Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 673	$ 2,978
Less than 12 months, unrealized losses	(13)	(128)
12 months or longer, fair value	1,551	479
12 months or longer, unrealized losses	(77)	(101)
Total available-for-sale, fair value	2,224	3,457
Total available-for-sale, unrealized losses	(90)	(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	445	1,244
12 months or longer, unrealized losses	(130)	(181)
Total held-to-maturity, fair value	445	1,244
Total held-to-maturity, unrealized losses	(130)	(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	445	1,244
12 months or longer, unrealized losses	(130)	(181)
Total held-to-maturity, fair value	445	1,244
Total held-to-maturity, unrealized losses	(130)	(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	0	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	0	5
Total available-for-sale, unrealized losses	0	0
Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	673	2,973
Less than 12 months, unrealized losses	(13)	(128)
12 months or longer, fair value	1,551	479
12 months or longer, unrealized losses	(77)	(101)
Total available-for-sale, fair value	2,224	3,452
Total available-for-sale, unrealized losses	(90)	(229)
Fixed Maturities [Member] | U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	98	269
Less than 12 months, unrealized losses	0	(9)
12 months or longer, fair value	176	1
12 months or longer, unrealized losses	(4)	0
Total available-for-sale, fair value	274	270
Total available-for-sale, unrealized losses	(4)	(9)
Fixed Maturities [Member] | US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	29	1,112
Less than 12 months, unrealized losses	0	(65)
12 months or longer, fair value	477	49
12 months or longer, unrealized losses	(16)	(8)
Total available-for-sale, fair value	506	1,161
Total available-for-sale, unrealized losses	(16)	(73)
Fixed Maturities [Member] | Foreign Government Debt [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	150	36
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	150	36
Total available-for-sale, unrealized losses	(1)	0
Fixed Maturities [Member] | Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	341	788
Less than 12 months, unrealized losses	(12)	(30)
12 months or longer, fair value	293	82
12 months or longer, unrealized losses	(9)	(8)
Total available-for-sale, fair value	634	870
Total available-for-sale, unrealized losses	(21)	(38)
Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	18	713
Less than 12 months, unrealized losses	0	(23)
12 months or longer, fair value	440	144
12 months or longer, unrealized losses	(12)	(8)
Total available-for-sale, fair value	458	857
Total available-for-sale, unrealized losses	(12)	(31)
Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	2	17
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	21	22
12 months or longer, unrealized losses	(4)	(5)
Total available-for-sale, fair value	23	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	8	11
Less than 12 months, unrealized losses	0	(1)
12 months or longer, fair value	7	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	15	11
Total available-for-sale, unrealized losses	0	(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	89	124
12 months or longer, unrealized losses	(23)	(57)
Total available-for-sale, fair value	91	130
Total available-for-sale, unrealized losses	(23)	(57)
Fixed Maturities [Member] | Other Asset Backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	25	21
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	48	57
12 months or longer, unrealized losses	(9)	(15)
Total available-for-sale, fair value	73	78
Total available-for-sale, unrealized losses	$ (9)	$ (15)