Derivative Instruments - Customer-Related Derivative Positions of Company (Detail) - Customer-Related Positions [Member] - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Notional Value, Assets	$ 67,963	$ 50,780
Fair Value, Assets	2,040	1,853
Notional Value, Liabilities	63,224	47,993
Fair Value, Liabilities	1,982	1,717
Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	28,676	21,724
Fair Value, Assets	$ 895	$ 888
Derivative Asset Average Remaining Maturity Period	4 years 9 months 7 days	6 years 1 month 2 days
Notional Value, Liabilities	$ 7,701	$ 5,880
Fair Value, Liabilities	$ 93	$ 24
Derivative Liability Average Remaining Maturity Period	7 years 11 months 1 day	3 years 9 months 15 days
Interest Rate Contracts [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	$ 7,214	$ 4,622
Fair Value, Assets	$ 79	$ 26
Derivative Asset Average Remaining Maturity Period	6 years 10 months 10 days	3 years 3 months 7 days
Notional Value, Liabilities	$ 27,938	$ 21,821
Fair Value, Liabilities	$ 915	$ 892
Derivative Liability Average Remaining Maturity Period	5 years 22 days	6 years 29 days
Interest Rate Contracts [Member] | Options [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 7,989	$ 4,409
Fair Value, Assets	$ 16	$ 10
Derivative Asset Average Remaining Maturity Period	3 years 2 months 19 days	3 years 9 months 15 days
Notional Value, Liabilities	$ 23	$ 24
Derivative Liability Average Remaining Maturity Period	1 year 11 months 1 day	2 years 5 months 1 day
Interest Rate Contracts [Member] | Options [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Assets	$ 23	$ 24
Derivative Asset Average Remaining Maturity Period	1 year 11 months 1 day	2 years 5 months 1 day
Notional Value, Liabilities	$ 7,756	$ 4,375
Fair Value, Liabilities	$ 14	$ 10
Derivative Liability Average Remaining Maturity Period	3 years 2 months 1 day	3 years 9 months 15 days
Interest Rate Contracts [Member] | Futures [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 4,079	$ 1,811
Fair Value, Assets	$ 1
Derivative Asset Average Remaining Maturity Period	11 months 5 days	2 months 19 days
Notional Value, Liabilities		$ 226
Derivative Liability Average Remaining Maturity Period		5 months 12 days
Interest Rate Contracts [Member] | Futures [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Assets		$ 152
Derivative Asset Average Remaining Maturity Period		1 year 29 days
Notional Value, Liabilities		$ 46
Derivative Liability Average Remaining Maturity Period		1 year 8 months 23 days
Foreign Exchange Rate Contracts [Member] | Forwards, Spots and Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	$ 18,466	$ 17,062
Fair Value, Assets	$ 983	$ 890
Derivative Asset Average Remaining Maturity Period	7 months 21 days	6 months 7 days
Notional Value, Liabilities	$ 18,290	$ 14,645
Fair Value, Liabilities	$ 894	$ 752
Derivative Liability Average Remaining Maturity Period	7 months 13 days	7 months 2 days
Foreign Exchange Option [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 1,516	$ 976
Fair Value, Assets	$ 66	$ 39
Derivative Asset Average Remaining Maturity Period	1 year 1 month 10 days	5 months 9 days
Foreign Exchange Option [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Liabilities	$ 1,516	$ 976
Fair Value, Liabilities	$ 66	$ 39
Derivative Liability Average Remaining Maturity Period	1 year 1 month 10 days	5 months 9 days