Reconciliation of Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance						$ 484		$ 437
Included in earnings						119		90
Sales						(1)
Settlements						(53)		(66)
Transfers Into Level 3	[1]					84		12
Ending Balance		$ 633		$ 473		633		473
The amount of total gains or losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	[3]					81	[2]	33
Quarter to date
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance		568		422
Included in earnings		29		86
Sales		(1)
Settlements		(24)		(35)
Transfers Into Level 3	[1],[4]	61
Ending Balance		633		473		633		473
The amount of total gains or losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	[3]	25	[2]	65
Trading Securities
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance								1
Ending Balance				1				1
Trading Securities | Quarter to date
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance				1
Ending Balance				1				1
Residential Mortgage
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance						108		92
Included in earnings						1		3
Settlements						(15)		(8)
Transfers Into Level 3	[1]					84	[4]	12
Ending Balance		178		99		178		99
The amount of total gains or losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	[3]					1	[2]	3
Residential Mortgage | Quarter to date
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance		126		103
Included in earnings		(1)		1
Settlements		(8)		(5)
Transfers Into Level 3	[1],[4]	61
Ending Balance		178		99		178		99
The amount of total gains or losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	[3]	(1)	[2]	1
Interest Rate Contract
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance						10	[5]	8	[6]
Included in earnings						52	[5]	74	[6]
Sales	[5]					(1)
Settlements						(51)	[5]	(67)	[6]
Ending Balance		10	[5]	15	[6]	10	[5]	15	[6]
The amount of total gains or losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	[3]					14	[2],[5]	17	[6]
Interest Rate Contract | Quarter to date
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance		17	[5]	13	[7]
Included in earnings		17	[5]	37	[7]
Sales	[5]	(1)
Settlements		(23)	[5]	(35)	[7]
Ending Balance		10	[5]	15	[7]	10	[5]	15	[7]
The amount of total gains or losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	[3]	13	[2],[5]	16	[7]
Equity Contract
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance						366	[5]	336	[6]
Included in earnings						66	[5]	13	[6]
Settlements						13	[5]	9	[6]
Ending Balance		445	[5]	358	[6]	445	[5]	358	[6]
The amount of total gains or losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	[3]					66	[2],[5]	13	[6]
Equity Contract | Quarter to date
FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollforward
Beginning Balance		425	[5]	305	[7]
Included in earnings		13	[5]	48	[7]
Settlements		7	[5]	5	[7]
Ending Balance		445	[5]	358	[7]	$ 445	[5]	$ 358	[7]
The amount of total gains or losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held	[3]	$ 13	[2],[5]	$ 48	[7]

[1] Includes certain residential mortgage loans held for sale that were transferred to held for investment.

[2] Includes interest income and expense.

[3] Includes interest income and expense.

[4] Includes certain residential mortgage loans held for sale that were transferred to held for investment.

[5] Net interest rate derivatives include derivative assets and liabilities of $14 and $4, respectively, as of June 30, 2015. Net equity derivatives include derivative assets and liabilities of $500 and $55, respectively, as of June 30, 2015.

[6] Net interest rate derivatives include derivative assets and liabilities of $17 and $2, respectively, as of June 30, 2014. Net equity derivatives include derivative assets and liabilities of $412 and $54, respectively, as of June 30, 2014.

[7] Net interest rate derivatives include derivative assets and liabilities of $17 and $2, respectively, as of June 30, 2014. Net equity derivatives include derivative assets and liabilities of $412 and $54, respectively, as of June 30, 2014.