Investments (Distribution Of Securities By Percentage Of Fair Value Below Book Value By More Than 5%) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Available For Sale Securities [Abstract]
Fixed-maturity securities held as available-for-sale, amortized cost	$ 6,815	$ 6,824
Available For Sale Securities	6,793	6,692
Held To Maturity Securities [Abstract]
Held-To-Maturity Securities Amortized Cost	2,793	2,801
Held-To-Maturity Securities Fair Value	2,695	2,651
> 5% To 15% [Member]
Held To Maturity Securities [Abstract]
Percentage Of Fair Value Below Book Value Minimum	5.00%
Percentage Of Fair Value Below Book Value Maximum	15.00%
> 5% To 15% [Member] \| Unrealized loss position > 12 months
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position	25
Fixed-maturity securities held as available-for-sale, amortized cost	263
Available For Sale Securities	245
Held To Maturity Securities [Abstract]
Number of Held-To-Maturity Securities in unrealized loss position	0
Held-To-Maturity Securities Amortized Cost	0
Held-To-Maturity Securities Fair Value	0
> 15% To 25% [Member]
Held To Maturity Securities [Abstract]
Percentage Of Fair Value Below Book Value Minimum	15.00%
Percentage Of Fair Value Below Book Value Maximum	25.00%
> 15% To 25% [Member] \| Unrealized loss position > 12 months
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position	11
Fixed-maturity securities held as available-for-sale, amortized cost	105
Available For Sale Securities	83
Held To Maturity Securities [Abstract]
Number of Held-To-Maturity Securities in unrealized loss position	0
Held-To-Maturity Securities Amortized Cost	0
Held-To-Maturity Securities Fair Value	0
> 25% To 50% [Member]
Held To Maturity Securities [Abstract]
Percentage Of Fair Value Below Book Value Minimum	25.00%
Percentage Of Fair Value Below Book Value Maximum	50.00%
> 25% To 50% [Member] \| Unrealized loss position > 12 months
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position	4
Fixed-maturity securities held as available-for-sale, amortized cost	21
Available For Sale Securities	15
Held To Maturity Securities [Abstract]
Number of Held-To-Maturity Securities in unrealized loss position	1
Held-To-Maturity Securities Amortized Cost	575
Held-To-Maturity Securities Fair Value	420
> 50% [Member]
Held To Maturity Securities [Abstract]
Percentage Of Fair Value Below Book Value Minimum	50.00%
> 50% [Member] \| Unrealized loss position > 12 months
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position	7
Fixed-maturity securities held as available-for-sale, amortized cost	49
Available For Sale Securities	8
Held To Maturity Securities [Abstract]
Number of Held-To-Maturity Securities in unrealized loss position	0
Held-To-Maturity Securities Amortized Cost	0
Held-To-Maturity Securities Fair Value	0
Greater Than 5% [Member] \| Unrealized loss position > 12 months
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position	47
Fixed-maturity securities held as available-for-sale, amortized cost	438
Available For Sale Securities	351
Held To Maturity Securities [Abstract]
Number of Held-To-Maturity Securities in unrealized loss position	1
Held-To-Maturity Securities Amortized Cost	575
Held-To-Maturity Securities Fair Value	$ 420

Percentage Of Fair Value Below Book Value Maximum

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Percentage Of Fair Value Below Book Value Minimum

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

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-Topic 320

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

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Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

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-Paragraph 5

-Subparagraph (f)

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-Topic 944

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

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Fair value of investments in debt securities classified as held-to-maturity.

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Disclosure regarding factors used to determine that the impairment of securities categorized as held-to-maturity where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the held-to-maturity investments determined to be temporarily impaired.

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