Derivatives and Hedging Activities - Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Notional Amount	$ 108,651	$ 100,193
Derivative assets, netting adjustments	(219)	(443)
Derivative Assets, net	736	664
Derivative liabilities, netting adjustments	(598)	(616)
Derivative Liabilities, net	357	207
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	29,174	26,478
Derivative Assets	40	82
Derivative Liabilities	2	50
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	79,477	73,715
Derivative Assets	917	1,030
Derivative Liabilities	1,022	857
Interest Rate [Member] \| Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	28,918	26,176
Derivative Assets	37	81
Derivative Liabilities	2	46
Interest Rate [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	66,309	61,390
Derivative Assets	306	641
Derivative Liabilities	421	474
Foreign Exchange [Member] \| Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	256	302
Derivative Assets	3	1
Derivative Liabilities	0	4
Foreign Exchange [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	9,378	8,317
Derivative Assets	113	129
Derivative Liabilities	103	120
Commodity [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,165	1,687
Derivative Assets	494	255
Derivative Liabilities	484	246
Credit [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	381	315
Derivative Assets	0	1
Derivative Liabilities	12	4
Other [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,244	2,006
Derivative Assets	4	4
Derivative Liabilities	2	13
Net Derivatives [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	108,651	100,193
Derivative Assets, net	738	669
Derivative Liabilities, net	426	291
Counterparty And Cash Collateral Netting [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	0	0
Derivative Assets, net	(2)	(5)
Derivative Liabilities, net	$ (69)	$ (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)
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-Section 13
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