liabilities	493	602
Not designated as accounting hedges | Exchange- Traded | Commodity and other
Derivatives, Notional Amount
Derivative assets	69	67
Derivative liabilities	$ 66	$ 65