Derivative Instruments - Asset and Liability Management Derivative Positions of Company (Detail) (Asset and Liability Management Positions [Member], USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Derivative [Line Items]
Notional Value, Assets	$ 26,822	$ 28,119
Fair Value, Assets	168	189
Derivative Asset Average Remaining Maturity Period
Notional Value, Liabilities	17,816	14,730
Fair Value, Liabilities	480	580
Derivative Liability Average Remaining Maturity Period
Fair Value Hedges [Member] | Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	1,750	500
Fair Value, Assets	21	22
Derivative Asset Average Remaining Maturity Period	3 years 7 months 24 days	2 years 1 month 2 days
Notional Value, Liabilities	1,000
Fair Value, Liabilities	4
Derivative Liability Average Remaining Maturity Period	9 years 11 months 16 days
Cash Flow Hedges [Member] | Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	5,500	7,000
Fair Value, Assets	6	26
Derivative Asset Average Remaining Maturity Period	1 month 24 days	10 months 2 days
Notional Value, Liabilities
Fair Value, Liabilities
Derivative Liability Average Remaining Maturity Period
Cash Flow Hedges [Member] | Interest Rate Contracts [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	1,972	772
Fair Value, Assets	15	26
Derivative Asset Average Remaining Maturity Period	3 years 8 months 23 days	6 years 3 months
Notional Value, Liabilities	4,084	4,288
Fair Value, Liabilities	351	498
Derivative Liability Average Remaining Maturity Period	1 year 9 months 22 days	2 years 5 months 16 days
Net Investment Hedges [Member] | Foreign Exchange Forward Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	1,043
Fair Value, Assets	29
Derivative Asset Average Remaining Maturity Period	18 days
Notional Value, Liabilities		1,056
Fair Value, Liabilities		4
Derivative Liability Average Remaining Maturity Period		15 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	3,375
Fair Value, Assets	6
Derivative Asset Average Remaining Maturity Period	10 years 2 months 19 days
Notional Value, Liabilities	232	3,540
Fair Value, Liabilities	3	56
Derivative Liability Average Remaining Maturity Period	10 years 2 months 19 days	10 years 2 months 19 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets
Fair Value, Assets
Derivative Asset Average Remaining Maturity Period
Notional Value, Liabilities	55
Fair Value, Liabilities
Derivative Liability Average Remaining Maturity Period	10 years 2 months 19 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Futures and Forwards [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	2,981	2,310
Fair Value, Assets	20	9
Derivative Asset Average Remaining Maturity Period	1 month 2 days	26 days
Notional Value, Liabilities	1,422	1,025
Fair Value, Liabilities	4	7
Derivative Liability Average Remaining Maturity Period	18 days	22 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Futures and Forwards [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Assets	2,691	5,234
Fair Value, Assets	10	58
Derivative Asset Average Remaining Maturity Period	1 month 6 days	29 days
Notional Value, Liabilities	4,077	346
Fair Value, Liabilities	22	4
Derivative Liability Average Remaining Maturity Period	1 month 10 days	2 months 1 day
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Options [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	2,100	2,300
Fair Value, Assets
Derivative Asset Average Remaining Maturity Period	26 days	26 days
Notional Value, Liabilities
Fair Value, Liabilities
Derivative Liability Average Remaining Maturity Period
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Options [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Assets	2,349	1,902
Fair Value, Assets	32	17
Derivative Asset Average Remaining Maturity Period	29 days	26 days
Notional Value, Liabilities	8	2
Fair Value, Liabilities	1
Derivative Liability Average Remaining Maturity Period	29 days	29 days
Other Economic Hedges [Member] | Foreign Exchange Forward Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	1,049	6,813
Fair Value, Assets	11	24
Derivative Asset Average Remaining Maturity Period	7 days	7 days
Notional Value, Liabilities	3,576	2,121
Fair Value, Liabilities	38	4
Derivative Liability Average Remaining Maturity Period	4 days	7 days
Other Economic Hedges [Member] | Equity Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	27	79
Fair Value, Assets		3
Derivative Asset Average Remaining Maturity Period	1 year 1 month 17 days	1 year 7 months 13 days
Notional Value, Liabilities	57
Fair Value, Liabilities	1
Derivative Liability Average Remaining Maturity Period	8 months 19 days
Other Economic Hedges [Member] | Credit Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	1,263	1,209
Fair Value, Assets	3	4
Derivative Asset Average Remaining Maturity Period	3 years 4 months 24 days	4 years 15 days
Notional Value, Liabilities	2,288	2,352
Fair Value, Liabilities	5	7
Derivative Liability Average Remaining Maturity Period	3 years 15 days	3 years 29 days
Other Derivatives [Member]
Derivative [Line Items]
Notional Value, Assets	722
Fair Value, Assets	15
Derivative Asset Average Remaining Maturity Period	4 days
Notional Value, Liabilities	1,017
Fair Value, Liabilities	$ 51
Derivative Liability Average Remaining Maturity Period	1 year 2 months 1 day