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Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Available For Sale Securities [Abstract]
Amortized cost	$ 6,443		$ 6,122
Gross unrealized gains	119		251
Gross unrealized losses	(185)		(152)
Total available-for-sale, fair value	6,377		6,221
Other-than-temporary impairments	(9)	[1]	(20)	[1]
Held To Maturity Securities [Abstract]
Amortized cost	2,809		2,829
Gross unrealized gains	8		2
Gross unrealized losses	(251)		(157)
Total held-to- maturity, fair value	2,566		2,674
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			38
Gross unrealized gains			3
Gross unrealized losses			0
Total available-for-sale, fair value			41
Other-than-temporary impairments			0	[1]
Corporate Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost			177
Gross unrealized gains			9
Gross unrealized losses			(6)
Total available-for-sale, fair value			180
Other-than-temporary impairments			0	[1]
Held To Maturity Securities [Abstract]
Amortized cost	2,809		2,829
Gross unrealized gains	8		2
Gross unrealized losses	(251)		(157)
Total held-to- maturity, fair value	2,566		2,674
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			92
Gross unrealized gains			0
Gross unrealized losses			(10)
Total available-for-sale, fair value			82
Other-than-temporary impairments			0	[1]
Collateralized Debt Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost			97
Gross unrealized gains			0
Gross unrealized losses			(8)
Total available-for-sale, fair value			89
Other-than-temporary impairments			0	[1]
Other Asset-Backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Available For Sale Securities [Abstract]
Amortized cost			23
Gross unrealized gains			0
Gross unrealized losses			0
Total available-for-sale, fair value			23
Other-than-temporary impairments			0	[1]
Money Market Securities [Member]
Available For Sale Securities [Abstract]
Amortized cost	911		580
Gross unrealized gains	0		0
Gross unrealized losses	0		0
Total available-for-sale, fair value	911		580
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	156		210
Gross unrealized gains	0		0
Gross unrealized losses	0		0
Total available-for-sale, fair value	156		210
Other-than-temporary impairments	0	[1]	0	[1]
Perpetual Debt And Equity Securities [Member]
Available For Sale Securities [Abstract]
Amortized cost	9		22
Gross unrealized gains	1		1
Gross unrealized losses	0		0
Total available-for-sale, fair value	10		23
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Amortized cost	5,367		4,883
Gross unrealized gains	118		238
Gross unrealized losses	(185)		(128)
Total available-for-sale, fair value	5,300		4,993
Other-than-temporary impairments	(9)	[1]	(20)	[1]
Fixed Maturities [Member] | Variable Interest Entity Primary Beneficiary [Member]
Held To Maturity Securities [Abstract]
Amortized cost	2,809
Total held-to- maturity, fair value	2,566
Fixed Maturities [Member] | U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Amortized cost	526		819
Gross unrealized gains	19		40
Gross unrealized losses	(8)		(1)
Total available-for-sale, fair value	537		858
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Amortized cost	1,632		1,446
Gross unrealized gains	30		97
Gross unrealized losses	(52)		(12)
Total available-for-sale, fair value	1,610		1,531
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Foreign Governments [Member]
Available For Sale Securities [Abstract]
Amortized cost	192		183
Gross unrealized gains	9		13
Gross unrealized losses	0		0
Total available-for-sale, fair value	201		196
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Amortized cost	1,616		1,058
Gross unrealized gains	32		54
Gross unrealized losses	(26)		(20)
Total available-for-sale, fair value	1,622		1,092
Other-than-temporary impairments	0	[1]	5	[1]
Fixed Maturities [Member] | Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Amortized cost	942		939
Gross unrealized gains	10		19
Gross unrealized losses	(18)		(1)
Total available-for-sale, fair value	934		957
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Amortized cost	67		86
Gross unrealized gains	13		11
Gross unrealized losses	(6)		(8)
Total available-for-sale, fair value	74		89
Other-than-temporary impairments	3	[1]	0	[1]
Fixed Maturities [Member] | Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Amortized cost	34		46
Gross unrealized gains	1		0
Gross unrealized losses	(1)		(4)
Total available-for-sale, fair value	34		42
Other-than-temporary impairments	0	[1]	0	[1]
Fixed Maturities [Member] | Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Amortized cost	210		161
Gross unrealized gains	2		1
Gross unrealized losses	(57)		(71)
Total available-for-sale, fair value	155		91
Other-than-temporary impairments	(12)	[1]	(25)	[1]
Fixed Maturities [Member] | Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Amortized cost	148		145
Gross unrealized gains	2		3
Gross unrealized losses	(17)		(11)
Total available-for-sale, fair value	133		137
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.

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- Definition

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.

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Amount of accumulated pre-tax unrealized gains before deducting pre-tax unrealized losses on investments in available-for-sale securities impacting investments.

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Amount of accumulated pre-tax unrealized losses before deducting pre-tax unrealized gains on investments in available-for-sale securities impacting investments.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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