Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Available For Sale Securities [Abstract]
Amortized cost	$ 6,815		$ 6,824
Gross unrealized gains	145		97
Gross unrealized losses	(167)		(229)
Total available-for-sale, fair value	6,793		6,692
Other-than-temporary impairments	(7)	[1]	(10)	[1]
Held To Maturity Securities [Abstract]
Amortized cost	2,793		2,801
Gross unrealized gains	57		31
Gross unrealized losses	(155)		(181)
Total held-to- maturity, fair value	2,695		2,651
Other-Than-Temporary Impairments	0	[1]	0	[1]
US States And Political Subdivisions [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost			0
Gross unrealized gains			0
Gross unrealized losses			0
Total available-for-sale, fair value			0
Other-than-temporary impairments			0	[1]
Corporate Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost			0
Gross unrealized gains			0
Gross unrealized losses			0
Total available-for-sale, fair value			0
Other-than-temporary impairments			0	[1]
Held To Maturity Securities [Abstract]
Amortized cost	2,793		2,801
Gross unrealized gains	57		31
Gross unrealized losses	(155)		(181)
Total held-to- maturity, fair value	2,695		2,651
Other-Than-Temporary Impairments	0	[1]	0	[1]
Residential Mortgage-Backed Non-Agency [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost			0
Gross unrealized gains			0
Gross unrealized losses			0
Total available-for-sale, fair value			0
Other-than-temporary impairments			0	[1]
Collateralized Debt Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost			0
Gross unrealized gains			0
Gross unrealized losses			0
Total available-for-sale, fair value			0
Other-than-temporary impairments			0	[1]
Other Asset-Backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost			0
Gross unrealized gains			0
Gross unrealized losses			0
Total available-for-sale, fair value			0
Other-than-temporary impairments			0	[1]
Money Market Securities [Member]
Available For Sale Securities [Abstract]
Amortized cost	576		781
Gross unrealized gains	0		0
Gross unrealized losses	0		0
Total available-for-sale, fair value	576		781
Other-than-temporary impairments	0	[1]	0	[1]
Money Market Securities [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost	35		136
Gross unrealized gains	0		0
Gross unrealized losses	0		0
Total available-for-sale, fair value	35		136
Other-than-temporary impairments	0	[1]	0	[1]
Perpetual Debt And Equity Securities [Member]
Available For Sale Securities [Abstract]
Amortized cost	11		10
Gross unrealized gains	1		1
Gross unrealized losses	0		0
Total available-for-sale, fair value	12		11
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Amortized cost	6,193		5,897
Gross unrealized gains	144		96
Gross unrealized losses	(167)		(229)
Total available-for-sale, fair value	6,170		5,764
Other-than-temporary impairments	(7)	[1]	(10)	[1]
Fixed Maturities [Member] | Variable Interest Entity Primary Beneficiary [Member]
Held To Maturity Securities [Abstract]
Amortized cost	2,793
Total held-to- maturity, fair value	2,695
Fixed Maturities [Member] | U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Amortized cost	537		528
Gross unrealized gains	24		16
Gross unrealized losses	(7)		(9)
Total available-for-sale, fair value	554		535
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Amortized cost	1,860		1,831
Gross unrealized gains	49		22
Gross unrealized losses	(32)		(73)
Total available-for-sale, fair value	1,877		1,780
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Foreign Governments [Member]
Available For Sale Securities [Abstract]
Amortized cost	266		184
Gross unrealized gains	6		5
Gross unrealized losses	0		0
Total available-for-sale, fair value	272		189
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Amortized cost	1,863		1,682
Gross unrealized gains	33		24
Gross unrealized losses	(34)		(38)
Total available-for-sale, fair value	1,862		1,668
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Amortized cost	1,138		1,167
Gross unrealized gains	10		10
Gross unrealized losses	(22)		(31)
Total available-for-sale, fair value	1,126		1,146
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Amortized cost	72		79
Gross unrealized gains	12		13
Gross unrealized losses	(4)		(5)
Total available-for-sale, fair value	80		87
Other-than-temporary impairments	4	[1]	4	[1]
Fixed Maturities [Member] | Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Amortized cost	38		34
Gross unrealized gains	1		1
Gross unrealized losses	(1)		(1)
Total available-for-sale, fair value	38		34
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Amortized cost	202		205
Gross unrealized gains	4		3
Gross unrealized losses	(55)		(57)
Total available-for-sale, fair value	151		151
Other-than-temporary impairments	(11)	[1]	(14)	[1]
Fixed Maturities [Member] | Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Amortized cost	217		187
Gross unrealized gains	5		2
Gross unrealized losses	(12)		(15)
Total available-for-sale, fair value	210		174
Other-than-temporary impairments	$ 0	[1]	$ 0	[1]

[1] Represents unrealized gains or losses on other than temporarily impaired securities recognized in AOCI, which includes the non-credit component of impairments, as well as all subsequent changes in fair value of such impaired securities reported in AOCI.