Derivative Instruments (Credit Derivatives Sold) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Derivative notional amount	$ 23,389	$ 31,316
Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	20,952	28,935
Total fair value of credit derivatives	(313)	(1,152)
Insurance Operations [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Weighted average remaining expected maturity	2 years 6 months 0 days	2 years 7 months 6 days
Derivative notional amount	16,682	23,954
Total fair value of credit derivatives	(309)	(1,132)
Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Weighted average remaining expected maturity	17 years 0 months 0 days	18 years 6 months 0 days
Derivative notional amount	4,270	4,945
Total fair value of credit derivatives	(4)	(5)
Insurance Operations [Member] | Other Credit Derivatives [Member]
Derivative [Line Items]
Weighted average remaining expected maturity		28 years 0 months 0 days
Derivative notional amount	0	36
Total fair value of credit derivatives	0	(15)
Credit Rating Aaa [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	7,397	7,406
Total fair value of credit derivatives	(2)	(2)
Credit Rating Aaa [Member] | Insurance Operations [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative notional amount	7,397	7,406
Credit Rating Aaa [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Credit Rating Aaa [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Credit Rating Aa [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	795	2,049
Total fair value of credit derivatives	0	0
Credit Rating Aa [Member] | Insurance Operations [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative notional amount	718	1,972
Credit Rating Aa [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	77	77
Credit Rating Aa [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Credit Rating A [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	4,119	4,350
Total fair value of credit derivatives	(3)	(3)
Credit Rating A [Member] | Insurance Operations [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative notional amount	968	1,068
Credit Rating A [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	3,151	3,282
Credit Rating A [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Credit Rating Bbb [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	5,778	9,138
Total fair value of credit derivatives	(4)	(78)
Credit Rating Bbb [Member] | Insurance Operations [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative notional amount	4,736	7,552
Credit Rating Bbb [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	1,042	1,586
Credit Rating Bbb [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	2,863	5,992
Total fair value of credit derivatives	(304)	(1,069)
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative notional amount	2,863	5,956
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member] | Other Credit Derivatives [Member]
Derivative [Line Items]
Derivative notional amount	$ 0	$ 36