Derivative Instruments and Hedging Activities (Derivative Notionals) (Details) - USD ($) $ in Billions	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Notional Amount
Derivative assets	$ 18,964	$ 16,460
Derivative liabilities	16,603	15,100
Bilateral OTC
Derivatives, Notional Amount
Derivative assets	7,358	6,660
Derivative liabilities	7,491	6,907
Cleared OTC
Derivatives, Notional Amount
Derivative assets	7,677	6,671
Derivative liabilities	7,390	6,587
Exchange Traded
Derivatives, Notional Amount
Derivative assets	3,929	3,129
Derivative liabilities	1,722	1,606
Designated as Accounting Hedges
Derivatives, Notional Amount
Derivative assets	51	70
Derivative liabilities	141	110
Designated as Accounting Hedges | Interest Rate Contracts
Derivatives, Notional Amount
Derivative assets	46	66
Derivative liabilities	135	104
Designated as Accounting Hedges | Foreign Exchange Contracts
Derivatives, Notional Amount
Derivative assets	5	4
Derivative liabilities	6	6
Designated as Accounting Hedges | Bilateral OTC
Derivatives, Notional Amount
Derivative assets	25	24
Derivative liabilities	6	6
Designated as Accounting Hedges | Bilateral OTC | Interest Rate Contracts
Derivatives, Notional Amount
Derivative assets	20	20
Derivative liabilities	2	2
Designated as Accounting Hedges | Bilateral OTC | Foreign Exchange Contracts
Derivatives, Notional Amount
Derivative assets	5	4
Derivative liabilities	4	4
Designated as Accounting Hedges | Cleared OTC
Derivatives, Notional Amount
Derivative assets	26	46
Derivative liabilities	135	104
Designated as Accounting Hedges | Cleared OTC | Interest Rate Contracts
Derivatives, Notional Amount
Derivative assets	26	46
Derivative liabilities	133	102
Designated as Accounting Hedges | Cleared OTC | Foreign Exchange Contracts
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	2	2
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 Contracts
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Designated as Accounting Hedges | Exchange Traded | Foreign Exchange Contracts
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Not Designated as Accounting Hedges
Derivatives, Notional Amount
Derivative assets	18,913	16,390
Derivative liabilities	16,462	14,990
Not Designated as Accounting Hedges | Interest Rate Contracts
Derivatives, Notional Amount
Derivative assets	15,398	13,171
Derivative liabilities	12,869	11,613
Not Designated as Accounting Hedges | Credit Contracts
Derivatives, Notional Amount
Derivative assets	255	294
Derivative liabilities	271	306
Not Designated as Accounting Hedges | Foreign Exchange Contracts
Derivatives, Notional Amount
Derivative assets	2,320	2,036
Derivative liabilities	2,296	2,143
Not Designated as Accounting Hedges | Equity Contracts
Derivatives, Notional Amount
Derivative assets	785	731
Derivative liabilities	899	799
Not Designated as Accounting Hedges | Commodity and Other Contracts
Derivatives, Notional Amount
Derivative assets	155	158
Derivative liabilities	127	129
Not Designated as Accounting Hedges | Bilateral OTC
Derivatives, Notional Amount
Derivative assets	7,333	6,636
Derivative liabilities	7,485	6,901
Not Designated as Accounting Hedges | Bilateral OTC | Interest Rate Contracts
Derivatives, Notional Amount
Derivative assets	4,449	3,999
Derivative liabilities	4,614	4,199
Not Designated as Accounting Hedges | Bilateral OTC | Credit Contracts
Derivatives, Notional Amount
Derivative assets	165	194
Derivative liabilities	188	226
Not Designated as Accounting Hedges | Bilateral OTC | Foreign Exchange Contracts
Derivatives, Notional Amount
Derivative assets	2,223	1,960
Derivative liabilities	2,184	2,014
Not Designated as Accounting Hedges | Bilateral OTC | Equity Contracts
Derivatives, Notional Amount
Derivative assets	402	397
Derivative liabilities	425	394
Not Designated as Accounting Hedges | Bilateral OTC | Commodity and Other Contracts
Derivatives, Notional Amount
Derivative assets	94	86
Derivative liabilities	74	68
Not Designated as Accounting Hedges | Cleared OTC
Derivatives, Notional Amount
Derivative assets	7,651	6,625
Derivative liabilities	7,255	6,483
Not Designated as Accounting Hedges | Cleared OTC | Interest Rate Contracts
Derivatives, Notional Amount
Derivative assets	7,472	6,458
Derivative liabilities	7,074	6,325
Not Designated as Accounting Hedges | Cleared OTC | Credit Contracts
Derivatives, Notional Amount
Derivative assets	90	100
Derivative liabilities	83	80
Not Designated as Accounting Hedges | Cleared OTC | Foreign Exchange Contracts
Derivatives, Notional Amount
Derivative assets	89	67
Derivative liabilities	98	78
Not Designated as Accounting Hedges | Cleared OTC | Equity Contracts
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Not Designated as Accounting Hedges | Cleared OTC | Commodity and Other Contracts
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Not Designated as Accounting Hedges | Exchange Traded
Derivatives, Notional Amount
Derivative assets	3,929	3,129
Derivative liabilities	1,722	1,606
Not Designated as Accounting Hedges | Exchange Traded | Interest Rate Contracts
Derivatives, Notional Amount
Derivative assets	3,477	2,714
Derivative liabilities	1,181	1,089
Not Designated as Accounting Hedges | Exchange Traded | Credit Contracts
Derivatives, Notional Amount
Derivative assets	0	0
Derivative liabilities	0	0
Not Designated as Accounting Hedges | Exchange Traded | Foreign Exchange Contracts
Derivatives, Notional Amount
Derivative assets	8	9
Derivative liabilities	14	51
Not Designated as Accounting Hedges | Exchange Traded | Equity Contracts
Derivatives, Notional Amount
Derivative assets	383	334
Derivative liabilities	474	405
Not Designated as Accounting Hedges | Exchange Traded | Commodity and Other Contracts
Derivatives, Notional Amount
Derivative assets	61	72
Derivative liabilities	$ 53	$ 61