Derivatives and Hedging Activities - Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Notional Amount	$ 105,442	$ 100,193
Derivative assets, netting adjustments	(162)	(443)
Derivative Assets, net	747	664
Derivative liabilities, netting adjustments	(582)	(616)
Derivative Liabilities, net	393	207
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	27,699	26,478
Derivative Assets	40	82
Derivative Liabilities	(3)	50
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	77,743	73,715
Derivative Assets	870	1,030
Derivative Liabilities	1,028	857
Interest Rate [Member] \| Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	27,445	26,176
Derivative Assets	38	81
Derivative Liabilities	(4)	46
Interest Rate [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	65,617	61,390
Derivative Assets	272	641
Derivative Liabilities	449	474
Foreign Exchange [Member] \| Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	254	302
Derivative Assets	2	1
Derivative Liabilities	1	4
Foreign Exchange [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	7,695	8,317
Derivative Assets	100	129
Derivative Liabilities	92	120
Commodity [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,235	1,687
Derivative Assets	491	255
Derivative Liabilities	481	246
Credit [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	401	315
Derivative Assets	0	1
Derivative Liabilities	3	4
Other [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,795	2,006
Derivative Assets	7	4
Derivative Liabilities	3	13
Net Derivatives [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	105,442	100,193
Derivative Assets, net	748	669
Derivative Liabilities, net	443	291
Counterparty And Cash Collateral Netting [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	0	0
Derivative Assets, net	(1)	(5)
Derivative Liabilities, net	$ (50)	$ (84)

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
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-Section 13
-Sentence Column B

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