Document And Entity Information Abstract Document And Entity Information [Abstract] Statement [Table] Statement [Line Items] Grants, Number of Shares Document Type Document Period End Date Amendment Flag Document Fiscal Year Focus Document Fiscal Period Focus Current Fiscal Year End Date Entity Central Index Key Entity Filer Category Entity Registrant Name Entity Common Stock, Shares Outstanding Entity Public Float Trading Symbol Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Consolidated Balance Sheets [Abstract] Assets Available For Sale Securities Debt Securities Fixed maturity securities available for sale, at fair value (amortized cost-$334,115 in 2011 and $318,190 in 2010) Fair Value Total, Fair value Fixed maturity securities available for sale, at fair value (amortized cost-$10,123,429 in 2011 and $10,009,320 in 2010) Available For Sale Securities Equity Securities Equity securities available for sale, at fair value (amortized cost-$9,929 in 2011 and $4,638 in 2010 0 316,832 Equity securities available for sale, at fair value (amortized cost-$0 in 2011) Total equity securities, Fair Value Equity securities available for sale, at fair value (cost-$357,411 in 2011 and $452,648 in 2010) Commercial mortgage loans on real estate, at amortized cost Net commercial mortgage loans Commercial mortgage loans on real estate, Carrying Value Mortgage Loans on Real Estate, Commercial and Consumer, Net, Total Commercial mortgage loans on real estate, at amortized cost Policy loans Policy loans, Carrying Value Other Short Term Investments Short-term investments Collateral Held Under Securities Lending Collateral Held Under Securities Lending Collateral held under securities agreements Other investments Other Investments, Total Total investments Total investments Cash and cash equivalents Cash and cash equivalents at end of period Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value, Total Premiums and accounts receivable, net Total Premiums and accounts receivable, net Reinsurance recoverables Net of reinsurance, ending balance Net of reinsurance, beginning balance Net reinsurance recoverable Accrued investment income Accrued Investment Income Receivable, Total Deferred Policy Acquisition Costs Ending balance Beginning balance Deferred Policy Acquisition Costs, Total Deferred acquisition costs Property and equipment, at cost less accumulated depreciation Property, Plant and Equipment, Net, Ending Balance Property, Plant and Equipment, Net, Beginning Balance Property, Plant and Equipment, Net, Total Property and equipment, at cost less accumulated depreciation Deferred Tax Assets Net Deferred income taxes, net Deferred income taxes, net Net deferred income tax asset Deferred tax asset Goodwill Goodwill, Ending Balance Goodwill, Beginning Balance Goodwill, carrying amount Goodwill, Total Goodwill Value of business acquired Ending balance Beginning balance Intangible Assets, Net (Excluding Goodwill) Intangible Assets, Net (Excluding Goodwill), Total Other intangible assets, net Other assets Other Assets, Total Assets held in separate accounts Total assets Total assets Total assets Liabilities Future policy benefits and expenses Liability for Future Policy Benefits, Ending Balance Liability for Future Policy Benefits, Beginning Balance Future Policy Benefits and Expenses Liability for Future Policy Benefits, Total Unearned premiums Unearned Premiums Unearned Premiums, Total Claims and benefits payable Commissions payable Reinsurance balances payable Gross of reinsurance, ending balance Gross of reinsurance, beginning balance Funds withheld under reinsurance Funds held under reinsurance, Carrying Value The obligations arising from a disposal of business utilizing reinsurance. The gain on the disposals was deferred since the form of sale did not discharge the company's primary liability to insured's. Deferred gain on disposal of businesses Obligation Under Securities Lending Obligation Under Securities Lending Obligation under securities lending Obligation under securities agreements Accounts payable and other liabilities Accounts Payable and Accrued Liabilities, Total Deferred income taxes, net Net deferred income tax liability Deferred income taxes, net Net deferred income tax liability Tax payable Accrued Income Taxes, Total Unsecured Debt Debt Unsecured Debt, Total Debt, Carrying Value Shares Subject To Mandatory Redemption Settlement Terms Amount Mandatorily redeemable preferred stock Mandatorily redeemable preferred stocks, Carrying Value Shares Subject to Mandatory Redemption, Settlement Terms, Amount, Total Mandatorily redeemable preferred stock Liabilities related to separate accounts Liabilities, Total Total liabilities Commitments and contingencies -Note 14) Commitments and Contingencies Commitments and contingencies (Note 14) Commitments and contingencies (Note 25) Stockholders' equity Common stock, par value $0.01 per share, 800,000,000 shares authorized, 0 and 116,648,714 shares outstanding at December 31, 2010 and 2009, respectively Common stock, par value $0.01 per share, 800,000,000 shares authorized, 88,524,374 and 102,000,371 shares outstanding at December 31, 2011 and 2010, respectively Common Stock, Value, Issued, Ending Balance Common Stock, Value, Issued, Beginning Balance Common stock, par value $0.01 per share, 800,000,000 shares authorized, 0 and 102,000,371 shares outstanding at March 31, 2011 and December 31, 2010, respectively Common Stock, Value, Issued, Total Common stock, par value $0.01 per share, 800,000,000 shares authorized, 88,524,374 and 102,000,371 shares outstanding at December 31, 2011 and 2010, respectively Additional Paid In Capital Common Stock Additional Paid in Capital, Common Stock, Ending Balance Additional Paid in Capital, Common Stock, Beginning Balance Additional paid-in capital Additional paid-in capital Retained Earnings Accumulated Deficit Retained earnings Retained Earnings (Accumulated Deficit), Ending Balance Retained Earnings (Accumulated Deficit), Beginning Balance Retained earnings Retained Earnings (Accumulated Deficit), Total Undistributed earnings Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated other comprehensive income, Ending balance Accumulated other comprehensive income, Beginning balance Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax, Total Accumulated other comprehensive income Treasury Stock, Value Treasury stock, at cost; 57,433,178 and 43,344,638 shares at December 31, 2011 and 2010, respectively Treasury stock, at cost; 57,433,178 and 43,344,638 shares at December 31, 2011 and 2010, respectively Treasury Stock, Value, Ending Balance Treasury Stock, Value, Beginning Balance Treasury stock, at cost; 43,344,638 and 28,119,993 shares at December 31, 2010 and 2009, respectively " Treasury stock, at cost; 38,849,679 and 28,119,993 at September 30, 2010 and December 31, 2009, respectively Stockholder's equity Balance Balance Total stockholders' equity Total stockholders' equity Liabilites and stockholders' equity Total liabilities and stockholders' equity Available-for-sale Securities, Amortized Cost Fixed maturity securities available for sale, amortized cost Available-for-sale Securities, Amortized Cost Basis, Total Securities available for sale, amortized cost This item represents the total cost basis of all equity securities available-for-sale disclosed parenthetically. Equity Securities Available For Sale Cost Equity securities available for sale, cost Common stock, par value Common stock, shares authorized Shares authorized Common stock, shares outstanding Shares outstanding, ending Shares outstanding, beginning Treasury stock, shares Treasury Stock, Shares, Ending Balance Treasury Stock, Shares, Beginning Balance Consolidated Statements Of Operations [Abstract] Revenues Net earned premiums and other considerations Net earned premiums and other considerations Net earned premiums and other considerations Premiums Earned, Net, Total Net earned premiums Net investment income Net investment income Net investment income This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain or loss of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain or loss which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains or losses realized during the period from the sale of investments accounted for under the cost method of accounting. Net Realized Gains Losses On Investments Excluding Other Than Temporary Impairment Losses Net realized gains (losses) on investments, excluding other-than-temporary impairment losses Net realized gains (losses) on investments, excluding other-than-temporary impairment losses Net realized gains (losses) related to sales and other The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income. Total other-than-temporary impairment losses Total other-than-temporary impairment losses The amount of other than temporary impairment loss on a debt security, categorized as either Available-for-sale or Held-to-maturity, related to factors other than credit losses when the entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis. This amount, which includes the portion attributable to the noncontrolling interest, if any, is deducted from the total impairment losses of investments (before taxes) presented on the income statement; this amount is also referred to as the amount incurred by the reporting entity or the consolidated entity. Portion Of Loss Gain Recognized In Other Comprehensive Income Before Taxes Portion of gain recognized in other comprehensive income, before taxes Portion of gain recognized in other comprehensive income, before taxes Portion of net (gain) loss recognized in other comprehensive income, before taxes The amount of other-than-temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis. Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net Available For Sale Securities Net other-than-temporary impairment losses recognized in earnings Net other-than-temporary impairment losses recognized in earnings Net other-than-temporary impairment losses recognized in earnings Net other-than-temporary impairment losses recognized in earnings Net realized losses related to other-than-temporary impairments The amount of gain (amortization) recognized during the period on the deferred gain on disposal of businesses utilizing reinsurance. Amortization of deferred gain on disposal of businesses Amortization of deferred gain on disposal of businesses Fees and other income Fees and other income Other Income, Total Total revenues Total revenues Total revenues Revenues Benefits, losses and expenses Policyholder benefits Policyholder benefits Net policyholder benefits Represents the total amortization expense with respect to capitalized deferred acquisition cost ("DAC") and value of business acquired ("VOBA") reflected in the results of operation for the period. DAC typically includes the nature of costs incurred in an acquisition, which primarily consists of commission, policy issuance costs and certain direct marketing expenses. VOBA represents the Company's present value of future profits embedded in acquired businesses (i.e. business combinations or assumption reinsurance). Amortization of deferred acquisition costs and value of business acquired Amortization of deferred acquisition costs and value of business acquired Underwriting, general and administrative expenses Underwriting, general and administrative expenses Selling, General and Administrative Expense, Total Interest expense Interest expense Interest Expense, Total Goodwill, Impairment Loss Goodwill impairment Goodwill impairment charge Implied fair value of goodwill Goodwill impairment Total benefits, losses and expenses Total benefits, losses and expenses Total benefits, losses and expenses Income before provision for income taxes Income before benefit for income taxes Income before provision for income taxes Income (loss) before provision for income taxes Provision for income taxes Provision (benefit) for income taxes Total income tax expense Benefit for income taxes Net income Net income Net income Net income (loss) Earnings Per Common Share [Abstract] Earnings per share Basic Net income (loss), Basic per share Net income - Basic Earnings Per Share, Basic, Total Net income Diluted Net income (loss), Diluted per share Net income - Diluted Earnings Per Share, Diluted, Total Net income Dividends per share Share data: Share data: Weighted average shares outstanding used in basic per share calculations Weighted average shares outstanding used in basic earnings per share calculations Weighted Average Number of Shares Outstanding, Basic, Total Plus: Dilutive securities Weighted average shares used in diluted per share calculations Weighted average shares used in diluted per share calculations Weighted average shares used in diluted earnings per share calculations Weighted average shares used in diluted per share calculations Statement of Income and Comprehensive Income [Abstract] Other comprehensive income (loss): Other comprehensive income: Net change in unrealized gains on securities, net of taxes Unrealized (losses) gains on securities, Activity Other Comprehensive Income, Available-for-sale Securities Adjustment, Net of Tax, Total Change in unrealized losses on securities, net of taxes of $(109,263) and $(353,445), respectively The after-tax amount of other than temporary impairment loss on a debt security, categorized as Available-for-sale, related to factors other than credit losses when the entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis. This amount of other than temporary losses on Available-for-sale Securities, net of applicable taxes, includes the portion attributable to the noncontrolling interest, if any; this amount is also referred to as the amount incurred by the reporting entity or the consolidated entity. Net Change In Other Than Temporary Impairment Gains Recognized In Other Comprehensive Income Net Of Taxes Net change in other-than-temporary impairment gains recognized in other comprehensive income, net of taxes Change in other-than-temporary impairment gains recognized in other comprehensive income, net of taxes of $(3,388) and $(7,556), respectively Net change in foreign currency translation, net of taxes Foreign currency translation adjustment, Activity Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total Changes in foreign currency translation, net of taxes of $(6,803) and $(17,551), respectively Amortization of pension and postretirement unrecognized net periodic benefit cost and change in funded status, net of taxes of $7,303 and $6,579, respectively Pension under-funding, Activity Other Comprehensive Income, Defined Benefit Plans Adjustment, Net of Tax, Total Amortization of pension and postretirement unrecognized net periodic benefit cost, net of taxes Other Comprehensive Income (Loss), Net of Tax, Total Other comprehensive income, Activity Total other comprehensive income Total other comprehensive income Comprehensive Income, Net of Tax, Attributable to Parent, Total Total comprehensive income Total comprehensive income Net change in unrealized gains on securities, tax Net change in unrealized gains on securities, taxes Other Comprehensive Income, Available-for-sale Securities, Tax, Total The tax effect related to other than temporary impairment loss on a debt security, categorized as Available-for-sale, related to factors other than credit losses when the entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis. This amount is the portion of the tax effect on other than temporary losses related to investments in debt securities categorized as Available-for-sale which includes the portion attributable to the noncontrolling interest, if any; this amount is also referred to as the amount incurred by the reporting entity or the consolidated entity. Net Change In Other Than Temporary Impairment Gains Recognized In Other Comprehensive Income Tax Net change in other-than-temporary impairment gains recognized in other comprehensive income, taxes Net change in foreign currency translation, taxes Amortization of pension and postretirement unrecognized net periodic benefit cost, tax Amortization of pension and postretirement unrecognized net periodic benefit cost, taxes Other Comprehensive Income, Defined Benefit Plans, Tax, Total Consolidated Statements Of Stockholders' Equity [Abstract] Statement, Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock [Member] Additional Paid In Capital [Member] Additional Paid-In Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Accumulated Other Comprehensive Income [Member] Accumulated Other Comprehensive Income [Member] Treasury Stock [Member] Treasury Stock [Member] Stock plan exercises Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures, Total The expense related to the fair value of stock based compensation that has been granted but is not yet fully vested during the period. Stock plan compensation expense Adjustments To Additional Paid In Capital Tax Effect From Share Based Compensation Change in tax benefit from share-based payment arrangements Dividends Cash Dividends Deduct dividends paid Dividends Dividends, Cash, Total Deduct dividends paid TreasuryStockValueAcquiredCostMethod Acquisition of common stock Acquisition of common stock Cumulative Effect Of Initial Adoption Of New Accounting Principles Cumulative Effect Of Initial Adoption Of New Accounting Principles Cumulative effect of change in accounting principles (Note 2) Consolidated Statement Of Cash Flows [Abstract] Operating activities Adjustments to reconcile net income to net cash provided by operating activities: Increase (Decrease) in Reinsurance Recoverable Change in reinsurance recoverable Change in reinsurance recoverable Change In Premiums And Accounts Receivable Change In Premiums And Accounts Receivable Change in premiums and accounts receivable Change In Deferred Acquisition Costs And Value Of Business Acquired Change In Deferred Acquisition Costs And Value Of Business Acquired Change in deferred acquisition costs and value of business acquired Change In Intangibles Change In Intangibles Change in intangible assets Increase (Decrease) in Accrued Investment Income Receivable Change in accrued investment income Change in accrued investment income Change In Insurance Policy Reserves And Expenses Change In Insurance Policy Reserves And Expenses Change in insurance policy reserves and expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Change in accounts payable and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities, Total Change In Commissions Payable Change In Commissions Payable Change in commissions payable Increase (Decrease) in Reinsurance Payables Change in reinsurance balances payable Increase (Decrease) in Funds Held under Reinsurance Agreements Change in funds held under reinsurance Change in funds held under reinsurance Increase (Decrease) in Trading Securities Change in securities classified as trading Change in securities classified as trading Increase (Decrease) in Trading Securities, Total Deferred Income Taxes and Tax Credits Change in income taxes Deferred Income Taxes and Tax Credits, Total Valuation Allowance, Deferred Tax Asset, Change in Amount Increase in valuation allowance related to deferred tax assets Change in tax valuation allowance Change Of Amortization Of Deferred Gain On Disposal Of Businesses Change Of Amortization Of Deferred Gain On Disposal Of Businesses Amortization of deferred gain on disposal of businesses Depreciation, Amortization and Accretion, Net Depreciation and amortization Depreciation, Amortization and Accretion, Net, Total Gain (Loss) on Sale of Investments Net realized (gains) losses on investments Gain (Loss) on Sale of Investments, Total Increase Decrease In Stock Based Compensation Expense Increase Decrease In Stock Based Compensation Expense Stock based compensation expense Change In Tax Benefit From Share-Based Payment Arrangements Change In Tax Benefit From Share-Based Payment Arrangements Change in tax benefit from share-based payment arrangements Impairment of Intangible Assets (Excluding Goodwill) Other intangible asset impairment Impairment charges Impairment of Intangible Assets (Excluding Goodwill), Total Other intangible assets Increase (Decrease) in Other Operating Assets Other Increase (Decrease) in Other Operating Assets, Total Other Net cash provided by operating activities Net cash provided by operating activities Net cash provided by operating activities Investing activities Sales of Investing Activities Sales of Abstract Sales of: Proceeds From Sale Of Available For Sale Securities Debt Fixed maturity securities available for sale Equity securities available for sale Equity securities available for sale Proceeds from Sale of Other Investments Other invested assets Property and equipment and other Property and equipment and other Proceeds from Sale of Property, Plant, and Equipment, Total [Sales of] Maturities Prepayments And Redemption Available For Sale Securities Debt Abstract Maturities Prepayments And Redemption Available For Sale Securities Debt Abstract Maturities, prepayments, and scheduled redemption of: Maturities, prepayments, and scheduled redemption of: Fixed maturity securities available for sale The cash inflow from the maturity (principal due), prepayment and call (request of early payment) of a loan financed by commercial mortgage payments on real estate. Proceeds from maturities, preparyments and calls of commercial mortgage loans on real estate Commercial mortgage loans on real estate Payments Of Investments [Abstract] Payments Of Investments Abstract Purchase of: Purchase of: Fixed maturity securities available for sale [Purchase of] Fixed maturity securities available for sale Equity securities available for sale [Purchase of] Equity securities available for sale The cash outflow for the purchase of commercial mortgage loans on real estate Payments to acquire commercial mortgage loans on real estate Commercial mortgage loans on real estate Commercial mortgage loans on real estate Payments to Acquire Other Investments Other invested assets Other invested assets Property and equipment and other [Purchase of] Property and equipment and other Payments to Acquire Property, Plant, and Equipment, Total [Purchase of] Subsidiary, net of cash transferred [Purchase of] Subsidiaries and warranty business, net of cash transferred (1) Subsidiaries and warranty business, net of cash transferred (1) Payments to Acquire Businesses, Net of Cash Acquired, Total Change in short-term investments Change in short-term investments Payments for (Proceeds from) Short-term Investments, Total The net change in the carrying amount of loans outstanding to policy and contract holders accounts during the reporting period. Change in policy loans The net change during the reporting period in the amount of cash that is reinvested. Change in collateral held under securities lending Change in collateral held/pledged under securities agreements Net cash (used in) provided by investing activities Net cash (used in) provided by investing activities Net cash (used in) provided by investing activities Net cash used in investing activities Financing activities The amount paid during the period, determined under the conditions specified in the contract, to the holder of mandatorily redeemable preferred stock as a result of the holder electing to redeem shares. Repayment of mandatorily redeemable preferred stock Repayment of mandatorily redeemable preferred stock Excess Tax Benefit From Share Based Compensation Financing Activities Change in tax benefit from share-based payment arrangements Change in tax benefit from share-based payment arrangements Acquisition of common stock Acquisition of common stock Dividends paid Dividends paid Payments of Dividends, Total Change in obligation under securities lending Change in obligation under securities agreements Increase (Decrease) in Receivables under Repurchase Agreements Change in receivables under securities loan agreements Change in receivables under securities loan agreements Increase (Decrease) in Borrowed Securities Change in obligations to return borrowed securities Change in obligations to return borrowed securities Net cash used in financing activities Net cash used in financing activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents, Total Change in cash and cash equivalents Change in cash and cash equivalents Supplemental information: Income Taxes Paid, Net Income taxes paid, net of refunds Income Taxes Paid, Net, Total Interest Paid, Net Interest paid on mandatorily redeemable preferred stock and debt Interest Paid, Net, Total Nature Of Operations Nature Of Operations [Abstract] Nature of Operations [Text Block] Nature Of Operations Summary Of Significant Accounting Policies [Abstract] Significant Accounting Policies [Text Block] Summary Of Significant Accounting Policies Business Combinations [Abstract] Business Combination Disclosure [Text Block] Business Combinations Investments [Abstract] This item represents the entire disclosure related to Investments which includes debt and equity securities by type, commercial mortgage loans on real estate, policy loans, short-term investments, collateral held under securities lending, other investments and cash and cash equivalents. A debt security represents a creditor relationship with an enterprise that is in the form of a security. Debt securities include, among other types, United States Government and government agencies and authorities, states, municipalities and political subdivisions, foreign governments, asset-backed, commercial mortgage-backed, residential mortgage-backed and corporate securities. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other types, common stock and certain non-redeemable preferred stocks. Commercial mortgage loans are loans collateralized by investments commercial real estate. Policy loans are amounts loaned to policyholders by the Company for the value of their life insurance as collateral in return for cash received. Short-term investments include all investment cash and short maturity investments. Collateral held under securities lending is cash received for securities loaned to other broker dealers typically used by such parties to cover short sales, that is reinvested in available-for-sale securities. Other investments consist primarily of investments in joint ventures, partnerships, invested assets associated with a modified coinsurance agreement and the Company's Assurant Investment Plan, the American Security Insurance Company Investment Plan and the Assurant Deferred Compensation Plan. Investments Text Block Investments Fair Value Disclosures [Abstract]