| **Investments**            | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            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| **Investments [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 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| Investments                | INVESTMENTSThe following table provides cost or amortized cost, gross unrealized gains, gross unrealized losses and fair value for our invested assets:(In millions) Cost or        amortized Gross unrealized FairAt March 31, 2014 cost gains losses valueFixed maturity securities:        States, municipalities and political subdivisions $3,113 $143 $12 $3,244Convertibles and bonds with warrants attached 17 — — 17United States government 7 — — 7Government-sponsored enterprises 211 — 20 191Foreign government 10 — — 10Commercial mortgage-backed  206 2 2 206Corporate  5,045 468 8 5,505Subtotal 8,609 613 42 9,180Equity securities:        Common equities 2,418 1,845 6 4,257Nonredeemable preferred equities 127 43 1 169Subtotal 2,545 1,888 7 4,426Total $11,154 $2,501 $49 $13,606At December 31, 2013        Fixed maturity securities:        States, municipalities and political subdivisions $3,107 $125 $21 $3,211Convertibles and bonds with warrants attached 17 — — 17United States government 7 — — 7Government-sponsored enterprises 227 — 27 200Foreign government 10 — — 10Commercial mortgage-backed  148 — 5 143Corporate  5,122 433 22 5,533Subtotal 8,638 558 75 9,121Equity securities:        Common equities 2,396 1,818 1 4,213Nonredeemable preferred equities 127 38 3 162Subtotal 2,523 1,856 4 4,375Total $11,161 $2,414 $79 $13,496          The net unrealized investment gains in our fixed-maturity portfolio are primarily the result of the continued low interest rate environment that increased the fair value of our fixed-maturity portfolio. The five largest unrealized investment gains in our common stock portfolio are from Exxon Mobil Corporation (NYSE:XOM), The Procter & Gamble Company (NYSE:PG), Honeywell International Incorporated (NYSE:HON), Chevron Corporation (NYSE:CVX), and Dover Corporation (NYSE:DOV), which had a combined gross unrealized gain of $431 million. At March 31, 2014, we had $17 million fair value of hybrid securities included in fixed maturities that follow Accounting Standards Codification (ASC) 815-15-25, Accountingfor Certain Hybrid Financial Instruments, compared with $18 million fair value of hybrid securities at December 31, 2013. The hybrid securities are carried at fair value, and the changes in fair value are included in realized investment gains and losses. The table below provides fair values and gross unrealized losses by investment category and by the duration of the securities’ continuous unrealized loss position:(In millions) Less than 12 months 12 months or more Total Total  Fair Unrealized Fair Unrealized fair unrealizedAt March 31, 2014 value losses value losses value lossesFixed maturity securities:            States, municipalities and political    subdivisions $289 $7 $98 $5 $387 $12United States government 11 — — — 11 —Government-sponsored enterprises 83 8 96 12 179 20Commercial mortgage-backed  55 1 15 1 70 2Corporate  291 7 65 1 356 8Subtotal 729 23 274 19 1,003 42Equity securities:            Common equities 72 6 — — 72 6Nonredeemable preferred equities 39 1 — — 39 1Subtotal 111 7 — — 111 7Total $840 $30 $274 $19 $1,114 $49At December 31, 2013            Fixed maturity securities:            States, municipalities and political    subdivisions $490 $18 $42 $3 $532 $21United States government 1 — — — 1 —Government-sponsored enterprises 199 27 1 — 200 27Foreign government 10 — — — 10 —Commercial mortgage-backed  125 5 — — 125 5Corporate  572 20 43 2 615 22Subtotal 1,397 70 86 5 1,483 75Equity securities:            Common equities 77 1 — — 77 1Nonredeemable preferred equities 42 3 — — 42 3Subtotal 119 4 — — 119 4Total $1,516 $74 $86 $5 $1,602 $79              The following table provides investment income, realized investment gains and losses, the change in unrealized investment gains and losses, and other items:(In millions) Three months ended March 31,  2014 2013Investment income summary:    Interest on fixed maturities $104 $102Dividends on equity securities 32 27Other investment income  1 1Total 137 130Less investment expenses 2 2Total $135 $128     Realized investment gains and losses summary:    Fixed maturities:    Gross realized gains $2 $2Gross realized losses — —Other-than-temporary impairments — (2)Equity securities:    Gross realized gains 18 37Gross realized losses — —Other-than-temporary impairments (1) —Securities with embedded derivatives (1) 1Other 4 3Total $22 $41     Change in unrealized gains and losses summary:    Fixed maturities $88 $(25)Equity securities 29 381Net change in pension actuarial loss and prior service cost (1) 2Adjustment to deferred acquisition costs and life policy reserves (3) 3Other 2 (3)Income taxes on above (41) (125)Total $74 $233      During the three months ended March 31, 2014 and 2013, there were no credit losses on fixed-maturity securities for which a portion of other-than-temporary impairment (OTTI) has been recognized in other comprehensive income. During the quarter ended March 31, 2014, there were two equity securities and one fixed-maturity security other-than-temporarily impaired. At March 31, 2014, ninety-nine fixed-maturity investments with a total unrealized loss of $19 million had been in an unrealized loss position for 12 months or more. Of that total, no fixed-maturity investments had fair values below 70 percent of amortized cost. One equity investment with a total unrealized loss of less than $500,000 had been in an unrealized loss position for 12 months or more as of March 31, 2014.  This equity investment was not trading below 70 percent of cost. During 2013, we other-than-temporarily impaired seven fixed-maturity securities.  At December 31, 2013, forty fixed-maturity investments with a total unrealized loss of $5 million had been in an unrealized loss position for 12 months or more. Of that total, no fixed-maturity investments had fair values below 70 percent of amortized cost. There were no equity investments in an unrealized loss position for 12 months or more as of December 31, 2013. |

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| - Definition
The entire disclosure for  investments in certain debt and equity securities.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -Glossary Debt Security -URI http://asc.fasb.org/extlink&oid=6509901Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27405-111563Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -Glossary Equity Security -URI http://asc.fasb.org/extlink&oid=6511694
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