Investments [Abstract] Schedule of Held-to-maturity Securities [Table] Schedule of Held-to-maturity Securities [Table] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Japan government and agencies Foreign Government Debt Securities [Member] Municipalities Municipal Bonds [Member] Mortgage- and asset-backed securities Asset-backed Securities [Member] Public utilities Public Utility, Bonds [Member] Sovereign and supranational Sovereign Debt [Member] Banks/financial institutions Banks And Financial Institutions [Member] Banks and Financial Institutions Other corporate Corporate Debt Securities [Member] Currency [Axis] Currency [Axis] All Currencies [Domain] All Currencies [Domain] Yen-denominated Japan, Yen Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Fixed maturities Fixed Maturities [Member] Schedule of Held-to-maturity Securities [Line Items] Schedule of Held-to-maturity Securities [Line Items] Securities held to maturity, fixed maturities, amortized cost Held-to-maturity Securities Gross Unrealized Gains Held-to-maturity Securities, Accumulated Unrecognized Holding Gain Gross Unrealized Losses Held-to-maturity Securities, Accumulated Unrecognized Holding Loss Fair Value Held-to-maturity Securities, Fair Value Segment Reporting [Abstract] BUSINESS SEGMENT INFORMATION Segment Reporting Disclosure [Text Block] INVESTMENTS Investment [Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosure [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Japanese Pension Plan Foreign Pension Plan [Member] U.S. Pension Plan United States Pension Plan of US Entity [Member] Other Postretirement Benefit Plans, Defined Benefit Other Postretirement Benefit Plan [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Amortization of net actuarial loss Defined Benefit Plan, Amortization of Gains (Losses) Amortization of prior service cost (credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Net periodic (benefit) cost Defined Benefit Plan, Net Periodic Benefit Cost Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Reinsurance Disclosures [Abstract] REINSURANCE Reinsurance [Text Block] Fair Value Disclosures [Abstract] Fair Value Inputs, Assets, Quantitative Information [Table] Fair Value Inputs, Assets, Quantitative Information [Table] Dollar-denominated United States of America, Dollars Fair Value, Unobservable Input Type [Axis] Fair Value, Unobservable Input Type [Axis] Fair Value, Unobservable Input Type [Axis] Fair Value, Unobservable Input Type [Domain] Fair Value, Unobservable Input Type [Domain] Fair Value, Unobservable Input Type [Domain] Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), CDS Spreads and Foreign Exchange Rates [Member] Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spread Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and CDS Spreads [Member] Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY), and Foreign Exchange Rates Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] Fair Value, Unobservable Input, Interest Rates (USD), interest rates (JPY), and Foreign Exchange Rates [Member] Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate Fair value, unobservable input, base correlation, CDS spreads, recovery rate [Member] Fair value, unobservable input, base correlation, CDS spreads, recovery rate [Member] Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Derivative Contract Type [Domain] Derivative Contract [Domain] Foreign currency swaps Currency Swap [Member] Credit default swaps Credit Default Swap [Member] Perpetual securities Perpetual Securities [Member] Perpetual Securities Equity securities Equity Securities [Member] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Assets Assets [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Lower Limit Minimum [Member] Upper Limit Maximum [Member] Weighted Average Weighted Average [Member] Valuation Technique [Axis] Valuation Technique [Axis] Valuation Technique [Domain] Valuation Technique [Domain] Consensus pricing valuation technique Consensus Pricing Valuation Technique [Member] Consensus Pricing Valuation Technique [Member] Net asset value valuation technique Net Asset Value Valuation Technique [Member] Net Asset Value Valuation Technique [Member] Discounted cash flow valuation technique Discounted cash flow valuation technique [Member] Discounted Cash Flow Valuation Technique [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 3 Fair Value, Inputs, Level 3 [Member] Fair Value Inputs, Assets, Quantitative Information [Line Items] Fair Value Inputs, Assets, Quantitative Information [Line Items] Available-for-sale Securities Available-for-sale Securities Asset derivatives Derivative Asset Assets, fair value Assets, Fair Value Disclosure Fair Value Inputs, Offered Quotes Fair Value Inputs, Offered Quotes Fair Value Inputs, Discount Rate Fair Value Inputs, Discount Rate Fair Value Inputs, Entity Credit Risk Fair Value Inputs, Entity Credit Risk Fair Value Inputs, Recovery Rate Fair Value Inputs, Recovery Rate Fair Value Inputs, Recovery Rate Fair Value Inputs, Foreign Exchange Rates Fair Value Inputs, Foreign Exchange Rates Fair Value Inputs, Foreign Exchange Rates Fair Value Inputs, Base Correlation Fair Value Inputs, Base Correlation Fair Value Inputs, Base Correlation Length of Volatility of Japanese Yen to US Dollar Exchange Rate Length of Volatility of Japanese Yen to US Dollar Exchange Rate Length of Volatility of Japanese Yen to US Dollar Exchange Rate Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Options Outstanding - Stock Option Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options Outstanding - Weighted-Average Remaining Term (Yrs) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Options Outstanding - Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Options Outstanding - Weighted-Average Exercise Price Per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Options Exercisable - Stock Option Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Options Exercisable - Weighted-Average Remaining Term (Yrs.) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Options Exercisable - Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Options Exercisable - Weighted-Average Exercise Price Per Share Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments Schedule of Long-term Debt Instruments [Table Text Block] Stockholders' Equity Note [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Unrealized foreign currency translation gains (losses) Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Unrealized gains (losses) on investment securities Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Unrealized gains (losses) on derivatives Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Pension liability adjustment Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Accumulated Other Comprehensive Income [Roll Forward] Accumulated Other Comprehensive Income [Roll Forward] Accumulated Other Comprehensive Income [Roll Forward] Balance, beginning of period Accumulated Other Comprehensive Income (Loss), Net of Tax Other comprehensive income loss before reclassifications net of tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Amounts reclassified from accumulated other comprehensive income net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Balance, end of period Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Foreign currency forwards Foreign Exchange Forward [Member] Foreign currency options Foreign Exchange Option [Member] Interest rate swaptions Interest Rate Swaption [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Total gains (losses) recognized for derivatives Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Gains (losses) on derivatives excluded from effectiveness testing Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net Gains (losses) on derivatives included in effectiveness testing Gain loss from components included in assessment of fair value hedge effectiveness net Gain (loss) from components included in assessment of fair value hedge effectiveness net Gains (losses) recognized for hedged items Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Ineffectiveness recognized for fair value hedge Gain (Loss) on Fair Value Hedge Ineffectiveness, Net Organization, Consolidation and Presentation of Financial Statements [Abstract] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2015-03 [Member] Accounting Standards Update 2015-03 [Member] Statement, Business Segments [Axis] Segments [Axis] Segment [Domain] Segments [Domain] Aflac Japan Aflac Japan Member Aflac Japan Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Assets New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Assets New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Assets New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Liabilities New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Liabilities New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Liabilities Aflac Japan's percentage of the Company's total revenues Percentage of Company Revenue Percentage of Company Revenue. Percentage of the Company Assets Percentage of the Company Assets Percentage of Company Assets. Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities by Classification of Entity [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Not Consolidated Variable Interest Entity, Not Primary Beneficiary [Member] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Securities available for sale, fixed maturities, amortized cost Available-for-sale Debt Securities, Amortized Cost Basis Securities available for sale, fixed maturities, fair value Available-for-sale Securities, Debt Securities Securities available for sale, perpetual securities, amortized cost Available for sale Securities, Perpetual securities, amortized cost This item represents the aggregate amortized cost of investments in perpetual securities as of the balance sheet date and which are categorized as available-for-sale. Securities available for sale, perpetual securities, fair value Available-for-sale Securities Perpetual Securities For an unclassified balance sheet, total of perpetual securities categorized as neither held-to-maturity nor trading. Perpetual securities are reported at fair value; unrealized gains and losses of such securities are excluded from earnings and included in other comprehensive income, a separate component of shareholders' equity, unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain or loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below cost basis. Securities held to maturity, fixed maturities, fair value Assets, amortized cost Assets, Amortized Cost Disclosure Assets, Amortized Cost Disclosure Stock Options Outstanding and Exercisable Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block] Offsetting Liabilities [Table] Offsetting Liabilities [Table] Offsetting Assets and Liabilities [Axis] Offsetting Assets and Liabilities [Axis] Information by offsetting asset or liability. Offsetting Assets and Liabilities [Domain] Offsetting Assets and Liabilities [Domain] Offsetting by assets and liabilities. Offsetting liabilities Offsetting Liabilities [Member] Disclosure of information about derivative and financial liabilities that are subject to offsetting, including enforceable master netting arrangements. Transaction Type [Axis] Transaction Type [Axis] Transaction [Domain] Transaction [Domain] Securities lending and similar arrangements Securities lending and similar arrangements [Member] Securities lending and similar arrangements [Member] Offsetting Liabilities [Line Items] Offsetting Liabilities [Line Items] Gross amount of recognized derivative liabilities Derivative Liability, Fair Value, Gross Liability Gross amount of assets offset in balance sheet Derivative Liability, Fair Value, Gross Asset Net amount of derivative liabilities presented in balance sheet Derivative Liability Financial instruments, amount not offset against derivative liabilities in balance sheet Financial instruments, amount not offset against derivative liabilities in balance sheet Financial instruments, carrying value, amount not offset against derivative liabilities in balance sheet. Derivative, collateral, right to reclaim cash Derivative, Collateral, Right to Reclaim Cash Derivative Liability, Fair Value, Amount Offset Against Collateral Derivative Liability, Fair Value, Amount Offset Against Collateral Derivative, collateral, right to reclaim securities and cash Derivative, Collateral, Right To Reclaim Securities And Cash Derivative Collateral Right To Reclaim Securities And Cash Derivative, collateral, right to reclaim securities Derivative, Collateral, Right to Reclaim Securities Gross amounts of recognized financial instruments Gross Amounts of Recognized Financial Instruments The gross amounts of recognized financial instruments under the FASB ASU on Required Disclosures for Offsetting and Liabilities. Gross amounts offset in balance sheet Gross Amounts Offset in Statement of Financial Position The gross amounts offset to determine the net amounts presented in the statement of financial position. Net amounts of liabilities presented in balance sheet Net Amounts of Financial Instruments Presented in Balance Sheet Presents the net of gross amounts of recognized financial instruments and the gross amount offset in the Balance Sheet. Carrying value of financial instruments not offset in balance sheet Carrying value of financial instruments not offset in balance sheet Carrying value of financial instruments not offset in balance sheet. Collateral not offset in balance sheet Collateral not offset in balance sheet Collateral not offset in balance sheet Financial instruments, amount offset against collateral Financial instruments, amount offset against collateral Financial instruments amount offset against collateral Effects of Reinsurance [Table] Effects of Reinsurance [Table] Insurance Product Line [Axis] Products and Services [Axis] Insurance Product Line [Domain] Products and Services [Domain] Closed Block Closed block [Member] Closed block Member Effects of Reinsurance [Line Items] Effects of Reinsurance [Line Items] Committed reinsurance facility Committed Reinsurance Facility Committed Reinsurance Facility Reinsurance deferred profit liability Reinsurance deferred profit liability Reinsurance deferred profit liability Reinsurance recoverable Reinsurance Recoverables, Including Reinsurance Premium Paid Percent change in spot yen/dollar exchange rate Percent change in spot yen/dollar exchange rate Percent change in spot yen/dollar exchange rate Percent change in ceded reserves Percent change in ceded reserves Percent change in ceded reserves Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Table] Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Table] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Maturity Overnight and Continuous Maturity Overnight and on Demand [Member] Maturity up to 30 Days Maturity Less than 30 Days [Member] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] U.S. government and agencies US Treasury and Government [Member] Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items] Securities lending transactions Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred Gross amount of recognized liabilities for securities lending Securities Loaned and Securities Sold under Agreement to Repurchase, Gross Including Not Subject to Master Netting Arrangement Amounts related to agreements not included in offsetting disclosure in Note 4 Secured Borrowings, Gross, Difference, Amount SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 2.65% senior notes due February 2017 Senior Notes Two Point Six Five Percent Due February Twenty Seventeen [Member] Senior Notes Two Point Six Five Percent Due February Twenty Seventeen [Member] 2.40% senior notes due March 2020 Senior Notes Two Point Four Zero Percent Due March Twenty Twenty [Member] Senior Notes Two Point Four Zero Percent Due March Twenty Twenty [Member] 4.00% senior notes due February 2022 Senior Notes Four Point Zero Zero Percent Due February Twenty Twenty Two [Member] Senior Notes Four Point Zero Zero Percent Due February Twenty Twenty Two [Member] 3.625% senior notes due June 2023 Senior Notes Three Point Six Two Five Percent Due June Twenty Twenty Three [Member] Senior Notes Three Point Six Two Five Percent Due June Twenty Twenty Three [Member] 3.625% senior notes due November 2024 Senior Notes Three Point Six Two Five Percent Due November Twenty Twenty Four [Member] Senior Notes Three Point Six Two Five Percent Due November Twenty Twenty Four [Member] 3.25% senior notes due March 2025 Senior Notes Three Point Two Five Percent Due March Twenty Twenty Five [Member] Senior Notes Three Point Two Five Percent Due March Twenty Twenty Five [Member] 6.90% senior notes due December 2039 Senior Notes Six Point Nine Zero Percent Due December Twenty Thirty Nine [Member] Senior Notes Six Point Nine Zero Percent Due December Twenty Thirty Nine [Member] 6.45% senior notes due August 2040 Senior Notes Six Point Four Five Percent Due August Twenty Forty [Member] Senior Notes Six Point Four Five Percent Due August Twenty Forty [Member] 5.50% subordinated notes due September 2052 Subordinated Notes Five Point Five Zero Percent Due September Twenty Fifty Two [Member] Subordinated Notes Five Point Five Zero Percent Due September Twenty Fifty Two [Member] [Member] 2.26% yen-denominated Uridashi notes due September 2016 Yen Denominated Uridashi Notes Two Point Two Six Percent Due September Twenty Sixteen [Member] Yen Denominated Uridashi Notes Two Point Two Six Percent due September Twenty Sixteen [Member] 1.84% yen-denominated Samurai notes due July 2016 Yen Denominated Samurai Notes One Point Eight Four Percent Due July Twenty Sixteen [Member] Yen Denominated Samurai Notes One Point Eight Four Percent due July Twenty Sixteen [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt instrument, interest rate Debt Instrument, Interest Rate, Stated Percentage Debt instrument, principal amount Debt Instrument, Face Amount Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] 100 billion yen line of credit One hundred billion yen line of credit [Member] One hundred billion yen line of credit [Member] $100 million dollar line of credit One hundred million dollar line of credit [Member] One hundred million dollar line of credit [Member] 55 billion yen line of credit Fifty five billion yen line of credit [Member] Fifty five billion yen line of credit [Member] $50 million dollar line of credit Fifty million dollar line of credit [Member] Fifty million dollar line of credit [Member] Line of credit Line of Credit [Member] Notes Payable Notes Payable, Other Payables [Member] Line of credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Line of credit facility term Line of credit facility term Line of credit facility term Line of credit facility, interest rate description Line of Credit Facility, Interest Rate Description Line of credit facility, commitment fee percentage Line of Credit Facility, Commitment Fee Percentage Line of credit facility, amount outstanding Long-term Line of Credit Debt instrument, debt default, amount Debt Instrument, Debt Default, Amount Statement [Table] Statement [Table] Perpetual securities: Variable Interest Entity, Consolidated Variable Interest Entity, Primary Beneficiary [Member] Statement [Line Items] Statement [Line Items] Available-for-sale Securities Available-for-sale Securities [Table Text Block] Held-to-maturity Securities Held-to-maturity Securities [Table Text Block] Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Economic Maturities of Investments in Perpetual Securities Economic Maturities of Investments in Perpetual Securities [Table Text Block] Economic Maturities of Investments in Perpetual Securities [Table Text Block] Investment Exposures Exceeding Ten Percent Shareholders Equity Investment Exposures Exceeding 10 Percent Shareholders Equity [Table Text Block] Investment Exposures that Exceeded Ten Percent of Shareholders' Equity Gain (Loss) on Investments Gain (Loss) on Investments [Table Text Block] Other Than Temporary Impairment Losses on Investment Securities Other Than Temporary Impairment Losses on Investment Securities [Table Text Block] Other Than Temporary Impairment Losses on Investment Securities [Table Text Block] Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities [Table Text Block] Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities [Table Text Block] Investments Gross Unrealized Loss Aging Schedule of Unrealized Loss on Investments [Table Text Block] Investments in Unrealized Loss Position Investments In Unrealized Loss Position Table [Table Text Block] Bank and Financial Institution Investments in Unrealized Loss Position [Table Text Block] Investments in Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Securities Lending Transactions Accounted for as Secured Borrowings Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Table Text Block] Derivative Instruments, Gain (Loss) by Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Cash flow hedges Cash Flow Hedging [Member] Fair value hedges Fair Value Hedging [Member] Net investment hedge Net Investment Hedging [Member] Non-qualifying strategies Not Designated as Hedging Instrument [Member] Non-derivative hedging instruments Non-derivative Hedging Instruments [Member] Non-derivative Hedging Instruments [Member] Interest rate swaps Interest Rate Swap [Member] Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion) Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net Unrealized foreign currency translation gains (losses) during period Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Derivative Instruments, Gain (Loss) Recognized in Income, Net Derivative, Gain (Loss) on Derivative, Net Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion) Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net Derivative and other gains (losses) Gain (Loss) on Derivative Instruments, Net, Pretax Derivative and non-derivative hedging instruments gain loss recognized in other comprehensive income effective portion before tax Derivative and non-derivative hedging instruments gain loss recognized in other comprehensive income effective portion before tax Derivative and non-derivative hedging instruments gain loss recognized in other comprehensive income effective portion before tax Unrealized Gains (Losses) on Available-for-sale Securities Available-for-sale Securities, Gross Unrealized Gain (Loss) Deferred income taxes Accumulated other comprehensive income loss deferred income tax on investment securities Accumulated other comprehensive income loss, deferred income tax on investment securities. Shareholders' equity, unrealized gains (losses) on investment securities Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Reconciliation of Revenue from Segments to Consolidated [Table] Reconciliation of Revenue from Segments to Consolidated [Table] Aflac U.S. Aflac US Member Aflac U.S. Other business segments Other Segments [Member] Total Business Segments Operating Segments [Member] Corporate Corporate Segment [Member] Intercompany eliminations Consolidation, Eliminations [Member] Segment Reporting, Revenue Reconciling Item [Line Items] Segment Reporting, Revenue Reconciling Item [Line Items] Number of Reportable Insurance Business Segments Number of Reportable Segments Net earned premiums Premiums Earned, Net Net investment income Net Investment Income Other income (loss) Other Income Total revenues Revenues Other non-operating income (loss) Other Nonoperating Income (Expense) Included in Revenue The net amount of other income and expense amounts, the components of which are not separately disclosed on the income statement, resulting from ancillary business-related activities (that is, excluding major activities considered part of the normal operations of the business) also known as other nonoperating income (expense) recognized for the period. Such amounts may include: (a) dividends, (b) interest on securities, (c) net gains or losses on securities, (d) unusual costs, (e) gains or losses on foreign exchange transactions, and (f) miscellaneous other income and expense items included in revenue. Realized investment gains (losses), non-operating Gain (Loss) On Investments, Non-operating Gain (Loss) on Investments, Non-operating Gain (loss) on change in fair value of derivative, interest rate component, operating Gain (Loss) On Change In Fair Value Of Derivative, Interest Rate Component, Operating Gain (loss) on change in fair value of derivative, interest rate component, considered an operating gain (loss) when analyzing segment operations Description of Business and Basis of Presentation Business Description and Basis of Presentation [Text Block] Recently Adopted Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Description of Accounting Pronouncements Pending Adoption Description of New Accounting Pronouncements Not yet Adopted [Text Block] Commitments and Contingencies Disclosure [Abstract] Other Commitments [Table] Other Commitments [Table] Other Commitments [Axis] Other Commitments [Axis] Other Commitments [Domain] Other Commitments [Domain] Other Commitments [Line Items] Other Commitments [Line Items] Middle market loan commitment Middle Market Loan Commitment Middle Market Loan Commitment Commercial mortgage loan commitments Commercial Mortgage Loan Commitments Commercial Mortgage Loan Commitments Investments Classified by Economic Maturity Date [Table] Investments Classified By Economic Maturity Date [Table] Investments Classified by Economic Maturity Date [Table] Investments Classified by Economic Maturity Date [Line Items] Investments Classified By Economic Maturity Date [Line Items] Investments Classified by Economic Maturity Date [Line Items] Due in one year or less Available for sale Securities, Perpetual Securities, Economic Maturities, within One Year, Amortized Cost This item represents perpetual securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities. Due after one year through five years Available for sale Securities, Perpetual Securities, Economic Maturities, after One Through Five Years, Amortized Cost This item represents perpetual securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature after one year and through five years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities. Due after 10 years Available for sale Securities, Perpetual Securities, Economic Maturities, after Ten Years, Amortized Cost This item represents perpetual securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature after ten years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities. Total perpetual securities available for sale, amortized cost Available for sale Securities, Perpetual Securities, Economic Maturities, Amortized Cost This item represents the total of all perpetual securities grouped by economic maturity dates, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are categorized neither as held-to-maturity nor trading securities. Due in one year or less Available for sale Securities, Perpetual Securities, Economic Maturities, within One Year, Fair Value This item represents the fair value of perpetual securities which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities. Due after one year through five years Available for sale Securities, Perpetual Securities, Economic Maturities, after One Through Five Years, Fair Value This item represents the fair value of perpetual securities which are expected to mature after one year and through five years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities. Due after 10 years Available for sale Securities, Perpetual Securities, Economic Maturities, after Ten Years, Fair Value Available for sale Securities, Perpetual Securities, Economic Maturities, after Ten Years, Fair Value Total perpetual securities available for sale, fair value Available for Sale Securities Perpetual Securities Economic Maturities Fair Value This item represents the total of all perpetual securities grouped by economic maturity dates, at fair value, which are categorized neither as held-to-maturity nor trading securities. Schedule of Investments [Table] Schedule of Investments [Table] Bank loans Bank Loan Obligations [Member] Commercial mortgage loans Commercial mortgage loans [Member] Commercial mortgage loans [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Parent Company and Other Business Segments Parent Company and Other Business Segments [Member] Parent Company and Other Business Segments Schedule of Investments [Line Items] Schedule of Investments [Line Items] Amortized Cost Available-for-sale Securities, Amortized Cost Basis Available-for-sale securities, equity securities Available-for-sale Securities, Equity Securities Held to maturity securities transferred to available for sale securities, number of investments Held to Maturity Securities Transferred to Available for Sale Securities Number of Investments Number of investments reclassified during the period from the held-to-maturity portfolio to the available-for-sale portfolio. Number of issuers of VIEs not-consolidated Number of issuers Number of Issuers Middle Market Loan Receivable Middle Market Loan Receivable Middle Market Loan Receivable recorded at fair value on the acquisition date. Held-for-investment and carried on balance sheet at adjusted amortized cost in the other investment line on the consolidated balance sheet. Middle Market Loan Program Unfunded Amount Middle Market Loan Program Unfunded Amount Middle Market Loan Program Unfunded Amount Percentage that the lending policy requires that the fair value of the securities and/or unrestricted cash received as collateral be of the fair value of the loaned securities Collateral Requirements Minimum Percentage Collateral to Fair Value of Securities Loaned Under Security Lending Transactions Percentage that the lending policy requires that the fair value of the securities and/or cash received as collateral be of the fair value of the loaned securities in securities lending transactions. Available-for-sale equity securities, amortized cost basis Available-for-sale Equity Securities, Amortized Cost Basis Other investments held in unit trust, net of reserves, amortized cost Other investments held in unit trust, net of reserves, amortized cost Other investments held in unit trust, net of reserves, amortized cost Other investments, net of reserves, amortized cost Other investments, net of reserves, amortized cost Other investments, net of reserves, amortized cost Other investments held in unit trust, net of reserves, fair value Other investments held in unit trust, net of reserves, fair value Other investments held in unit trust, net of reserves, fair value Investment Exposures Individually Exceeded Ten Percent of Shareholders' Equity [Table] Investment Exposures Individually Exceeded Ten Percent of Shareholders' Equity [Table] Investment Issuer [Axis] Investment Issuer [Axis] Investment Issuer [Domain] Investment Issuer [Domain] Japan National Government Japan National Government [Member] Japan National Government [Member] Summary of Investment Holdings [Line Items] Summary of Investment Holdings [Line Items] Credit Rating Debt Instrument, Credit Rating Amortized Cost Total debt and perpetual securities amortized cost Total debt and perpetual securities at amortized cost. Fair Value Total debt and perpetual securities fair value Total debt and perpetual securities at fair value. Stockholders Equity Note [Table] Stockholders Equity Note [Table] Stockholders Equity Note [Table] Treasury Stock Treasury Stock [Member] Stockholders Equity Note [Line Items] Stockholders Equity Note [Line Items] Stockholders Equity Note [Line Items] Common Stock Issued [Roll Forward] Common Stock Issued [Roll Forward] Common Stock Issued [Roll Forward] Balance, beginning of period Common Stock, Shares, Issued Exercise of stock options and issuance of restricted shares Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Balance, end of period Treasury Stock [Roll Forward] Treasury Stock Issued [Roll Forward] Treasury Stock Issued [Roll Forward] Balance, beginning of period Treasury Stock, Shares Stock Acquired In Open Market, Shares Stock Acquired In Open Market, Shares Number of shares that have been repurchased from the open market during the period Other purchases Other Additions During Period Shares Other additions to number of shares during period. Shares issued to AFL Stock Plan Stock Issued During Period, Shares, Dividend Reinvestment Plan Exercise of stock options Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Other dispositions Stock Issued During Period, Shares, Other Balance, end of period Shares outstanding, end of period Common Stock, Shares, Outstanding DERIVATIVE INSTRUMENTS Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of Gain (Loss) on Investments [Table] Schedule of Gain (Loss) on Investments [Table] Debt Security Category [Axis] Investments by Category [Axis] Marketable Securities and Investments Held at Cost [Domain] Marketable Securities and Investments Held at Cost [Domain] Available-for-sale securities Available-for-sale Securities [Member] Fixed maturities: Debt Securities [Member] Derivatives and other Derivatives and other [Member] Derivatives and other [Member] Gain (Loss) on Investments [Line Items] Gain (Loss) on Investments [Line Items] Gross gains from sales Available-for-sale Securities, Gross Realized Gains Gross losses from sales Available-for-sale Securities, Gross Realized Losses Net gains (losses) from redemptions Gains Losses From Redemptions Of Securities Net Gains (losses) from redemptions of securities, net Other-than-temporary impairment losses realized Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net Derivative gains (losses) Total realized investment gains (losses) Gain (Loss) on Investments Corporate bonds Corporate Bond Securities [Member] Type of Impairment [Axis] Type of Impairment [Axis] Type of Impairment [Axis] Type of Impairment [Domain] Type of Impairment [Domain] Type of Impairment [Domain] Change in intent impairment Change In Intent Impairment [Member] Change In Intent Impairment [Member] Other than temporary impairment losses Fair Value Inputs, Liabilities, Quantitative Information [Table] Fair Value Inputs, Liabilities, Quantitative Information [Table] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Liability Liability [Member] Fair Value Inputs, Liabilities, Quantitative Information [Line Items] Fair Value Inputs, Liabilities, Quantitative Information [Line Items] Liability derivatives Liabilities, fair value disclosure Financial and Nonfinancial Liabilities, Fair Value Disclosure Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Reconciliation of Assets from Segment to Consolidated [Table] Reconciliation of Assets from Segment to Consolidated [Table] Segment Reporting, Asset Reconciling Item [Line Items] Segment Reporting, Asset Reconciling Item [Line Items] Assets Assets Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Performance based Vesting Condition Performance Based Vesting Condition Member Performance-based Vesting Condition Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type [Axis] Award Type [Axis] Share-based Compensation Arrangements by Share-based Payment Award, Award Type [Domain] Equity Award [Domain] Stock Option Plan Effective until February 2007 Stock Option Plan Effective Until February 2007 Member Stock Option Plan Effective until February 2007 Second Stock Option Plan Second Stock Option Plan [Member] Second Stock Option Plan [Member] Restricted Stock Restricted Stock [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Number of long-term incentive compensation plans Number of Incentive Compensation Plans Number of Incentive Compensation Plans Stock option plan, term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Stock option plan, vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Shares available for future grants under the long-term incentive plan Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Proceeds from stock options exercised Employee Service Share-based Compensation, Cash Received from Exercise of Stock Options Tax benefit from stock options exercised Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options Total compensation cost not yet recognized, restricted stock awards Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Total compensation cost not yet recognized, restricted stock awards, shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Total compensation cost not yet recognized, restricted stock awards, weighted-average period (in years) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Fair Value, Assets and Liabilities Measured on Recurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Government and agencies Government and Agencies Debt Securities [Member] Government and Agencies Debt Securities Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets: Assets, Fair Value Disclosure [Abstract] Other Investments Other Investments Carried at Fair Value, Fair Value Disclosure Other Investments Carried at Fair Value, Fair Value Disclosure Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Total assets Liabilities: Liabilities, Fair Value Disclosure [Abstract] Total liabilities Income Statement [Abstract] 8.50% senior notes due May 2019 Senior Notes Eight Point Five Zero Percent Due May Twenty Nineteen [Member] Senior Notes Eight Point Five Zero Percent Due May Twenty Nineteen [Member] Extinguishment of debt, make-whole premium Gain (Loss) on Extinguishment of Debt Revenues: Revenues [Abstract] Net premiums, principally supplemental health insurance Realized investment gains (losses): Realized Investment Gains (Losses) [Abstract] Sales and redemptions Marketable Securities, Realized Gain (Loss), Excluding Other than Temporary Impairments Derivative and other gains (losses) Gain loss on derivative instruments and other net pretax Aggregate net gain (loss) on derivative instruments and other assets recognized in earnings during the period, before tax effects. Other income (loss) Other income (loss) Reflects the sum of all other revenue and income (loss) recognized by the entity in the period not otherwise specified in the income statement. Benefits and expenses: Benefits, Losses and Expenses [Abstract] Benefits and claims, net Policyholder Benefits and Claims Incurred, Net Acquisition and operating expenses: Acquisition and operating expenses [Abstract] Acquisition and Operating Expenses [Abstract] Amortization of deferred policy acquisition costs Deferred Policy Acquisition Cost, Amortization Expense Insurance commissions Insurance Commissions Insurance expenses Selling, General and Administrative Expense Interest expense Interest Expense Other expenses Other Cost and Expense, Operating Total acquisition and operating expenses Acquisition and Operating Cost and Expenses Total acquisition and operating expenses, which includes amortization of deferred policy acquisition costs, insurance commissions, insurance expenses, interest expense and other operating expenses. Total benefits and expenses Benefits, Losses and Expenses Earnings before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income taxes Income Tax Expense (Benefit) Net earnings Net Income (Loss) Attributable to Parent Net earnings per share: Earnings Per Share [Abstract] Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Weighted-average outstanding common shares used in computing earnings per share (In thousands): Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Cash dividends per share Common Stock, Dividends, Per Share, Cash Paid BENEFIT PLANS Pension and Other Postretirement Benefits Disclosure [Text Block] Anti-dilutive share-based awards Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount NOTES PAYABLE Debt and Capital Leases Disclosures [Text Block] Statement of Stockholders' Equity [Abstract] Common stock: Common Stock [Member] Additional paid-in capital: Additional Paid-in Capital [Member] Retained earnings: Retained Earnings [Member] Accumulated other comprehensive income (loss): AOCI Attributable to Parent [Member] Treasury stock: Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, beginning of period Stockholders' Equity Attributable to Parent Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Share-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Net earnings Dividends to shareholders Dividends, Common Stock, Cash Unrealized foreign currency translation gains (losses) during period, net of income taxes Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Unrealized gains (losses) on investment securities during period, net of income taxes and reclassification adjustments Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Unrealized gains (losses) on derivatives during period, net of income taxes Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Pension liability adjustment during period, net of income taxes Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Purchases of treasury stock Treasury Stock, Value, Acquired, Cost Method Treasury stock reissued Stock Issued During Period, Value, Treasury Stock Reissued Balance, end of period SHARE-BASED COMPENSATION Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Derivative Instruments and Hedging Activities Disclosure [Table] Derivative [Table] Credit Rating [Axis] Credit Rating [Axis] Credit Rating [Axis] Type of Credit Rating [Domain] Type of Credit Rating [Domain] Type of Credit Rating [Domain] AA AA Credit Rating [Member] AA Credit Rating A ACredit Rating [Member] A Credit Rating [Member] BBB BBB Credit Rating [Member] BBB Credit Rating Derivative Instruments and Hedging Activities Disclosure [Line Items] Derivative [Line Items] Notional Amount of Derivatives Derivative, Notional Amount Asset Derivatives Fair Value Fair Value, Concentration of Risk, Derivative Instruments, Assets Liability Derivatives Fair Value Fair Value, Concentration of Risk, Derivative Instruments, Liabilities Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification Out Of Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Member] Sales and redemptions Other than temporary impairment losses realized Acquisition and operating expenses, actuarial gains (losses) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax Acquisition and operating expenses, prior service (cost) credit Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax Total before tax Income tax (expense) or benefit Net of tax The expected U.S. tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Share Repurchases, by Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] Share Repurchase Program Share Repurchase Program [Member] Share Repurchase Program [Member] Common stock, share repurchase, dollar amount Payments for Repurchase of Common Stock Remaining common stock available for purchase under share repurchase authorizations Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased Investments, Unrealized Loss Position [Table] Investments, Unrealized Loss Position [Table] Investments, Unrealized Loss Position [Table] Investments, Unrealized Loss Position [Line Items] Investments, Unrealized Loss Position [Line Items] Investments, Unrealized Loss Position [Line Items] Total Fair Value Securities Continuous Unrealized Loss Position Fair Value This item represents the fair value of securities in an unrealized loss position which are categorized as available-for-sale or held-to-maturity. Total Unrealized Losses Securities Continuous Unrealized Loss Position Aggregate Losses This item represents the excess of [amortized] cost over fair value of securities in a loss position and which are categorized as available-for-sale or held-to-maturity. Less than 12 months Fair Value Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value This item represents the fair value of securities categorized as available-for-sale or held-to-maturity that have been in a continuous unrealized loss position for less than twelve months. Less than 12 months Unrealized Losses Securities Continuous Unrealized Loss Position Less than 12 months Aggregate Losses This item represents the excess of [amortized] cost over fair value of securities that have been in a loss position for less than twelve months for those securities which are categorized as available-for-sale or held-to-maturity . 12 months or longer Fair Value Securities Continuous Unrealized Loss Position Twelve Months or Longer Fair Value This item represents the fair value of securities categorized as available-for-sale or held-to-maturity that have been in a continuous unrealized loss position for twelve months or longer. 12 months or longer Unrealized Losses Securities Continuous Unrealized Loss Position 12 Months Or Longer Aggregate Losses This item represents the excess of [amortized] cost over fair value of securities that have been in a loss position for twelve months or longer for those securities which are categorized as available-for sale or held-to-maturity . Schedule of Common Stock Outstanding Roll Forward Schedule of Common Stock Outstanding Roll Forward [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Reclassification Out Of Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value Hierarchy [Domain] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets: Assets [Abstract] Other investments carried at amortized cost Other Investments Carried at Amortized Cost Other Investments Carried at Amortized Cost Other investments carried at amortized cost, fair value Other Investments Carried at Amortized Cost, Fair Value Disclosure Other Investments Carried at Amortized Cost, Fair Value Disclosure Total financial instruments assets not carried at fair value Total Financial Instrument Assets Not Carried at Fair Value Total Financial Instrument Assets Not Carried at Fair Value Assets fair value disclosure financial instruments carried at cost Assets Fair Value Disclosure Financial Instruments Carried at Cost This element represents assets reported on the balance sheet that are carried at cost or amortized cost but for which fair value is disclosed. Liabilities Liabilities [Abstract] Other policyholder funds Other Policyholder Funds Other policyholders' funds fair value disclosure Other policyholders' funds fair value disclosure Other policyholders' funds fair value disclosure Notes payable Notes Payable Notes payable fair value disclosure Notes Payable, Fair Value Disclosure Total financial instrument liabilities not carried at fair value Total Financial Instrument Liabilities Not Carried At Fair Value Total Financial Instrument Liabilities Not Carried At Fair Value Liabilities fair value disclosure financial instruments carried at cost Liabilities Fair Value Disclosure Financial Instruments Carried At Cost This element represents liabilities reported on the balance sheet that are carried at cost or amortized cost but for which fair value is disclosed. Health care plan, retirement age for eligibility, (in years) Postretirement Medical Benefits Qualifying Age Qualifying Age for Postretirement Medical Benefits Health care plan, number of years of service for eligibility Postretirement Medical Benefits Number Of Years Of Service For Eligibility Postretirement Medical Benefits Number Of Years Of Service For Eligibility Health care plan, retirement age and years of service combined years for eligibility (rule of 80) Postretirement Medical Benefits Qualifying Age And Service Period Combined Retirement age and years of service combined years for eligibility for postretirement medical benefits. Amount of years active employees have left to meet rule of 80 in order to be eligible for postretirement medical benefits Amount of years left to meet rule of eighty for active employees to be eligible for postretirement medical benefits The amount of years active employees have left to meet the rule of 80 in order to be eligible for postretirement medical benefits. Amount of years left to meet 15 year service requirement for active employees age 55 or older to be eligible for postretirement medical benefits Amount of years left to meet fifteen year service requirement for active employees age fifty five or older to be eligible for postretirement medical benefits Amount of years left to meet 15 year service requirement for active employees age 55 or older to be eligible for postretirement medical benefits Employer contributions Defined Benefit Plan, Contributions by Employer Investments Classified by Contractual Maturity Date [Table] Investments Classified by Contractual Maturity Date [Table] Investments Classified by Contractual Maturity Date [Table] Investments Classified by Contractual Maturity Date [Line Items] Investments Classified by Contractual Maturity Date [Line Items] Investments Classified by Contractual Maturity Date [Line Items] Available for sale: Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract] Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis Due after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis Due after five years through 10 years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis Due after 10 years Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis Mortgage- and asset-backed securities Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis Total fixed maturities available for sale, amortized cost Held to maturity: Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract] Due in one year or less Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount Due after one year through five years Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount Due after five years through 10 years Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount Due after 10 years Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount Mortgage- and asset-backed securities Held-to-maturity Securities, Debt Maturities, without Single Maturity Date, Net Carrying Amount Total fixed maturities held to maturity, amortized cost Available for sale: Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Due after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value Due after five years through 10 years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value Due after 10 years Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value Mortgage- and asset-backed securities Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value Total fixed maturities available for sale, fair value Held to maturity: Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] Due in one year or less Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value Due after one year through five years Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value Due after five years through 10 years Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value Due after 10 years Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value Mortgage- and asset-backed securities Held-to-maturity Securities, Debt Maturities, without Single Maturity Date, Fair Value Total fixed maturities held to maturity, fair value Fair Value and Notional Amount of Derivatives with Counterparty Credit Risk Fair Value and Notional Amount of Derivatives With Counterparty Credit Risk [Table Text Block] Fair Value and Notional Amount of Derivatives with Counterparty Credit Risk [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance Derivative Instruments, Gain (Loss) [Table Text Block] Offsetting Assets Offsetting Assets [Table Text Block] Offsetting Liabilities Offsetting Liabilities [Table Text Block] Statement of Comprehensive Income [Abstract] Other comprehensive income (loss) before income taxes: Other Comprehensive Income (Loss), before Tax [Abstract] Unrealized gains (losses) on investment securities: Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, [Abstract] Unrealized holding gains (losses) on investment securities during period Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Reclassification adjustment for realized (gains) losses on investment securities included in net earnings Other Comprehensive Income Reclassification Adjustment For Sale And Write Down Of Securities Included In Net Income Before Tax Pre tax reclassification adjustment for gains or losses realized upon the sale of securities and losses realized upon the write-down of securities. Unrealized gains (losses) on derivatives during period Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax Pension liability adjustment during period Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax Total other comprehensive income (loss) before income taxes Other Comprehensive Income (Loss), before Tax Income tax expense (benefit) related to items of other comprehensive income (loss) Other Comprehensive Income (Loss), Tax Other comprehensive income (loss), net of income taxes Total comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent COMMITMENTS AND CONTINGENT LIABILITIES Commitments and Contingencies Disclosure [Text Block] Statement of Cash Flows [Abstract] Treasury Stock Activity By Type [Axis] Treasury Stock Activity By Type [Axis] Treasury Stock Activity By Type [Axis] Treasury Stock Activity By Type [Domain] Treasury Stock Activity By Type [Domain] Treasury Stock Activity By Type [Domain] Associate stock bonus Associate Stock Bonus [Member] Associate Stock Bonus [Member] Shareholder dividend reinvestment Shareholder Dividend Reinvestment [Member] Shareholder Dividend Reinvestment [Member] Share-based compensation grants Share Based Compensation Grants [Member] Share Based Compensation Grants [Member] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net earnings to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Change in receivables and advance premiums Increase (Decrease) in Receivables Increase in deferred policy acquisition costs Increase (Decrease) in Deferred Policy Acquisition Costs Increase in policy liabilities Increase (Decrease) in Insurance Liabilities Change in income tax liabilities Increase (Decrease) in Income Taxes Payable Realized investment (gains) losses Other, net Other Noncash Income (Expense) Net cash provided (used) by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Proceeds from investments sold or matured: Proceeds from Sale, Maturity and Collection of Investments [Abstract] Securities available for sale: Proceeds from Sale and Maturity of Available-for-sale Securities [Abstract] Fixed maturities sold Proceeds from Sale of Available-for-sale Securities, Debt Fixed maturities matured or called Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities Perpetual securities matured or called Proceeds from maturities prepayments and calls of available-for-sale perpetual securities Proceeds from maturities prepayments and calls of available-for-sale perpetual securities Equity securities sold Proceeds from Sale of Available-for-sale Securities, Equity Securities held to maturity: Proceeds from Sale and Maturity of Held-to-maturity Securities [Abstract] Fixed maturities matured or called Proceeds from Maturities, Prepayments and Calls of Held-to-maturity Securities Costs of investments acquired: Payments to Acquire Investments [Abstract] Available for sale fixed maturities acquired Payments to Acquire Available-for-sale Securities, Debt Available for sale equity securities acquired Payments to Acquire Available-for-sale Securities, Equity Other investments, net Payments For (Proceeds From) Other Investments The net cash inflow (outflow) associated with the acquisition or disposal of other investments held by the entity for investment purposes not otherwise defined in the taxonomy. Settlement of derivatives, net Payments for (Proceeds from) Hedge, Investing Activities Cash received (pledged or returned) as collateral, net Increase Decrease In Collateral Held For Securities Lending And Derivatives The increase (decrease) during the period in the carrying amount of assets, which may include but are not limited to cash and investments, received as collateral pertaining to securities loaned to a counterparty to a securities lending transaction or pertaining to collateral posting requirements for derivative activity. Includes the change during the period in any unrealized gain or loss on such investments. Other, net Payments for (Proceeds from) Other Investing Activities Net cash provided (used) by investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Purchases of treasury stock Proceeds from borrowings Proceeds from Issuance of Long-term Debt and Capital Securities, Net Principal payments under debt obligations Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities Dividends paid to shareholders Payments of Dividends Change in investment-type contracts, net Net Change Annuities and Investment Certificates Treasury stock reissued Proceeds from Sale of Treasury Stock Other, net Proceeds from (Payments for) Other Financing Activities Net cash provided (used) by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net change in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents, end of period Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] Income taxes paid Income Taxes Paid, Net Interest paid Interest Paid Noncash interest Other Noncash Expense Impairment losses included in realized investment losses Capital lease obligations incurred Capital Lease Obligations Incurred Noncash financing activities: Noncash Investing and Financing Items [Abstract] Treasury stock issued for: Treasury Stock Issued For [Abstract] Treasury Stock Issued For [Abstract] Treasury stock issued Stock Issued Statement of Financial Position [Abstract] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Investments Other Than Consolidated Variable Interest Entities Investments other than Consolidated Variable Interest Entities [Member] Investments Other Than Consolidated Variable Interest Entities Securities available for sale, equity securities, cost Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Balance, beginning of period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Realized investment gains (losses) included in earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Unrealized gains (losses) included in other comprehensive income (loss) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Transfers into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Transfers out of Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Balance, end of period Change in unrealized gains (losses) still held Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Balance, beginning of period Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Realized gains or losses included in earnings Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings Unrealized gains or losses included in other comprehensive income (loss) Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss) Purchases Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases Issuances Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Issues Sales Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales Settlements Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements Transfers into Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3 Transfers out of Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3 Balance, end of period Changes in unrealized gain (losses) still held Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss) Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Third party pricing vendor valuation technique Third party pricing vendor valuation technique [Member] Third party pricing vendor valuation technique [Member] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Hedging Relationship [Axis] Derivatives, Fair Value, by Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other assets Other Assets [Member] Other liabilities Other Liabilities [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Net Derivatives Notional Amount Net Derivatives Fair Value Derivative, Fair Value, Net Asset derivatives fair value Derivative Asset, Fair Value, Gross Asset Liability Derivatives Fair Value Effects of Reinsurance Effects of Reinsurance [Table Text Block] SHAREHOLDERS' EQUITY Stockholders' Equity Note Disclosure [Text Block] Capitalized Lease Obligations Capital Lease Obligations [Member] Notes payable Debt and Capital Lease Obligations All other Other Insurance Product Line [Member] Direct premium income Direct Premiums Earned Ceded premiums Ceded Premiums Earned Assumed premiums earned Assumed Premiums Earned Net premium income Direct benefits and claims Policyholder Benefits and Claims Incurred, Direct Ceded benefits and claims Policyholder Benefits and Claims Incurred, Ceded Assumed benefits and claims from other companies Policyholder Benefits and Claims Incurred, Assumed Benefits and claims, net Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Other Investments, amortized cost Other Investments Other investments, fair value Other investments, fair value disclosure Other investments, fair value disclosure Asset derivative, amortized cost Derivative assets amortized cost disclosure Derivative assets amortized cost disclosure Liability derivatives, amortized cost Derivative liabilities amortized cost disclosure Derivative liabilities amortized cost disclosure Liabilities Liabilities Reconciliation of Revenue from Segments to Consolidated Reconciliation of Revenue from Segments to Consolidated [Table Text Block] Reconciliation of Operating Profit (Loss) from Segments to Consolidated Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Reconciliation of Assets from Segment to Consolidated Reconciliation of Assets from Segment to Consolidated [Table Text Block] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Cost or Amortized Cost Gross Unrealized Gains Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Losses Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax Fair Value Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] U.S. dollar-denominated equities U.S. Dollar-Denominated Equities [Member] U.S. dollar-denominated equities [Member] Profit repatriation [Axis] Profit repatriation [Axis] Profit repatriation [Axis] Profit repatriation [Domain] Profit repatriation [Domain] [Domain] for Profit repatriation [Axis] February twenty fifteen profit repatriation February Twenty Sixteen Profit Repatriation [Member] February Twenty Sixteen Profit Repatriation [Member] July twenty sixteen profit repatriation July Twenty Sixteen Profit Repatriation [Member] July Twenty Sixteen Profit Repatriation [Member] Future profit repatriation Future profit repatriation [Member] Future profit repatriation [Member] Foreign currency forwards and options Foreign currency forwards and options [Member] Foreign currency forwards and options [Member] Hedging activity, weighted-average period (in years) Hedging activity, weighted-average period (in years) Hedging activity, weighted-average period (in years) Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Number of currencies related to foreign currency swaps Number of Currencies Number of Currencies Related to Foreign Currency Swaps Number of counterparties Number of counterparties Total number of counterparties to derivative contracts. Number of counterparties that comprise majority of aggregate notional amount of swaps Number of counterparties that comprise majority of aggregate notional amount of swaps Number of counterparties that comprise majority of aggregate notional amount of swaps Percentage of notional amount of swaps from certain number of counterparties Percentage of notional amount of swaps from certain number of counterparties Percentage of the notional amount of swaps from certain number of counterparties Collateral Already Posted, Aggregate Fair Value Collateral Already Posted, Aggregate Fair Value Derivative, Net Liability Position, Aggregate Fair Value Derivative, Net Liability Position, Aggregate Fair Value Collateral obtained from third parties Derivative Asset, Fair Value of Collateral Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Derivative, Gain (Loss) on Derivative, Net Credit Rating [Axis] External Credit Rating by Grouping [Axis] Credit Rating [Domain] External Credit Rating by Grouping [Domain] Investment Grade External Credit Rating, Investment Grade [Member] Percentage of Total Investments in an Unrealized Loss Position Percentage Of Total Investments In Unrealized Loss Position Percentage of Total Investments in Unrealized Loss Position Percentage of Total Unrealized Losses Percentage of Total Unrealized Losses Percentage of Total Unrealized Losses Percentage of unrealized losses attributable to securities that were investment grade Securities Continuous Unrealized Loss Position Aggregate Losses Percentage Investment Grade or Below Investment Grade Securities, Continuous Unrealized Loss Position, Aggregate Losses, Percentage Investment Grade or Below Investment Grade. Fair Value Hierarchy, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value Hierarchy Levels of Assets and Liabilities Carried at Cost or Amortized Cost Schedule Of Fair Value Of Assets And Liabilities Carried At Cost With Fair Values Disclosed [Table Text Block] Tabular disclosure of assets and liabilities, including [financial] instruments, carried at cost or amortized cost whose fair values are only disclosed. The disclosures contemplated herein include the fair value at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). Fair Value Assets Available-for-Sale Securities Primary Pricing Sources Fair Value Assets Available-for-Sale Securities Primary Pricing Sources Table Text Block [Table Text Block] [Table Text Block] for Fair Value Assets Available-for-Sale Securities Primary Pricing Sources Table Text Block [Table] Fair Value Assets Held-To-Maturity Securities Primary Pricing Sources Fair Value Assets Held-To-Maturity Securities Primary Pricing Sources Table Text Block [Table Text Block] Fair Value Assets Held-To-Maturity Securities Primary Pricing Sources Table Text Block [Table Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Fair Value Inputs Assets Quantitative Information Fair Value Inputs, Assets, Quantitative Information [Table Text Block] Fair Value Inputs Liabilities Quantitative Information Fair Value Inputs, Liabilities, Quantitative Information [Table Text Block] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Interest expense, noninsurance operations Interest Expense [Member] Corporate and eliminations Corporate And Eliminations Member Corporate and Eliminations Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] Pretax operating earnings Operating Income (Loss) Other non-operating income (loss) Other Nonoperating Income (Expense) Income taxes applicable to pretax operating earnings Income taxes applicable to pretax operating earnings Income taxes applicable to pretax operating earnings. Effect of foreign currency translation on operating earnings Effect of foreign currency translation on operating earnings Effect of foreign currency translation on operating earnings. Gain (Loss) on Investments Offsetting Assets [Table] Offsetting Assets [Table] Offsetting assets Offsetting Assets [Member] Disclosure of information about derivative and financial assets that are subject to offsetting, including enforceable master netting arrangements. Offsetting Assets [Line Items] Offsetting Assets [Line Items] Debt Instrument, Face Amount Gross amount of recognized derivative assets Gross amount of liabilities offset in balance sheet Derivative Asset, Fair Value, Gross Liability Net amount of derivative assets presented in balance sheet Financial instruments, amount not offset against derivative assets in balance sheet Financial instruments, amount not offset against derivative assets in balance sheet Financial instruments, carrying value, amount not offset against derivative assets in balance sheet Derivative, collateral, obligation to return cash and securities Derivative, Collateral, Obligation to Return Cash and Securities Amount of obligation to return cash and securities collateral under master netting arrangements that have not been offset against derivative assets. Derivative asset, fair value, amount offset against collateral Derivative Asset, Fair Value, Amount Offset Against Collateral Net amounts of assets presented in balance sheet Derivative, collateral, obligation to return securities Derivative, Collateral, Obligation to Return Securities Derivative, Collateral, Obligation to Return Cash Derivative, Collateral, Obligation to Return Cash Investments and Cash Investments and Cash [Abstract] Securities available for sale, at fair value: Available-for-sale Securities [Abstract] Fixed maturities Perpetual securities Equity securities Securities held to maturity, at amortized cost: Held-to-maturity Securities, Debt Maturities [Abstract] Fixed maturities Other Investments Cash and cash equivalents Total investments and cash Investments and Cash Receivables Premiums and Other Receivables, Net Accrued investment income Accrued Investment Income Receivable Deferred policy acquisition costs Deferred Policy Acquisition Costs Property and equipment, at cost less accumulated depreciation Property, Plant and Equipment, Net Other Other Assets Total assets Liabilities and shareholders' equity Liabilities and Equity [Abstract] Liabilities: Policy liabilities: Policy liabilities [Abstract] Policy liabilities [Abstract] Future policy benefits Liability for Future Policy Benefits Unpaid policy claims Liability for Unpaid Claims and Claims Adjustment Expense, Net Unearned premiums Unearned Premiums Other policyholders’ funds Total policy liabilities Total Policy Liabilities Total policy liabilities includes future policy benefits, unpaid policy claims, unearned premiums and other policyholders' funds. Income Taxes Taxes Payable Payables for return of cash collateral on loaned securities Obligation To Return Cash or Securities Received as Collateral The cash or fair value of collateral received by the entity associated with securities borrowed that must be returned if the counterparty fulfills its obligations. It appears on the balance sheet as a liability and has a corresponding asset on the balance sheet, either cash or securities, depending on which was received as the collateral. Other Other Liabilities Total liabilities Shareholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2016 and 2015; issued 670,764 shares in 2016 and 669,723 shares in 2015 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income (loss): Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Unrealized foreign currency translation gains (losses) Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Unrealized gain (losses) on investment securities Unrealized gains (losses) on derivatives Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Pension liability adjustment Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Treasury stock, at average cost Treasury Stock, Value Total shareholders’ equity Total liabilities and shareholders’ equity Liabilities and Equity