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| **Organization, Consolidation and Presentation of Financial Statements [Abstract]**          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] | Note A. GeneralBasis of PresentationThe Condensed Consolidated Financial Statements (Unaudited) include the accounts of CNA Financial Corporation (CNAF) and its subsidiaries.  Collectively, CNAF and its subsidiaries are referred to as CNA or the Company.   Loews Corporation (Loews) owned approximately 90% of the outstanding common stock of CNAF as of March 31, 2015.The accompanying Condensed Consolidated Financial Statements have been prepared in conformity with accounting principles generally accepted in the United States of America (GAAP).  Intercompany amounts have been eliminated.  Certain financial information that is normally included in annual financial statements, including certain financial statement notes, prepared in accordance with GAAP, is not required for interim reporting purposes and has been condensed or omitted.  These statements should be read in conjunction with the Consolidated Financial Statements and notes thereto included in CNAF's Annual Report on Form 10-K filed with the Securities and Exchange Commission for the year ended December 31, 2014, including the summary of significant accounting policies in Note A.  The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the Condensed Consolidated Financial Statements and the reported amounts of revenues and expenses during the reporting periods.  Actual results may differ from those estimates.The interim financial data as of March 31, 2015 and for the three months ended March 31, 2015 and 2014 is unaudited.  However, in the opinion of management, the interim data includes all adjustments, including normal recurring adjustments, necessary for a fair statement of the Company's results for the interim periods.  The results of operations for the interim periods are not necessarily indicative of the results to be expected for the full year.Sale of Continental Assurance Company (CAC)On August 1, 2014, the Company completed the sale of the common stock of CAC, the Company's former life insurance subsidiary.  In the first quarter of 2014, the Company recorded an after-tax impairment loss of $214 million related to the sale.  The Company elected to include CAC cash flow activity in the comparative Condensed Consolidated Statement of Cash Flows.  Further information on discontinued operations is provided in Note K to the Condensed Consolidated Financial Statements. |

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The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.
+ References
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