Derivative Instruments - Asset and Liability Management Derivative Positions of Company (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Derivative [Line Items]
Fair Value, Assets	$ 1,167	$ 1,349
Fair Value, Liabilities	1,432	1,598
Asset and Liability Management Positions [Member]
Derivative [Line Items]
Notional Value, Assets	27,445	28,119
Fair Value, Assets	214	189
Notional Value, Liabilities	15,939	14,730
Fair Value, Liabilities	546	580
Asset and Liability Management Positions [Member] | 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	32	22
Derivative Asset Average Remaining Maturity Period	3 years 10 months 24 days	2 years 1 month 2 days
Notional Value, Liabilities
Fair Value, Liabilities
Derivative Liability Average Remaining Maturity Period
Asset and Liability Management Positions [Member] | Cash Flow Hedges [Member] | Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	7,000	7,000
Fair Value, Assets	14	26
Derivative Asset Average Remaining Maturity Period	4 months 6 days	10 months 2 days
Notional Value, Liabilities
Fair Value, Liabilities
Derivative Liability Average Remaining Maturity Period
Asset and Liability Management Positions [Member] | Cash Flow Hedges [Member] | Interest Rate Contracts [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	272	772
Fair Value, Assets	12	26
Derivative Asset Average Remaining Maturity Period	8 years 3 months 7 days	6 years 3 months
Notional Value, Liabilities	5,371	4,288
Fair Value, Liabilities	415	498
Derivative Liability Average Remaining Maturity Period	2 years 3 months 26 days	2 years 5 months 16 days
Asset and Liability Management Positions [Member] | Net Investment Hedges [Member] | Foreign Exchange Forward Contracts [Member]
Derivative [Line Items]
Notional Value, Assets
Fair Value, Assets
Derivative Asset Average Remaining Maturity Period
Notional Value, Liabilities	1,069	1,056
Fair Value, Liabilities	7	4
Derivative Liability Average Remaining Maturity Period	18 days	15 days
Asset and Liability Management Positions [Member] | Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	3,520
Fair Value, Assets	49
Derivative Asset Average Remaining Maturity Period	10 years 2 months 23 days
Notional Value, Liabilities		3,540
Fair Value, Liabilities		56
Derivative Liability Average Remaining Maturity Period		10 years 2 months 19 days
Asset and Liability Management Positions [Member] | Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Futures and Forwards [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	4,813	2,310
Fair Value, Assets	49	9
Derivative Asset Average Remaining Maturity Period	29 days	26 days
Notional Value, Liabilities	62	1,025
Fair Value, Liabilities		7
Derivative Liability Average Remaining Maturity Period	1 month 2 days	22 days
Asset and Liability Management Positions [Member] | Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Futures and Forwards [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Assets	404	5,234
Fair Value, Assets	3	58
Derivative Asset Average Remaining Maturity Period	1 month 10 days	29 days
Notional Value, Liabilities	5,583	346
Fair Value, Liabilities	64	4
Derivative Liability Average Remaining Maturity Period	1 month 6 days	2 months 1 day
Asset and Liability Management Positions [Member] | Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Options [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	2,320	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
Asset and Liability Management Positions [Member] | Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Options [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Assets	2,135	1,902
Fair Value, Assets	38	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	1 month 2 days	29 days
Asset and Liability Management Positions [Member] | Other Economic Hedges [Member] | Foreign Exchange Forward Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	3,848	6,813
Fair Value, Assets	12	24
Derivative Asset Average Remaining Maturity Period	4 days	7 days
Notional Value, Liabilities	1,334	2,121
Fair Value, Liabilities	10	4
Derivative Liability Average Remaining Maturity Period	11 days	7 days
Asset and Liability Management Positions [Member] | Other Economic Hedges [Member] | Equity Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	80	79
Fair Value, Assets	1	3
Derivative Asset Average Remaining Maturity Period	1 year 1 month 10 days	1 year 7 months 13 days
Notional Value, Liabilities
Fair Value, Liabilities
Derivative Liability Average Remaining Maturity Period
Asset and Liability Management Positions [Member] | Other Economic Hedges [Member] | Credit Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	1,303	1,209
Fair Value, Assets	4	4
Derivative Asset Average Remaining Maturity Period	3 years 7 months 2 days	4 years 15 days
Notional Value, Liabilities	2,247	2,352
Fair Value, Liabilities	6	7
Derivative Liability Average Remaining Maturity Period	3 years 2 months 19 days	3 years 29 days
Asset and Liability Management Positions [Member] | Other Derivatives [Member]
Derivative [Line Items]
Notional Value, Assets
Fair Value, Assets
Derivative Asset Average Remaining Maturity Period
Notional Value, Liabilities	265
Fair Value, Liabilities	$ 43
Derivative Liability Average Remaining Maturity Period	4 years 3 months 4 days