Document and Entity Information [Abstract] Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Document Fiscal Year Focus Document Fiscal Period Focus Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Reinsurance Recoverable Reinsurance Recoverable on Unpaid Losses and Loss Expenses Net Income (Loss) Attributable to Parent Net Income Net Income Earnings Per Share, Basic Basic earnings per share Basic Earnings Per Share, Diluted Diluted earnings per share Diluted Other Invested Assets Other Invested Assets This item represents other invested assets which include investments such as private equity limited partnerships carried at the Corporation's equity in the net assets of the partnerships and warrants reported at fair value. Federal and Foreign Income Tax Income Tax Expense (Benefit) Income Before Federal and Foreign Income Tax Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Cumulative Effects of Changes in Accounting Principles, Noncontrolling Interest Stockholders' Equity Attributable to Parent TOTAL SHAREHOLDERS' EQUITY Revenues Total Revenues Deferred Policy Acquisition Cost, Amortization Expense Amortization of Deferred Policy Acquisition Costs Long-term Debt Long term debt Long Term Debt Corporate Bond Securities [Member] Corporate bonds [Member] Investment Type [Axis] Deferred Policy Acquisition Costs Deferred Policy Acquisition Costs Foreign Government Debt [Member] Foreign government and government agency obligations [Member] Consolidated Balance Sheets [Abstract] Consolidated Statements of Income [Abstract] Consolidated Statements of Cash Flows [Abstract] Liabilities and Stockholders' Equity TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY Assets [Abstract] Assets [Abstract] Liabilities [Abstract] Liabilities [Abstract] Stockholders' Equity Attributable to Parent [Abstract] Shareholders' Equity [Abstract] Treasury Stock, at Cost - 106,131,522 and 99,519,509 Shares Treasury Stock, Value Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated Other Comprehensive Income Retained Earnings (Accumulated Deficit) Retained Earnings Additional Paid in Capital Paid-In Surplus Common Stock, Value, Issued Common Stock - $1 Par Value; 371,980,460 Shares Liabilities TOTAL LIABILITIES Other Liabilities Accrued Expenses and Other Liabilities Dividends Payable Dividend Payable to Shareholders Assets TOTAL ASSETS Other Assets Other Assets Investments TOTAL INVESTED ASSETS Equity securities, Fair Value Equity Securities (cost $1,261 and $1,264) Available-for-sale Securities, Equity Securities Equity securities Revenues [Abstract] Revenues [Abstract] Other Nonoperating Expense Other Expenses Investment Income, Investment Expense Investment Expenses Corporate Expenses The total amount of expenses incurred by the entity related to corporate activities, including interest expense. Corporate Expenses Gain (Loss) on Investments Realized Investment Gains, Net Total Realized Investment Gains, Net Realized investment gains, net Other Income Other Revenues Interest and Dividend Income, Operating Investment Income Common Stock, Par or Stated Value Per Share Common Stock, Par Value Common Stock, Shares, Issued Common Stock, Shares issued Net Cash Provided by (Used in) Operating Activities [Abstract] Cash Flows from Operating Activities [Abstract] Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities [Abstract] Net Cash Provided by (Used in) Investing Activities [Abstract] Cash Flows from Investing Activities [Abstract] Net Cash Provided by (Used in) Financing Activities [Abstract] Cash Flows from Financing Activities [Abstract] Net Cash Provided by (Used in) Financing Activities Net Cash Used in Financing Activities Payments of Dividends, Common Stock Dividends Paid to Shareholders Payments for Repurchase of Common Stock Repurchase of Shares Proceeds from Stock Plans Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans Net Cash Provided by (Used in) Investing Activities Net Cash Provided by (Used in) Investing Activities Payments for (Proceeds from) Short-term Investments Decrease (Increase) in Short Term Investments, Net Payments to Acquire Available-for-sale Securities, Debt Purchases of Fixed Maturities Proceeds from Sale of Available-for-sale Securities, Equity Proceeds from Sales of Equity Securities Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities Proceeds from Fixed Maturities - Maturities, Calls and Redemptions Proceeds from Fixed Maturities - Sales Proceeds from Sale of Available-for-sale Securities, Debt Net Cash Provided by (Used in) Operating Activities Net Cash Provided by Operating Activities Increase (Decrease) in Other Operating Assets and Liabilities, Net Other, Net Premiums Earned, Net, Property and Casualty Net premiums earned Premiums Earned Other Short-term Investments Short term investments Short Term Investments Liability for Claims and Claims Adjustment Expense, Property Casualty Liability Unpaid Losses and Loss Expenses Incurred Claims, Property, Casualty and Liability Losses and Loss Expenses Unearned Premiums Unearned Premiums Other Underwriting Expense Other Insurance Operating Costs and Expenses Tax Exempt, Cost Tax exempt, Amortized Cost This item represents the amortized cost basis of tax exempt debt securities that are categorized as neither held-to-maturity nor trading. Tax Exempt, Gross Unrealized Appreciation 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 Depreciation 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 Tax exempt, Fair Value Tax exempt, Fair value 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, Cost Taxable, Amortized Cost This item represents the amortized cost basis of taxable debt securities that are categorized as neither held-to-maturity nor trading. Taxable, Gross Unrealized Appreciation 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 Depreciation 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 Taxable, Fair Value Taxable, Fair value 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. Fixed Maturities Gross Unrealized Appreciation Total fixed maturities, Gross Unrealized Appreciation 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. 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 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 Depreciation Equity securities, Gross Unrealized Depreciation 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. Residential Mortgage Backed Securities [Member] Residential mortgage-backed securities [Member] Commercial Mortgage-Backed Securities [Member] Commercial mortgage-backed securities [Member] Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis Due in one year or less, Amortized cost Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value Due in one year or less, Fair value Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Amortized Cost Basis Due after one year through five years, Amortized cost Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value Due after one year through five years, Fair value Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Amortized Cost Basis Due after five years through ten years, Amortized cost Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value Due after five years through ten years, Fair value Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Amortized Cost Basis Due after ten years, Amortized cost Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Fair Value Due after ten years, Fair value Fixed Maturities and Equity Securities, Unrealized Appreciation (Depreciation), Net of Tax 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. Deferred Income Tax Asset 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. Equity Securities, Unrealized Appreciation (depreciation), Net 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. Fixed Maturities, Unrealized Appreciation (depreciation), Net 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. Schedule of Available-for-sale Securities [Table] Major Types of Debt and Equity Securities [Domain] Schedule of Available-for-sale Securities [Line Items] Fixed Maturities Change in Unrealized Appreciation or Depreciation Change in unrealized appreciation 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 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. Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss) Change in unrealized appreciation of fixed maturities and equity securities Available-for-sale Securities, Income Tax Expense on Change in Unrealized Holding Gain or Loss Deferred income tax(credit) Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax Total change in unrealized appreciation of fixed maturities and equity securities, Net of tax 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 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. 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. Other Invested Assets Gain Loss 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. Net Investment Income, Insurance Entity Investment income 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. Earnings Per Share [Text Block] Earnings Per Share Weighted Average Number of Shares Outstanding, Basic Weighted average shares outstanding Weighted Average Number of Shares Outstanding, Diluted Weighted average shares and potential shares assumed outstanding for computing diluted earnings per share Earnings Per Share, Basic [Abstract] Basic earnings per share: [Abstract] Earnings Per Share, Diluted [Abstract] Diluted earnings per share: [Abstract] Earnings Per Share [Abstract] Net Income Per Share [Abstract] Segment Reporting Disclosure [Text Block] Segments Information Property and Casualty Insurance [Member] Property and casualty insurance [Member] This element represents property and casualty insurance businesses. Corporate and Other Revenues Corporate and other revenues Represents revenues related to non-insurance companies, before realized investment gains or losses. Property and Casualty Insurance Income before Taxes and Corporate Companies Total property and casualty insurance 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). 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). Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information [Line Items] Level 1 [Member] Level 1 [Member] Level 2 [Member] Level 2 [Member] Level 3 [Member] Level 3 [Member] Fair Value, by Balance Sheet Grouping [Text Block] Carrying values and fair values of financial instruments Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, Disclosure Item Amounts [Domain] Carrying Value [Member] Carrying Value [Member] Fair Value [Member] Fair Value [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Carrying Values and Fair Values of Financial Instruments [Abstract] Carrying values and fair values of financial instruments [Abstract] TOTAL INVESTED ASSETS Cash Cash at End of Period Cash at Beginning of Year Cash Assets TOTAL 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 Stockholders' Equity Attributable to Parent TOTAL SHAREHOLDERS' EQUITY Liabilities TOTAL 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, Par Value Treasury Stock, Shares Treasury Stock, at Cost - 16,279,184 Shares in 2008 Accumulated Other Comprehensive Income Common Stock, Shares, Outstanding Interest And Dividend Income Operating Investment Income Other Income Other Revenues Revenues Total Revenues Gain (Loss) on Investments Total Realized Gains (Losses), Net Realized investment gains (losses), net 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 Net Income Earnings Per Share, Basic Basic Earnings Per Share, Diluted Diluted Investment Expenses Comprehensive Income, Net of Tax, Attributable to Parent Comprehensive Income Net Income Net Cash Provided by (Used in) Operating Activities Net Cash Provided by Operating Activities Increase decrease in other operating capital net Amortization of Premiums and Discounts on Fixed Maturities Amortization of Premiums and Discounts on Fixed Maturities Decrease in Unearned Premiums, Net Increase in Unearned Premiums, Net Decrease in Premiums Receivable Increase in Premiums Receivable Net Cash Provided by (Used in) Investing Activities Net Cash Used in Investing Activities Net Cash Provided by (Used in) Financing Activities Net Cash Used in Financing Activities Purchases of Equity Securities Purchases of Equity Securities Other Expenses Dividends Paid to Shareholders Repurchase of Shares Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans Payments to Acquire Property, Plant, and Equipment Purchases of Property and Equipment, Net Segments Information Purchases of Fixed Maturities Shareholders' Equity [Abstract] Liabilities [Abstract] Liabilities [Abstract] Assets [Abstract] Assets [Abstract] Earnings Per Share [Abstract] Revenues [Abstract] Revenues [Abstract] Other Comprehensive Income (Loss), Net of Tax [Abstract] Other Comprehensive Income (Loss), Net of Tax [Abstract] Cash Flows from Investing Activities [Abstract] 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 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 Proceeds from Sales of Equity Securities Proceeds from Sale of Available-for-sale Securities, Equity Federal and Foreign Income Tax Income Tax Expense (Benefit) Long Term Debt Long-term Debt Retained Earnings Retained Earnings (Accumulated Deficit) Accumulated Other Comprehensive Income (Loss), Net of Tax Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans Liability for Claims and Claims Adjustment Expense, Property Casualty Liability Paid-In Surplus Additional Paid in Capital Payments for (Proceeds from) Limited Partnership Investments in Other Invested Assets, Net 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 Change in net receivable or payable from security transactions not settled. Premiums Earned, Net, Property and Casualty Premiums Earned, Net, Property and Casualty, Total Premiums Earned Investments Increase in Unpaid Losses and Loss Expenses, Net Increase (Decrease) in Property and Casualty Insurance Liabilities Common Stock, Shares Issued Treasury Stock, Shares Accrued Investment Income Premiums Receivable Reinsurance Recoverable on Unpaid Losses and Loss Expenses Prepaid Reinsurance Premiums Deferred Policy Acquisition Costs Goodwill Unearned Premiums Cash Flows from Operating Activities [Abstract] Cash Flows from Investing Activities [Abstract] Short Term Investments Losses and Loss Expenses Amortization of Deferred Policy Acquisition Costs Other Insurance Operating Costs and Expenses Investment Expenses Other Expenses Net Income Per Share [Abstract] Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities [Abstract] Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Cash Flows from Financing Activities [Abstract] Common Stock, Par Value Total Realized Gains (Losses), Net Total Other-Than-Temporary Impairment Losses on Investments Earnings Per Share Earnings Per Share [Text Block] Dividend Payable to Shareholders Dividends Payable Segments Information Losses and Expenses [Abstract] Losses and Expenses [Abstract] Consolidated Statements of Comprehensive Income [Abstract] Increase Decrease In Funds Held Under Reinsurance Agreements Increase (Decrease) in Funds Held Under Deposit Contracts US Government and Government Agencies and Authorities [Member] U.S. Government and government agency and authority obligations [Member] Fair Value Disclosures [Text Block] Fair Values of Financial Instruments Amortized Cost and Fair Value of Invested Assets [Abstract] Amortized cost and fair value of fixed maturities and equity securities [Abstract] Gross Gain Loss OTTI Equity Securities Total equity securities The gross realized gain or loss, net, for equity securities included in earnings for the period. Personal Lines [Member] Personal insurance [Member] Commercial Lines [Member] Commercial insurance [Member] Income (Loss) Before Income Tax [Abstract] Income (loss) before income tax [Abstract] Gross Gain Loss OTTI Fixed Maturities Total fixed maturities The gross realized gain or loss, net, for fixed maturities included in earnings for the period. Commitments and Contingencies Disclosure [Text Block] Contingent Liabilities Common Stock, Dividends, Per Share, Declared Dividends Declared Per Share Tax Exempt [Member] Tax Exempt [Member] This element provides types of tax-exempt debt securities that are categorized as neither held-to-maturity nor trading. Taxable [Member] Taxable [Member] This element provides types of taxable debt securities that are categorized as neither held-to-maturity nor trading. Schedule of Fair Value of Separate Accounts by Major Category of Investment [Axis] Schedule of Fair Value of Separate Accounts by Major Category of Investment, Category [Domain] Fixed Maturities [Member] Fixed Maturities [Member] Equity Securities [Member] Equity securities [Member] Investment securities, Continuous unrealized loss position, Less than twelve months, Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Investment securities, Continuous unrealized loss position, Twelve months or longer, Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Investment securities, Continuous unrealized loss position, Fair Value, Total Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Fair value and gross unrealized depreciation of investments in an unrealized loss position [Abstract] Fair value and gross unrealized depreciation of investments in an unrealized loss position [Abstract] Increase (Decrease) in Deferred Policy Acquisition Costs Increase in deferred policy acquisition costs Contingent Liabilities (Note 6) Commitments and Contingencies Total fixed maturities, Fair Value Fixed Maturities (cost $34,975 and $34,762) Available-for-sale Securities, Debt Securities Fixed maturities Specialty Insurance [Member] 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 coverage's and surety. Investment Type Categorization [Domain] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Statement, Business Segments [Axis] Segment [Domain] Invested Assets [Abstract] Contingent Liabilities [Abstract] Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Amortized cost and fair value of fixed maturities and equity securities Investments Classified by Contractual Maturity Date [Table Text Block] Fair value and amortized cost of fixed maturities by contractual maturity Unrealized Gain (Loss) on Investments [Table Text Block] Components of unrealized appreciation or depreciation of investments Schedule of Unrealized Loss on Investments [Table Text Block] Fair value and gross unrealized depreciation of investments in an unrealized loss position Change in Unrealized Appreciation or Depreciation of Investments Carried at Fair Value [Table 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. Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Computation of basic and diluted earnings per share Cash, Period Increase (Decrease) Net Increase in Cash Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block] Fair values of financial instruments categorized based upon the lowest level of input Revenues and income before income tax of each operating segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Total fixed maturities, Amortized Cost Available-for-sale Debt Securities, Amortized Cost Basis Fixed Maturities, cost Equity Securities, Amortized Cost Available-for-sale Equity Securities, Amortized Cost Basis Equity Securities, cost Components of unrealized appreciation or depreciation of investments [Abstract] Components of unrealized appreciation or depreciation of investments [Abstract] Available-for-sale Securities, Gross Unrealized Gain (Loss) Total fixed maturities and equity securities, Unrealized appreciation (depreciation), Net Available For Sale Securities Change In Net Unrealized Holding Gain Loss Net Of Tax [Abstract] Change in unrealized appreciation or depreciation of investments carried at fair value [Abstract] Marketable Securities, Realized Gain (Loss) [Abstract] Realized investment gains and losses [Abstract] Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract] Fair values of financial instruments categorized based upon the lowest level of input [Abstract] Realized Investment Gains (Losses) [Abstract] Realized Investment Gains (Losses), Net [Abstract] Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), before Tax, Including Portion Attributable to Noncontrolling Interest, Available-for-sale Securities Other-Than-Temporary Impairment Losses on Investments Recognized in Other Comprehensive Income Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments Other Realized Investment Gains, Net Realized Gain (Loss) on Investments [Table Text Block] Realized investment gains and losses Marketable Securities Total fixed maturities and equity securities, Fair value Depreciation Depreciation Other Income Charges Other income Reflects the sum of all other income and charges recognized by the entity in the period not otherwise specified separately. Change in Unrealized Other than Temporary Impairment Losses on Investments Change in Unrealized Other-Than-Temporary Impairment Losses on Investments This item represents the change in 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. Adoption of New Accounting Pronouncements [Abstract] Segments Information [Abstract] Fair Values of Financial Instruments [Abstract] Fair Value By Asset Class [Axis] Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain] Fair Value by Asset Class [Axis] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Class [Domain] Losses and Expenses Total Losses and Expenses The amount of losses and expenses recognized during the period. Fair Value and Amortized Cost of Fixed Maturities by Contractual Maturity [Abstract] Fair value and amortized cost of fixed maturities by contractual maturity [Abstract] Approximate Number of Individual Fixed Maturity and Equity Securities in Unrealized Loss Position Approximate number of individual fixed maturity security and equity securities which were in an unrealized loss position. Approximate number of individual fixed maturity and equity securities in unrealized loss position Approximate Number of Individual Fixed Maturities in Unrealized Loss Position Approximate number of individual fixed maturities which were in an unrealized loss position. Approximate number of individual fixed maturities in unrealized loss position Premiums Earned from Property and Casualty 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 Property and Casualty Reinsurance Assumed Premiums earned related to 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. Property and Casualty Insurance Underwriting Income (Loss) Amount of underwriting income (loss) for the reportable property and casualty insurance 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. Insurance underwriting income Property and Casualty Reinsurance Assumed Underwriting Income Amount of underwriting income (loss) for the property and casualty insurance 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. Reinsurance assumed underwriting income Property and Casualty Underwriting Income Before Deferred Policy Acquisition Costs Underwriting income before deferred policy acquisition costs 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. Property and Casualty 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. Deferred Income Tax Liability Deferred Income Tax Represents the net amount of deferred tax liabilities, after netting deferred tax assets and deferred tax liabilities, as of the balance sheet date. Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value Taxable, Fair value Taxable, Amortized cost Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] General General [Abstract] Available for Sale Debt and Equity Securities Disclosure [Text Block] Invested Assets Disclosure related to invested assets and related income. Adoption of New Accounting Pronouncements (Textual) [Abstract] Adoption of New Accounting Pronouncements (Textual) [Abstract] Adoption of new accounting pronouncements. Decrease in Deferred Policy Acquisition Costs Due to Adoption of New Accounting Guidance Decrease in deferred policy acquisition costs due to the adoption of new accounting guidance The decrease in deferred policy acquisition costs due to the adoption of new accounting guidance related to the accounting for costs associated with acquiring or renewing insurance contracts. Decrease in Deferred Income Tax Liabilities Due to Adoption of New Accounting Guidance Decrease in deferred income tax liabilities due to the adoption of new accounting guidance The decrease in deferred income tax liabilities due to the adoption of new accounting guidance related to the accounting for costs associated with acquiring or renewing insurance contracts. Decrease in Shareholders Equity Due to Adoption of New Accounting Guidance Decrease in shareholders' equity due to the adoption of new accounting guidance The decrease in shareholders' equity due to the adoption of new accounting guidance related to the accounting for costs associated with acquiring or renewing insurance contracts. Adoption of New Accounting Pronouncements Disclosure [Text Block] Adoption of New Accounting Pronouncements Adoption of new accounting pronouncements. 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 pricing service. Investment securities, Continuous unrealized loss position, Less than twelve months, Gross Unrealized Depreciation Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses Investment securities, Continuous unrealized loss position, Twelve months or longer, Gross Unrealized Depreciation Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses Investment securities, Continuous unrealized loss position, Gross Unrealized Depreciation, Total Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Change in Unrealized Appreciation of Investments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Foreign Currency Translation Gains (Losses) Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Amortization of Net Actuarial Loss and Prior Service Cost Included in Net Postretirement Benefit Costs Other Comprehensive Income (Loss), Net of Tax Total Other Comprehensive Income, Net of Tax Change in Income Tax Payable or Recoverable Change in Income Tax Payable or Recoverable Change in income tax payable or recoverable. 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. Major Types of Debt and Equity Securities [Axis] Fair Values of Financial Instruments (Textual) [Abstract] Fair Values of Financial Instruments. Fair Values of Financial Instruments (Textual) [Abstract] Invested Assets (Textual) [Abstract] Invested assets. Invested Assets (Textual) [Abstract] Available for Sale Securities Debt Maturities Excluding Mortgage Backed Securities Fair Value Subtotal fixed maturities, Fair value Available for sale securities debt maturities excluding mortgage backed securities fair value. Available for Sale Securities Debt Maturities Excluding Mortgage Backed Securities Amortized Cost Subtotal fixed maturities, Amortized cost Available for sale securities debt maturities excluding mortgage backed securities. Incremental Common Shares Attributable to Share-based Payment Arrangements Additional shares from assumed issuance of shares under stock-based compensation awards