TOTAL INVESTED ASSETS Cash Assets TOTAL ASSETS TOTAL ASSETS Other Assets Other Assets Other Assets Goodwill Premiums Receivable Reinsurance Recoverable on Unpaid Losses and Loss Expenses Prepaid Reinsurance Premiums Deferred Policy Acquisition Costs Accrued Investment Income Unearned Premiums Liabilities and Stockholders' Equity TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY Stockholders' Equity Attributable to Parent TOTAL SHAREHOLDERS' EQUITY TOTAL SHAREHOLDERS' EQUITY Liabilities TOTAL LIABILITIES TOTAL LIABILITIES Long Term Debt Accrued Expenses and Other Liabilities Common Stock - $1 Par Value; 371,980,460 Shares Common Stock - $1 Par Value; 371,980,710 and 374,649,923 Shares Common Stock, Value, Ending Balance Common Stock, Value, Beginning Balance Common Stock, Value, Total Common Stock, Par Value Treasury Stock, Shares Treasury Stock, at Cost - 16,279,184 Shares in 2008 Treasury Stock, at Cost - 67,047,923 and 39,972,796 Shares Treasury Stock, at Cost - 67,047,923 and 39,972,796 Shares Treasury Stock, Value, Ending Balance Treasury Stock, Value, Beginning Balance Accumulated Other Comprehensive Income Accumulated Other Comprehensive Income (Loss) Retained Earnings Common Stock, Shares, Outstanding Interest And Dividend Income Operating Investment income Interest and Dividend Income, Operating, Total Investment Income Other Income Other Revenues Revenues Total Revenues Total Revenues Gain (Loss) on Investments Realized Investment Losses (Gains), Net Total Realized Gains (Losses), Net Total invested assets Total Realized Gains (Losses), Net Realized investment gains (losses), net Dividends Declared Per Share Amortization of Deferred Policy Acquisition Costs Income (Loss) from Continuing Operations before Income Taxes, Minority Interest, and Income (Loss) from Equity Method Investments Total income before income tax Income Before Federal and Foreign Income Tax Net Income Earnings Per Share, Basic Basic earnings per share Basic Earnings Per Share, Diluted Diluted earnings per share Diluted Investment Expenses Comprehensive Income Comprehensive Income, Net of Tax, Attributable to Parent Net Income Net Cash Provided by (Used in) Operating Activities Net Cash Provided by Operating Activities Net Cash Provided by Operating Activities Net Cash Provided by Operating Activities Increase decrease in other operating capital net Other, Net Other, Net Other, Net Depreciation Amortization of Premiums and Discounts on Fixed Maturities Amortization of Premiums and Discounts on Fixed Maturities Amortization of Premiums and Discounts on Fixed Maturities Increase (Decrease) in Unearned Premiums, Net Decrease in Unearned Premiums, Net Decrease in Premiums Receivable Decrease in Premiums Receivable Increase in Premiums Receivable Net Cash Provided by (Used in) Investing Activities Net Cash Used in Investing Activities Net Cash Used in Investing Activities Net Cash Used in Investing Activities Net Cash Provided by (Used in) Investing Activities Payments for proceeds from other investing activities Other, Net Other, Net Other, Net Other, Net Net Cash Provided by (Used in) Financing Activities Net Cash Used in Financing Activities Net Cash Used in Financing Activities Net Cash Used in Financing Activities Purchases of Equity Securities Other Expenses Other Comprehensive Income (Loss), Net of Tax, Period Increase (Decrease) Change During Year, Net of Tax Total Other Comprehensive Income, Net of Tax Total Other Comprehensive Income (Loss), Net of Tax Dividends Paid to Shareholders Dividends Paid to Shareholders Dividends Paid to Shareholders Dividends Paid to Shareholders Repurchase of Shares Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans Tax Exempt Tax exempt, Fair value Tax exempt, Fair value Tax Exempt (cost $18,894 and $18,720) This item represents total tax-exempt debt securities that are categorized as neither held-to-maturity nor trading. Such securities are reported at fair value; unrealized gains and losses of such securities are excluded from earnings and included in other comprehensive income. Taxable Taxable, Fair value Taxable, Fair value Taxable (cost $16,071 and $16,470) This item represents total taxable debt securities that are categorized as neither held-to-maturity nor trading. Such securities are reported at fair value; unrealized gains and losses of such securities are excluded from earnings and included in other comprehensive income. Taxable, Cost Taxable fixed maturities, Cost Taxable, Cost This item represents the amortized cost basis of taxable debt securities that are categorized as neither held-to-maturity nor trading. Equity Securities, Cost This item represents the amortized cost basis of equity securities. Equity securities, Cost Equity Securities, Cost Tax Exempt Cost Tax exempt, cost Tax Exempt, Cost This item represents the amortized cost basis of tax exempt debt securities that are categorized as neither held-to-maturity nor trading. Purchases of Property and Equipment, Net Segments Information Contingent Liabilities Federal and Foreign Income Tax Purchases of Fixed Maturities Fixed Maturities Abstract Fixed Maturities [Abstract] Fixed Maturities Shareholders' Equity Shareholders' Equity Liabilities Abstract Liabilities [Abstract] Liabilities Assets Abstract Assets [Abstract] Assets Earnings Per Share [Abstract] Revenues Abstract Revenues [Abstract] Revenues Other Comprehensive Income (Loss), Net of Tax Cash Flows from Investing Activities Cash Flows from Financing Activities Cash Flows from Operating Activities Short Term Investments Equity Securities (cost $1,660 and $1,907) Equity securities Equity securities, Fair value Equity Securities (cost $1,253 and $1,215) Accrued Expenses and Other Liabilities Accrued Expenses and Other Liabilities Accrued Expenses and Other Liabilities Losses and Loss Expenses Other Insurance Operating Costs and Expenses Proceeds From Sale Of Available For Sale Securities, Debt Proceeds from Fixed Maturities - Sales Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities Proceeds from Fixed Maturities - Maturities, Calls and Redemptions Segments Information [Abstract] Segments Information [Abstract] Contingent Liabilities [Abstract] Contingent Liabilities [Abstract] Adoption of New Accounting Pronouncement Adoption of New Accounting Pronouncements Entity Common Stock, Shares Outstanding (actual number of shares) Corporate Expenses Corporate Expenses The total amount of expenses incurred by the entity related to corporate activities, including interest expese. Total Losses and Expenses Total Losses and Expenses The total amount of losses and expenses recognized during the period. Proceeds from Sales of Equity Securities Proceeds from Sale of Available-for-sale Securities, Equity General General Total Losses and Expenses Federal and Foreign Income Tax Income Tax Expense (Benefit) Long Term Debt Long-term Debt Retained Earnings Retained Earnings (Accumulated Deficit), Beginning Balance Retained Earnings (Accumulated Deficit), Ending Balance Retained Earnings (Accumulated Deficit) Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance Accumulated Other Comprehensive Income (Loss), Net of Tax Net Income Purchases of Property and Equipment, Net Payments to Acquire Property, Plant, and Equipment Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans Other Invested Assets Other Invested Assets Other Invested Assets This item represents other invested assets, including private equity limited partnerships, which are carried at the Corporation's equity in the net assets of the partnerships. Unpaid Losses and Loss Expenses Liability for Claims and Claims Adjustment Expense, Property Casualty Liability Paid-In Surplus Additional Paid in Capital, Total Additional Paid in Capital, Beginning Balance Additional Paid in Capital, Ending Balance Additional Paid in Capital Investments in Other Invested Assets, Net Payments for (Proceeds from) Limited Partnership Increase in Short Term Investments, Net Payments for (Proceeds from) Short-term Investments, Total Payments for (Proceeds from) Short-term Investments Change In Net Payable Receivable From Security Transactions Not Settled Increase in Net Payable from Security Transactions Not Settled Increase in Net Payable from Security Transactions Not Settled Increase in Net Payable from Security Transactions Not Settled Change in net receivable or payable from security transactions not settled. Premiums Earned, Net, Property and Casualty Total Premiums Earned Premiums Earned, Net, Property and Casualty, Total Premiums Earned Corporate Expenses TOTAL INVESTED ASSETS Investments Increase in Unpaid Losses and Loss Expenses, Net Increase (Decrease) in Property and Casualty Insurance Liabilities Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans Increase in Short Term Investments, Net Purchases of Fixed Maturities Purchases of Equity Securities Purchases of Property and Equipment, Net Repurchase of Shares Common Stock, Shares Issued Common Stock, Shares, Outstanding, Total Treasury Stock, Shares Treasury Stock, Shares, Beginning Balance Treasury Stock, Shares, Ending Balance Investments in Other Invested Assets, Net Cash Accrued Investment Income Accrued Investment Income Receivable, Total Premiums Receivable Premiums Receivable, at Carrying Value, Total Reinsurance Recoverable on Unpaid Losses and Loss Expenses Prepaid Reinsurance Premiums Deferred Policy Acquisition Costs Deferred Policy Acquisition Costs, Total Goodwill Goodwill, Beginning Balance Goodwill, Ending Balance Unearned Premiums Unearned Premiums, Total Invested Assets [Abstract] Invested Assets Fair Values of Financial Instruments [Abstract] Fair Values Of Financial Instruments [Abstract] Fair Values of Financial Instruments Fair Value Disclosures [Text Block] Cash Flows from Operating Activities Depreciation Cash Flows from Investing Activities Purchases of Fixed Maturities Purchases of Equity Securities Repurchase of Shares Short Term Investments Losses and Loss Expenses Amortization of Deferred Policy Acquisition Costs Deferred Policy Acquisition Cost, Amortization Expense, Total Other Insurance Operating Costs and Expenses Investment Expenses Other Expenses Other Nonoperating Expense, Total Net Income Per Share Dividends Declared Per Share Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Commitments and Contingencies Contingent Liabilities (Note 7) Cash Flows from Financing Activities Other Comprehensive Income (Loss), Net of Tax Common Stock, Par Value Change In Unrealized Other Than Temporary Impairments Of Investments Change in Unrealized Other-Than-Temporary Impairment Losses on Investments Change in Unrealized Other-Than-Temporary Impairments of Investments This item represents the non-credit impairment losses portion of other-than-temporary impairments on fixed maturity investments in which a credit loss was recognized in the Consolidated Statements of Income. This item includes the impact of subsequent changes to these securities such as appreciation or loss in value or subsequent sale of the security. Realized Gains Losses Net Abstract Realized Investment Gains (Losses), Net Other Realized Gains (Losses), Net Other Realized Investment Gains (Losses), Net Other Realized Investment Gains (Losses), Net This item represents the net total realized gain (loss) included in earnings for the period as a result of selling or holding invested assets. Total Realized Gains (Losses), Net Total Other-than-Temporary Impairment Losses on Investments Total Realized Gains (Losses), Net Earnings Per Share Earnings Per Share [Text Block] Invested Assets Available-for-sale Securities [Text Block] Other than Temporary Impairment Losses on Investments Recognized in Other Comprehensive Income Other-Than-Temporary Impairment Losses on Investments Recognized in Other Comprehensive Income Other-than-Temporary Impairment Losses on Investments Recognized in Other Comprehensive Income This item represents the non-credit impairment loss portion of the total other-than-temporary impairment losses on investments for fixed maturity investments that the Corporation does not intend to sell or it is not more likely than not the Corporation will be required to sell these securities before they recover to their amortized cost value. This amount offsets the amount included in the total other-than-temporary impairment losses on investments and recognized in accumulated other comprehensive income. Dividend Payable to Shareholders Dividends Payable Change in Unrealized Appreciation or Depreciation of Investments Other Comprehensive Income, Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent, Total Other Comprehensive Income, Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Change in Unrealized Other-Than-Temporary Impairments Losses on Investments Foreign Currency Translation Gains (Losses) Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent, Total Other Comprehensive Income, Defined Benefit Plans Adjustment, Net of Tax, Portion Attributable to Parent Amortization of Net Loss and Prior Service Cost Included in Net Postretirement Benefit Costs Amortization of Net Loss and Prior Service Cost Included in Net Postretirement Benefit Costs Total Other-Than-Temporary Impairment Losses on Investments Segments Information Contingent Liabilities Cash at Beginning of Year Cash at End of Period Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Cash Period Increase Decrease Net Increase (Decrease) in Cash Net Increase in Cash The net change between the beginning and ending balance of unrestricted cash available for day-to-day operating needs. Accumulated Other Comprehensive Income (Loss), End of Year Consolidated Balance Sheets [Abstract] Consolidated Statements of Income [Abstract] Consolidated Statements of Comprehensive Income Consolidated Statements of Cash Flows [Abstract] General (Policies) [Abstract] Adoption of New Accounting Pronouncement [Abstract] Fair Values of Financial Instruments (Details) [Abstract] Fair Values Of Financial Instruments Details. Carrying Values and Fair Values of Financial Instruments [Abstract] Carrying values and fair values of financial instruments. Invested assets [Abstract] Investments [Abstract] Long term debt Short term investments Fair Values of Fixed Maturities and Equity Securities [Abstract] Level 1 [Member] Level 1 [Member] Level 2 [Member] Level 2 [Member] Level 3 [Member] Level 3 [Member] Fair Values of Financial Instruments (Tables) [Abstract] Fair Values of Fixed Maturities and Equity Securities Text Block Fair Values of Fixed Maturities and Equity Securities Based Upon the Lowest Level of Input Fair Values of fixed maturities and equity securities categorized based upon the lowest level of input that was significant to the fair value measurement. Carrying Values and Fair Values of Financial Instruments Fair Value, by Balance Sheet Grouping [Text Block] Invested Assets (Details) [Abstract] Invested Assets Details. Amortized Cost And Fair Value Of Invested Assets Abstract Amortized cost and fair value of fixed maturities and equity securities [Abstract] Realized investment gains and losses [Abstract] Realized investment gains and losses [Abstract] Invested Assets (Textuals) [Abstract] Invested Assets (Textuals) [Abstract] Invested Assets (Tables) [Abstract] Change In Unrealized Appreciation Or Depreciation Of Investments Fair Value Text Block Change in unrealized appreciation or depreciation of investments carried at fair value Change in unrealized appreciation or depreciation of investments carried at fair value, including the change in unrealized other-than-temporary impairment losses. Tax exempt, Gross unrealized depreciation The excess of amortized cost of tax exempt fixed maturities over its fair value which deficiency has not been recognized in earnings of the entity. Tax exempt, Gross unrealized depreciation Tax exempt, Gross unrealized depreciation Taxable, Gross unrealized appreciation The excess of the fair value of taxable fixed maturities over its amortized cost which excess value has not been recognized in earnings of the entity. Taxable, Gross unrealized appreciation Taxable, Gross unrealized depreciation The excess of amortized cost of taxable fixed maturities over its fair value which deficiency has not been recognized in earnings of the entity. Taxable, Gross unrealized depreciation Taxable, Gross unrealized depreciation Fixed Maturities Cost Total fixed maturities, Cost Total fixed maturities, Cost This item represents the amortized cost basis of investments in debt securities having predetermined or determinable maturity dates. Fixed maturities, Gross unrealized appreciation The excess of the fair value of fixed maturities over its amortized cost which excess value has not been recognized in earnings of the entity. Total fixed maturities, Gross unrealized appreciation Fixed maturities, Gross unrealized appreciation Fixed maturities, Gross unrealized depreciation Total fixed maturities, Gross unrealized depreciation Total fixed maturities, Gross unrealized depreciation Fixed maturities, Gross unrealized depreciation The excess of amortized cost of fixed maturities over its fair value which deficiency has not been recognized in earnings of the entity. Equity securities, Gross unrealized appreciation The excess of the fair value of equity securities over its amortized cost which excess value has not been recognized in earnings of the entity. Equity securities, Gross unrealized appreciation Equity securities, Gross unrealized appreciation Equity securities, Gross unrealized depreciation The excess of amortized cost of equity securities over its fair value which deficiency has not been recognized in earnings of the entity. Equity securities, Gross unrealized depreciation Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Due in one year or less, Cost Available-for-sale Securities, Debt Maturities, within One Year, Fair Value Due in one year or less, Fair value Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost Due after one year through five years, Cost Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value Due after one year through five years, Fair value Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Due after five years through ten years, Cost Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value Due after five years through ten years, Fair value Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Due after ten years, Cost Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value Due after ten years, Fair value Available-for-sale Securities, Debt Maturities, Amortized Cost Subtotal fixed maturities, Cost Available-for-sale Securities, Debt Maturities, Fair Value Subtotal fixed maturities, Fair value Fixed maturities, Unrealized appreciation (depreciation), Net The net excess or deficiency of the fair value of fixed maturities over or under its amortized cost which has not been recognized in earnings of the entity. Equity securities, Unrealized appreciation (depreciation), Net Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss) Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Total Change in unrealized appreciation or depreciation of fixed maturities and equity securities Deferred income tax Available-for-sale Securities, Income Tax Expense on Change in Unrealized Holding Gain or Loss Total fixed maturities and equity securities, Net of tax Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax Less than twelve months [Member] Less Than Twelve Months Member. Twelve months or more [Member] Twelve Months Or More Member. U S Government and Government Agency and Authority Obligations [Member] US Government and Government Agency and Authority Obligations [Member] US Government And Government Agency And Authority Obligations Member. Tax exempt, Gross unrealized appreciation The excess of the fair value of tax exempt fixed maturities over its amortized cost which excess value has not been recognized in earnings of the entity. Tax exempt, Gross unrealized appreciation Commercial Mortgage-Backed Securities [Member] Residential Mortgage-Backed Securities [Member] Adoption of New Accounting Pronouncements (Policies) [Abstract] Adoption of New Accounting Pronouncements (Policies) [Abstract] Adopted New Guidance Other Than Temporary Impairments [Text Block] Effective April 1, 2009, the Corporation adopted a new guidance related to the recognition and presentation of other-than-temporary impairments Describes an entity's accounting policy regarding recognition and presentation of other-than-temporary impairments. Document Fiscal Year Focus Document Fiscal Period Focus Corporate bonds [Member] Investment Type [Axis] Investment Type [Domain] Earnings Per Share [Details] [Abstract] Earnings Per Share Details Abstract. Earnings Per Share, Basic [Abstract] Basic earnings per share [Abstract] Basic earnings per share: Weighted average shares outstanding Weighted Average Number of Shares Outstanding, Basic Weighted average shares outstanding Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share Weighted Average Number of Shares Outstanding, Diluted Segments Information [Details] [Abstract] Segments Information. Earnings Per Share, Diluted Abstract Diluted earnings per share [Abstract] Diluted earnings per share: Earnings Per Share (Tables) [Abstract] Earnings Per Share Computation of basic and diluted earnings per share [Text Block] A table disclosing the computation of basic and diluted earnings per share. Computation of basic and diluted earnings per share Segments Information (Tables) [Abstract] Revenues And Income Before Income Tax Of Operating Segments Text Block Revenues and income before income tax of the operating segments A table disclosing the revenues and income before income tax of the operating segments. Income Before Income Tax Abstract Income before income tax [Abstract] Income before income tax Total insurance [Member] Total insurance. Specialty insurance [Member] The specialty segment includes those classes of business that are available in more limited markets since they require specialized underwriting and claim settlement. Specialty classes include professional liability coverages and surety. Segment Reporting Information, by Segment [Axis] Reporting Segment [Domain] Additional shares from assumed exercise of stock-based compensation awards Incremental Common Shares Attributable to Share-based Payment Arrangements Underwriting [Member] Underwriting member. Components Of Unrealized Appreciation Or Depreciation Of Investments Text Block Components of unrealized appreciation or depreciation of investments Components of unrealized appreciation and depreciation, including unrealized other-than-temporary impairment losses, of investments carried at fair value. Document and Entity Information [Abstract] Document and Entity Information. Available For Sale Securities In Unrealized Loss Position [Axis] Available For Sale Securities In Unrealized Loss Position. Available For Sale Securities In Unrealized Loss Position [Domain] Available For Sale Securities In Unrealized Loss Position. Foreign government and government agency obligations [Member] Foreign government and government agency obligations. Fair Value, Assets Measured on Recurring Basis, Disclosure Items [Axis] Fair Value, Assets Measured on Recurring Basis, Disclosure Items [Domain] Supplementary Insurance Information By Segment [Line Items] Schedule of Segment Reporting Information, by Segment [Table] Supplementary Insurance Information, Segment Name [Axis] Supplementary Insurance Information, Segment Name [Domain] Premiums Earned From Insurance Premiums earned related to insurance business Premiums recognized as revenue in the period earned on all property and casualty insurance and reinsurance contracts after subtracting any amounts ceded to another insurer and before reinsurance assumed business which is in run-off. Premiums Earned From Reinsurance Assumed Premiums recognized as revenue in the period earned on property and casualty reinsurance assumed business which is in run-off, after subtracting any amounts ceded to another insurer. Premiums earned related to reinsurance assumed Reinsurance Assumed Underwriting Income Reinsurance assumed underwriting income Amount of underwriting income (loss) for reinsurance assumed segment, which is in run-off, which is arrived at by reducing premiums earned by losses and loss expenses incurred and statutory underwriting expenses incurred. Under statutory accounting principles, policy acquisition and other underwriting expenses are recognized immediately, not at the time premiums are earned. Statutory Underwriting Income Amount of underwriting income (loss) for the property and casualty insurance segments which is arrived at by reducing premiums earned by losses and loss expenses incurred and statutory underwriting expenses incurred. Under statutory accounting principles, policy acquisition and other underwriting expenses are recognized immediately, not at the time premiums are earned. Statutory underwriting income Total Underwriting Income Underwriting income Amount of underwriting income (loss) for the property and casualty insurance segments which is arrived at by reducing premiums earned by losses and loss expenses incurred and generally accepted accounting principles (GAAP) underwriting expenses incurred. Under GAAP, policy acquisition expenses are deferred and amortized over the period in which the related premiums are earned. Other Income Charges Other Charges Reflects the sum of all other income and charges recognized by the entity in the period not otherwise specified separately. Total property and casualty insurance revenues Total revenues recognized in the period for property and casualty insurance including premiums earned and investment income before realized investment gains or losses. Investment income Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums net of expenses related to the generation of investment income in debt and equity securities. Corporate and Other Income Loss Corporate and other loss Represents income (loss) before income tax related to non-insurance companies before realized investment gain (loss). Property and Casualty Insurance Income Before Taxes And Corporate Companies Amount of income (loss) before income tax for property and casualty insurance including underwriting income (loss), investment income (loss) and other income (charges), before realized investment gain (loss). Total property and casualty insurance Insurance Underwriting Income Underwriting income related to insurance business Amount of underwriting income (loss) for the reportable segments which is arrived at by reducing premiums earned by losses and loss expenses incurred and statutory underwriting expenses incurred, before reinsurance assumed business which is in run-off. Under statutory accounting principles, policy acquisition and other underwriting expenses are recognized immediately, not at the time premiums are earned. Segment Reporting, Amount Per Revenue Reconciling Item [Axis] Segment Reporting, Revenue Reconciling Item, Name [Domain] Adopted New Guidance Related To Accounting For Variable Interest Entity Text Block Effective January 1, 2010, the Corporation adopted new guidance related to the accounting for variable interest entity Describes an entity's accounting policy related to the accounting for a variable interest entity. Property and casualty insurance [Member] Property and casualty insurance Member. Commercial insurance [Member] The commercial segment includes those classes of business that are generally available in broad markets and are of a more commodity nature. Commercial classes include multiple peril, casualty, workers' compensation and property and marine. Personal insurance [Member] The personal segment targets the personal insurance market. Personal classes include automobile, homeowners and other personal coverages. Corporate and other revenues Corporate and other revenues Represents revenues related to non-insurance companies, before realized investment gains or losses. Marketable Securities Total fixed maturities and equity securities Total fixed maturities and equity securities, Fair value Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Table] Gross Realized Gains Fixed Maturities Fixed maturities, Gross realized gains This item represents the gross profit realized on the sale of fixed maturities categorized neither as held-to-maturity nor trading securities. Gross Realized Losses Fixed Maturities Fixed maturities, Gross realized losses This item represents the gross loss realized on the sale of fixed maturities categorized neither as held-to-maturity nor trading securities. Impairment of Investments Fixed Maturities Fixed maturities, Other-than-temporary impairment losses The amount charged to income if the decline in fair value for fixed maturities is deemed to be other than temporary. Gross Gain Loss Otti Total Fixed Maturities Total fixed maturities Total fixed maturities The total gross realized gain or loss, net, for fixed maturities included in earnings for the period. Deferred Income Tax Asset Liability Deferred income tax liability Deferred income tax liability The amount for all deferred tax assets and liabilities relating to unrealized appreciation or depreciation as of the balance sheet date. Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net of tax The net excess or deficiency of the fair value of fixed maturities and equity securities over or under its amortized cost which has not been recognized in earnings of the entity net of deferred income tax. Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net of tax Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net of tax Fixed Maturities Change In Unrealized Appreciation Or Depreciation Change in unrealized appreciation or depreciation of fixed maturities This item represents the change in net unrealized holding gain or loss on fixed maturities that has been included in accumulated other comprehensive income, a separate component of shareholders' equity, during the period. Equity Securities Change In Unrealized Appreciation Or Depreciation Change in unrealized appreciation or depreciation of equity securities This item represents the change in net unrealized holding gain or loss on equity securities that has been included in accumulated other comprehensive income, a separate component of shareholders' equity, during the period. Gross Realized Gains Equity Securities Equity securities, Gross realized gains This item represents the gross profit realized on the sale of equity securities categorized neither as held-to-maturity nor trading securities. Gross Gain Loss Otti Equity Securities Total Total equity securities The total gross realized gain or loss, net, for equity securities included in earnings for the period. Other Invested Assets Gain Loss Other invested assets Other invested assets This item represents the gross realized gain (loss) included in earnings for the period as a result of selling or holding other invested assets. Individual fixed maturity and equity securities in unrealized loss position Individual fixed maturity security and equity securities which were in an unrealized loss position. Individual fixed maturity and equity securities in unrealized loss position Individual fixed maturities in unrealized loss position Individual fixed maturities which were in an unrealized loss position. Individual fixed maturities in unrealized loss position Fixed Maturities Equity Securities Gross Unrealized Depreciation Total fixed maturities and equity securities, Gross unrealized depreciation The excess of amortized cost of fixed maturities and equity securities over its fair value which deficiency has not been recognized in earnings of the entity. Amortized Cost and Fair Value of Fixed Maturities and Equity Securities Text Block Amortized cost and fair value of fixed maturities and equity securities Amortized cost and fair value of fixed maturities and equity securities by investment category. Amortized Cost And Fair Value Of Fixed Maturities By Contractual Maturity Text Block Amortized cost and fair value of fixed maturities by contractual maturity Amortized cost and fair value of fixed maturities by contractual maturity. Fair Value And Gross Unrealized Depreciation Of Investments In An Unrealized Loss Position Text Block Fair value and gross unrealized depreciation of investments in an unrealized loss position The aggregate fair value and gross unrealized depreciation, including other-than-temporary impairment losses, by investment category and length of time that individual securities have continuously been in an unrealized loss position for all investment securities in an unrealized loss position. Gain (Loss) on Investments [Text Block] Realized investment gains and losses Increase (Decrease) in Funds Held under Reinsurance Agreements Increase in Funds Held Under Deposit Contracts Increase (Decrease) in Funds Held Under Deposit Contracts Equity securities, Unrealized appreciation (depreciation), Net The net excess or deficiency of the fair value of equity securities over or under its amortized cost which has not been recognized in earnings of the entity. Equity securities, Unrealized appreciation (depreciation), Net Gross Realized Losses Equity Securities Equity securities, Gross realized losses This item represents the gross loss realized on the sale of equity securities categorized neither as held-to-maturity nor trading securities. Impairment of Investments Equity Securities Equity securities, Other-than-temporary impairment losses The amount charged to income if the decline in fair value for equity securities is deemed to be other than temporary. Fair Values of Financial Instruments Textuals Abstract Fair Values of Financial Instruments (Textuals) [Abstract] Fixed Maturities and Equity Securities In Unrealized Loss Position [Member] Fixed Maturities And Equity Securities In Unrealized Loss Position. Increase Decrease In Deferred Policy Acquisition Cost Increase (decrease) in deferred policy acquisition cost The net change during the reporting period in the balance sheet value, excluding foreign currency translation effect, of capitalized sales costs that are associated with acquiring a new insurance customers. Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Disclosure Item Amounts [Domain] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, by Balance Sheet Grouping [Table] Fair Value [Member] Carrying Value [Member] Cumulative Effect Of Initial Adoption Of New Accounting Principle Net Of Tax Cumulative effect from adoption of new guidance on recognition of other-than-temporary impairments Cumulative effect of initial adoption of new accounting principle on beginning Retained Earnings and Accumulated Other Comprehensive Income, net of tax. This element can be used, generally, for the adjustment to Retained Earnings and Accumulated Other Comprehensive Income of a new accounting principle. Percentage Of Fair Value Amounts For Fixed Maturities Provided By Pricing Service Percentage of fair value amounts for fixed maturities provided by a pricing service Percentage of fair value amounts for fixed maturities provided by a pricing service. Fixed Maturities Total fixed maturities, Fair value This item represents total fixed maturities that are categorized as neither held-to-maturity nor trading. Such securities are reported at fair value; unrealized gains and losses of such securities are excluded from earnings and included in other comprehensive income. Total Fixed Maturities And Equity Securities Unrealized Appreciation Depreciation Net Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net The net excess or deficiency of the fair value of available for sale securities over or under its amortized cost which has not been recognized in earnings of the entity. Fixed Maturities Other Than Temporary Impairment Losses in Gross Unrealized Depreciation Fixed maturities other-than-temporary impairment losses in gross unrealized depreciation. Fixed maturities other-than-temporary impairment losses in gross unrealized depreciation Cumulative Credit Losses Recognized In Net Income Cumulative credit losses recognized in net income Cumulative credit-related losses, recognized in net income, related to fixed maturities held, for which a portion of their other-than-temporary impairment losses were recognized in other comprehensive income. Change in Income Tax Recoverable or Payable Change in Income Tax Recoverable or Payable Change in Income Tax Recoverable or Payable Change in Income Tax Recoverable or Payable. Accounting Pronouncements Not Yet Adopted [Text Block] Accounting Pronouncements Not Yet Adopted Description of accounting pronouncements not yet adopted. Accounting Pronouncements Not Yet Adopted [Abstract] Major Types of Debt and Equity Securities [Domain] Schedule of Available-for-sale Securities, Major Types of Debt and Equity Securities [Axis] Length of time in unrealized loss position [Axis] Length of time in unrealized loss position Axis Length of time in unrealized loss position [Domain] Length of time in unrealized loss position Domain Deferred Tax Assets (Liabilities), Net Deferred Tax Assets (Liabilities), Net, Total Deferred Income Tax Net Deferred Tax Assets Liabilities Deferred Income Tax For entities that net deferred tax assets and tax liabilities, represents the unclassified net amount of deferred tax assets and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities. Amortized cost and fair value of fixed maturities by contractual maturity [Abstract] Amortized cost and fair value of fixed maturities by contractual maturity [Abstract] Fair value and gross unrealized depreciation of investments in an unrealized loss position [Abstract] Change in unrealized appreciation or depreciation of investments carried at fair value [Abstract] Components Of Unrealized Appreciation Or Depreciation Of Investments Abstract Components of unrealized appreciation or depreciation of investments [Abstract] Losses and Expenses [Abstract] Losses and Expenses Segment Reporting Information [Line Items]