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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, 2014 | Dec. 31, 2013
--- | --- | ---
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | $ 6,748 |  | $ 6,824 |
Gross unrealized gains | 164 |  | 97 |
Gross unrealized losses | (164) |  | (229) |
Total available-for-sale, fair value | 6,748 |  | 6,692 |
Other-than-temporary impairments | (83) | [1] | (10) | [1]
Held To Maturity Securities [Abstract] |  |  |  |
Amortized cost | 2,772 |  | 2,801 |
Gross unrealized gains | 102 |  | 31 |
Gross unrealized losses | (144) |  | (181) |
Total Held-To-Maturity, fair value | 2,730 |  | 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 | 2,772 |  | 2,801 |
Gross unrealized gains | 102 |  | 31 |
Gross unrealized losses | (144) |  | (181) |
Total Held-To-Maturity, fair value | 2,730 |  | 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 | 603 |  | 781 |
Gross unrealized gains | 0 |  | 0 |
Gross unrealized losses | 0 |  | 0 |
Total available-for-sale, fair value | 603 |  | 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 | 0 |  | 136 |
Gross unrealized gains | 0 |  | 0 |
Gross unrealized losses | 0 |  | 0 |
Total available-for-sale, fair value | 0 |  | 136 |
Other-than-temporary impairments | 0 | [1] | 0 | [1]
Perpetual Debt And Equity Securities [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 12 |  | 10 |
Gross unrealized gains | 1 |  | 1 |
Gross unrealized losses | 0 |  | 0 |
Total available-for-sale, fair value | 13 |  | 11 |
Other-than-temporary impairments | 0 | [1] | 0 | [1]
Fixed Maturities [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 6,133 |  | 5,897 |
Gross unrealized gains | 163 |  | 96 |
Gross unrealized losses | (164) |  | (229) |
Total available-for-sale, fair value | 6,132 |  | 5,764 |
Other-than-temporary impairments | (83) | [1] | (10) | [1]
Fixed Maturities [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |
Held To Maturity Securities [Abstract] |  |  |  |
Amortized cost | 2,772 |  |  |
Total Held-To-Maturity, fair value | 2,730 |  |  |
Fixed Maturities [Member] | U S Treasury And Government [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 582 |  | 528 |
Gross unrealized gains | 31 |  | 16 |
Gross unrealized losses | (5) |  | (9) |
Total available-for-sale, fair value | 608 |  | 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 | 1,668 |  | 1,831 |
Gross unrealized gains | 69 |  | 22 |
Gross unrealized losses | (15) |  | (73) |
Total available-for-sale, fair value | 1,722 |  | 1,780 |
Other-than-temporary impairments | 0 | [1] | 0 | [1]
Fixed Maturities [Member] | Foreign Governments [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 273 |  | 184 |
Gross unrealized gains | 6 |  | 5 |
Gross unrealized losses | 0 |  | 0 |
Total available-for-sale, fair value | 279 |  | 189 |
Other-than-temporary impairments | 0 | [1] | 0 | [1]
Fixed Maturities [Member] | Corporate Obligations [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 2,066 |  | 1,682 |
Gross unrealized gains | 36 |  | 24 |
Gross unrealized losses | (91) |  | (38) |
Total available-for-sale, fair value | 2,011 |  | 1,668 |
Other-than-temporary impairments | (79) | [1] | 0 | [1]
Fixed Maturities [Member] | Residential Mortgage-Backed Agency [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 1,125 |  | 1,167 |
Gross unrealized gains | 13 |  | 10 |
Gross unrealized losses | (13) |  | (31) |
Total available-for-sale, fair value | 1,125 |  | 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 | 53 |  | 79 |
Gross unrealized gains | 4 |  | 13 |
Gross unrealized losses | (4) |  | (5) |
Total available-for-sale, fair value | 53 |  | 87 |
Other-than-temporary impairments | (4) | [1] | 4 | [1]
Fixed Maturities [Member] | Commercial Mortgage-Backed [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 25 |  | 34 |
Gross unrealized gains | 1 |  | 1 |
Gross unrealized losses | (1) |  | (1) |
Total available-for-sale, fair value | 25 |  | 34 |
Other-than-temporary impairments | 0 | [1] | 0 | [1]
Fixed Maturities [Member] | Collateralized Debt Obligations [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 120 |  | 205 |
Gross unrealized gains | 0 |  | 3 |
Gross unrealized losses | (22) |  | (57) |
Total available-for-sale, fair value | 98 |  | 151 |
Other-than-temporary impairments | 0 | [1] | (14) | [1]
Fixed Maturities [Member] | Other Asset-Backed [Member] |  |  |  |
Available For Sale Securities [Abstract] |  |  |  |
Amortized cost | 221 |  | 187 |
Gross unrealized gains | 3 |  | 2 |
Gross unrealized losses | (13) |  | (15) |
Total available-for-sale, fair value | 211 |  | 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.

X
- 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. + References No definition available. + Details
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- Definition Amount of accumulated pre-tax unrealized gains before deducting pre-tax unrealized losses on investments in available-for-sale securities impacting investments. + References No definition available. + Details
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- Definition Amount of accumulated pre-tax unrealized losses before deducting pre-tax unrealized gains on investments in available-for-sale securities impacting investments. + References No definition available. + Details
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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. + References No definition available. + Details
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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 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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