Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 2,457	$ 2,978
Less than 12 months, unrealized losses	(76)	(128)
12 months or longer, fair value	534	479
12 months or longer, unrealized losses	(91)	(101)
Total available-for-sale, fair value	2,991	3,457
Total available-for-sale, unrealized losses	(167)	(229)
Held To Maturity Securities [Abstract]
Less than 12 months, fair value	0	0
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	420	1,244
12 months or longer, unrealized losses	(155)	(181)
Total held-to-maturity, fair value	420	1,244
Total held-to-maturity, unrealized losses	(155)	(181)
Corporate Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value		0
Less than 12 months, unrealized losses		0
12 months or longer, fair value		0
12 months or longer, unrealized losses		0
Total available-for-sale, fair value		0
Total available-for-sale, unrealized losses		0
Held To Maturity Securities [Abstract]
Less than 12 months, fair value	0	0
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	420	1,244
12 months or longer, unrealized losses	(155)	(181)
Total held-to-maturity, fair value	420	1,244
Total held-to-maturity, unrealized losses	(155)	(181)
Residential Mortgage Backed Non Agency [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value		0
Less than 12 months, unrealized losses		0
12 months or longer, fair value		0
12 months or longer, unrealized losses		0
Total available-for-sale, fair value		0
Total available-for-sale, unrealized losses		0
Collateralized Debt Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value		0
Less than 12 months, unrealized losses		0
12 months or longer, fair value		0
12 months or longer, unrealized losses		0
Total available-for-sale, fair value		0
Total available-for-sale, unrealized losses		0
Other Asset Backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value		0
Less than 12 months, unrealized losses		0
12 months or longer, fair value		0
12 months or longer, unrealized losses		0
Total available-for-sale, fair value		0
Total available-for-sale, unrealized losses		0
Perpetual Debt And Equity Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	2	5
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	2	5
Total available-for-sale, unrealized losses	0	0
Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	2,455	2,973
Less than 12 months, unrealized losses	(76)	(128)
12 months or longer, fair value	534	479
12 months or longer, unrealized losses	(91)	(101)
Total available-for-sale, fair value	2,989	3,452
Total available-for-sale, unrealized losses	(167)	(229)
Fixed Maturities [Member] | U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	261	269
Less than 12 months, unrealized losses	(7)	(9)
12 months or longer, fair value	1	1
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	262	270
Total available-for-sale, unrealized losses	(7)	(9)
Fixed Maturities [Member] | US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	639	1,112
Less than 12 months, unrealized losses	(26)	(65)
12 months or longer, fair value	54	49
12 months or longer, unrealized losses	(6)	(8)
Total available-for-sale, fair value	693	1,161
Total available-for-sale, unrealized losses	(32)	(73)
Fixed Maturities [Member] | Foreign Government Debt [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	110	36
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	110	36
Total available-for-sale, unrealized losses	0	0
Fixed Maturities [Member] | Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	812	788
Less than 12 months, unrealized losses	(29)	(30)
12 months or longer, fair value	85	82
12 months or longer, unrealized losses	(5)	(8)
Total available-for-sale, fair value	897	870
Total available-for-sale, unrealized losses	(34)	(38)
Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	592	713
Less than 12 months, unrealized losses	(13)	(23)
12 months or longer, fair value	193	144
12 months or longer, unrealized losses	(9)	(8)
Total available-for-sale, fair value	785	857
Total available-for-sale, unrealized losses	(22)	(31)
Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	5	17
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	22	22
12 months or longer, unrealized losses	(4)	(5)
Total available-for-sale, fair value	27	39
Total available-for-sale, unrealized losses	(4)	(5)
Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	14	11
Less than 12 months, unrealized losses	(1)	(1)
12 months or longer, fair value	2	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	16	11
Total available-for-sale, unrealized losses	(1)	(1)
Fixed Maturities [Member] | Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	2	6
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	127	124
12 months or longer, unrealized losses	(55)	(57)
Total available-for-sale, fair value	129	130
Total available-for-sale, unrealized losses	(55)	(57)
Fixed Maturities [Member] | Other Asset Backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	20	21
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	50	57
12 months or longer, unrealized losses	(12)	(15)
Total available-for-sale, fair value	70	78
Total available-for-sale, unrealized losses	$ (12)	$ (15)