| **Business Segments (Tables)**                                                                 | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        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| **Segment Reporting [Abstract]**                                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                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| Significant components of the Company's continuing operations and selected balance sheet items | Three months ended             September 30, 2012CNASpecialty CNACommercial Hardy Life &GroupNon-Core Corporate& OtherNon-Core    (In millions)     Eliminations TotalOperating revenues             Net earned premiums$738 $840 $64 $141 $(2) $— $1,781Net investment income159 230 2 201 9 — 601Other revenues58 11 — 1 7 (1) 76Total operating revenues955 1,081 66 343 14 (1) 2,458Claims, Benefits and Expenses             Net incurred claims and benefits460 591 21 350 8 — 1,430Policyholders’ dividends1 3 — 1 — — 5Amortization of deferred acquisition costs156 151 20 6 — — 333Other insurance related expenses73 146 13 35 1 — 268Other expenses53 7 7 8 42 (1) 116Total claims, benefits and expenses743 898 61 400 51 (1) 2,152Operating income (loss) from continuing operations before income tax212 183 5 (57) (37) — 306Income tax (expense) benefit on operating income (loss)(76) (58) (2) 35 11 — (90)Net operating income (loss) from continuing operations attributable to CNA136 125 3 (22) (26) — 216Net realized investment gains (losses), net of participating policyholders’ interests2 10 (1) (3) — — 8Income tax (expense) benefit on net realized investment gains (losses)(2) (3) — 1 1 — (3)Net realized investment gains (losses) attributable to CNA— 7 (1) (2) 1 — 5Net income (loss) from continuing operations attributable to CNA$136 $132 $2 $(24) $(25) $— $221Three months ended           September 30, 2011CNASpecialty CNACommercial Life &GroupNon-Core Corporate& OtherNon-Core   Total(In millions)    Eliminations Operating revenues           Net earned premiums$741 $848 $142 $2 $(1) $1,732Net investment income85 115 190 4 — 394Other revenues56 14 6 — — 76Total operating revenues882 977 338 6 (1) 2,202Claims, Benefits and Expenses           Net incurred claims and benefits485 583 332 (1) — 1,399Policyholders’ dividends(4) 3 2 — — 1Amortization of deferred acquisition costs147 145 5 — — 297Other insurance related expenses75 141 36 1 (1) 252Other expenses48 10 2 42 — 102Total claims, benefits and expenses751 882 377 42 (1) 2,051Operating income (loss) from continuing operations before income tax131 95 (39) (36) — 151Income tax (expense) benefit on operating income (loss)(48) (46) 25 11 — (58)Net operating (income) loss, after-tax, attributable to noncontrolling interests— (2) — — — (2)Net operating income (loss) from continuing operations attributable to CNA83 47 (14) (25) — 91Net realized investment gains (losses), net of participating policyholders’ interests(8) (15) (4) — — (27)Income tax (expense) benefit on net realized investment gains (losses)3 5 1 1 — 10Net realized investment (gains) losses, after-tax, attributable to noncontrolling interests— 1 — — — 1Net realized investment gains (losses) attributable to CNA(5) (9) (3) 1 — (16)Net income (loss) from continuing operations attributable to CNA$78 $38 $(17) $(24) $— $75Nine months ended             September 30, 2012CNASpecialty CNACommercial Hardy (a) Life &GroupNon-Core Corporate& OtherNon-Core    (In millions)     Eliminations TotalOperating revenues             Net earned premiums$2,163 $2,452 $64 $421 $(1) $(1) $5,098Net investment income446 646 2 600 25 — 1,719Other revenues171 31 — 15 14 (1) 230Total operating revenues2,780 3,129 66 1,036 38 (2) 7,047Claims, Benefits and Expenses             Net incurred claims and benefits1,376 1,749 21 1,009 (5) — 4,150Policyholders’ dividends— 9 — 5 — — 14Amortization of deferred acquisition costs458 437 20 22 — — 937Other insurance related expenses222 425 13 106 1 (1) 766Other expenses153 24 7 18 137 (1) 338Total claims, benefits and expenses2,209 2,644 61 1,160 133 (2) 6,205Operating income (loss) from continuing operations before income tax571 485 5 (124) (95) — 842Income tax (expense) benefit on operating income (loss)(197) (164) (2) 86 29 — (248)Net operating income (loss) from continuing operations attributable to CNA374 321 3 (38) (66) — 594Net realized investment gains (losses), net of participating policyholders’ interests18 34 (1) 14 1 — 66Income tax (expense) benefit on net realized investment gains (losses)(6) (12) — (5) — — (23)Net realized investment gains (losses) attributable to CNA12 22 (1) 9 1 — 43Net income (loss) from continuing operations attributable to CNA$386 $343 $2 $(29) $(65) $— $637September 30, 2012             (In millions)             Reinsurance receivables$750 $1,131 $238 $1,297 $2,498 $— $5,914Insurance receivables$676 $1,108 $206 $10 $4 $— $2,004Deferred acquisition costs$306 $278 $19 $— $— $— $603Insurance reserves            Claim and claim adjustment expenses$6,853 $11,226 $466 $2,956 $2,830 $— $24,331Unearned premiums1,698 1,604 243 137 — (1) 3,681Future policy benefits— — — 10,974 — — 10,974Policyholders’ funds13 13 — 139 — — 165_______________________________(a)Included from date of acquisition.Nine months ended           September 30, 2011CNASpecialty CNACommercial Life &GroupNon-Core Corporate& OtherNon-Core   Total(In millions)    Eliminations Operating revenues           Net earned premiums$2,098 $2,418 $427 $1 $(2) $4,942Net investment income371 569 567 24 — 1,531Other revenues164 40 6 4 — 214Total operating revenues2,633 3,027 1,000 29 (2) 6,687Claims, Benefits and Expenses           Net incurred claims and benefits1,333 1,807 985 — — 4,125Policyholders’ dividends(4) 5 5 — — 6Amortization of deferred acquisition costs428 435 17 — — 880Other insurance related expenses216 400 108 4 (2) 726Other expenses140 37 14 129 — 320Total claims, benefits and expenses2,113 2,684 1,129 133 (2) 6,057Operating income (loss) from continuing operations before income tax520 343 (129) (104) — 630Income tax (expense) benefit on operating income (loss)(182) (127) 78 34 — (197)Net operating (income) loss, after-tax, attributable to noncontrolling interests(12) (3) — — — (15)Net operating income (loss) from continuing operations attributable to CNA326 213 (51) (70) — 418Net realized investment gains (losses), net of participating policyholders’ interests7 13 (7) (12) — 1Income tax (expense) benefit on net realized investment gains (losses)(2) (4) 2 5 — 1Net realized investment (gains) losses, after-tax, attributable to noncontrolling interests— — — — — —Net realized investment gains (losses) attributable to CNA5 9 (5) (7) — 2Net income (loss) from continuing operations attributable to CNA$331 $222 $(56) $(77) $— $420December 31, 2011           (In millions)           Reinsurance receivables$852 $1,188 $1,375 $2,677 $— $6,092Insurance receivables$670 $1,047 $8 $1 $— $1,726Deferred acquisition costs$300 $252 $— $— $— $552Insurance reserves           Claim and claim adjustment expenses$6,840 $11,509 $2,825 $3,129 $— $24,303Unearned premiums1,629 1,480 141 — — 3,250Future policy benefits— — 9,810 — — 9,810Policyholders’ funds15 10 166 — — 191 |
| Revenues by line of business                                                                   | Revenues by Line of BusinessPeriods ended September 30Three Months Nine Months(In millions)2012 2011 2012 2011CNA Specialty       International$53 $54 $163 $159Professional & Management Liability700 623 2,039 1,909Surety124 123 364 353Warranty & Alternative Risks80 74 232 219CNA Specialty revenues957 874 2,798 2,640CNA Commercial       CNA Select Risk70 65 208 203Commercial Insurance756 622 2,188 2,015International93 133 274 390Small Business172 142 493 432CNA Commercial revenues1,091 962 3,163 3,040Hardy revenues65  65 Life & Group Non-Core      Health274 274 852 818Life & Annuity64 55 181 170Other2 5 17 5Life & Group Non-Core revenues340 334 1,050 993Corporate & Other Non-Core revenues14 6 39 17Eliminations(1) (1) (2) (2)Total revenues$2,466 $2,175$7,113$6,688                                                                                                                                  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| - Definition
Tabular disclosure of all significant reconciling items in the reconciliation of total revenues from reportable segments to the entity's consolidated revenues.
+ References
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| - Definition
Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.
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