Retirement Benefits [Abstract] Stock-Based Compensation Expense Share-based Payment Arrangement, Cost by Plan [Table Text Block] Activity for Restricted Stock Awards Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] Weighted-Average Fair Value of Stock Options Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Activity for Option Plans Share-based Payment Arrangement, Option, Activity [Table Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Customer contracts/relationships Customer Contracts [Member] Trade names and technology Trade Names [Member] Provider contracts Contractual Rights [Member] Noncompetes and other Noncompetes And Other [Member] Noncompetes and Other [Member] Acquired Finite-Lived Intangible Assets [Line Items] Acquired Finite-Lived Intangible Assets [Line Items] Intangible Assets Finite-Lived Intangible Assets, Net [Abstract] Weighted Average Life Finite-Lived Intangible Asset, Useful Life Cost Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Net Finite-Lived Intangible Assets, Net Condensed Financial Information Disclosure [Abstract] Condensed Financial Statements [Table] Condensed Financial Statements [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Parent Company Parent Company [Member] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Net cash provided 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] Acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Purchase of equity method investment in Kindred at Home Payments to Acquire Equity Method Investments Capital contributions to operating subsidiaries Capital Contributions To Operating Subsidiaries Capital contributions to operating subsidiaries Purchases of investment securities Payments to Acquire Debt Securities, Available-for-sale Proceeds from sale of investment securities Proceeds from Sale of Debt Securities, Available-for-sale Maturities of investment securities Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Purchases of property and equipment, net Payments to Acquire Property, Plant, and Equipment Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from issuance of senior notes, net Proceeds from Issuance of Senior Long-term Debt (Repayments) proceeds from issuance of commercial paper, net Proceeds from (Repayments of) Commercial Paper Proceeds from term loan Proceeds from Notes Payable Repayment of term loan Repayments of Notes Payable Repayment of long-term debt Repayments of Long-term Debt Change in book overdraft Increase (Decrease) in Book Overdrafts Common stock repurchases Payments for Repurchase of Common Stock Dividends paid Payments of Dividends Proceeds From Stock Options Exercised And Other Proceeds From Stock Options Exercised And Other Proceeds From Stock Options Exercised And Other Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents at end of period Debt Disclosure [Abstract] DEBT Debt Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] COMMITMENTS, GUARANTEES AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Income Tax Disclosure [Abstract] Income tax provision at federal statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount States, net of federal benefit, and Puerto Rico Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Tax exempt investment income Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Health insurance industry fee Effective Income Tax Rate Reconciliation, Health Insurer Fee, Amount Effective Income Tax Rate Reconciliation, Health Insurer Fee, Amount Nondeductible executive compensation Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Payment Arrangement, Amount Tax reform Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount KMG sale Effective Income Tax Rate Reconciliation, Disposition of Business, Amount Other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Provision for income taxes Income Tax Expense (Benefit) Insurance [Abstract] Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Retail Retail [Member] Group and Specialty Group And Specialty [Member] Group And Specialty [Member] Liability for Claims and Claims Adjustment Expense [Line Items] Liability for Claims and Claims Adjustment Expense [Line Items] Benefits payable, net of reinsurance Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net Reinsurance recoverable on unpaid claims Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Total benefits payable, gross Liability for Claims and Claims Adjustment Expense Net income Net Income (Loss) Attributable to Parent Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Change in gross unrealized investment losses/gains Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax Effect of income taxes Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Total change in unrealized investment gains/losses, net of tax Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Reclassification adjustment for net realized gains included in investment income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Effect of income taxes Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Total reclassification adjustment, net of tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive income attributable to our equity method investment in Kindred at Home Comprehensive Income (Loss), Net of Tax, Attributable To Equity Method Investments Comprehensive Income (Loss), Net of Tax, Attributable To Equity Method Investments Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Investments, Debt and Equity Securities [Abstract] Schedule of Investment Securities Classified as Current and Long-Term Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Schedule of Gross Unrealized Losses and Fair Value of Securities Schedule of Unrealized Loss on Investments [Table Text Block] Schedule of Realized Gains (Losses) Related to Investment Securities Included Within Investment Income Schedule of Realized Gain (Loss) [Table Text Block] Schedule of Contractual Maturity of Debt Securities Available for Sale Investments Classified by Contractual Maturity Date [Table Text Block] Short-duration Insurance Contracts, Claims Development [Table] Short-duration Insurance Contracts, Claims Development [Table] Short-duration Insurance Contracts, Accident Year [Axis] Short-duration Insurance Contracts, Accident Year [Axis] Short-duration Insurance Contracts, Accident Year [Domain] Short-duration Insurance Contracts, Accident Year [Domain] 2017 Claims Incurred Year Short-duration Insurance Contracts, Accident Year 2017 [Member] 2018 Claims Incurred Year Short-duration Insurance Contracts, Accident Year 2018 [Member] 2019 Claims Incurred Year Short-Duration Insurance Contract, Accident Year 2019 [Member] Claims Development [Line Items] Claims Development [Line Items] Incurred Claims, Net of Reinsurance Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net Cumulative Paid Claims, Net of Reinsurance Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net Benefits payable, net of reinsurance Earnings Per Share [Abstract] EARNINGS PER COMMON SHARE COMPUTATION Earnings Per Share [Text Block] Property, Plant and Equipment [Abstract] Land Land Buildings and leasehold improvements Buildings and Improvements, Gross Equipment Machinery and Equipment, Gross Computer software Capitalized Computer Software, Gross Property and equipment, gross Property, Plant and Equipment, Gross Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property and equipment, net Property, Plant and Equipment, Net INCOME TAXES Income Tax Disclosure [Text Block] Estimate of Amortization Expense Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract] 2020 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2024 Finite-Lived Intangible Assets, Amortization Expense, Year Five Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Capital Loss Carryforward Capital Loss Carryforward [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Puerto Rico PUERTO RICO Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Increase in tax provision from remeasurement to deferred tax asset due to Tax Reform Law Tax Cuts and Jobs Act, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Repatriation tax for undistributed foreign earnings Tax Cuts And Jobs Act of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit) Tax Cuts And Jobs Act of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit) Decrease to tax provision from revisions of Tax Reform Law estimates Tax Cuts and Jobs Act, Measurement Period Adjustment, Income Tax Expense (Benefit) Benefit on sale of business Net operating losses to carryforward related to prior acquisitions Operating Loss Carryforwards Capital loss carryforward Tax Credit Carryforward, Amount Valuation allowances on net operating loss carryforwards related to prior acquisitions Deferred Tax Assets, Valuation Allowance Equity [Abstract] STOCKHOLDERS' EQUITY Stockholders' Equity Note Disclosure [Text Block] Quarterly Financial Information Disclosure [Abstract] Schedule of Quarterly Financial Information Quarterly Financial Information [Table Text Block] Leases [Abstract] Maturity of Lease Liabilities Lessee, Operating Lease, Liability, Payment, Due [Abstract] 2020 Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months 2021 Lessee, Operating Lease, Liability, Payments, Due Year Two 2022 Lessee, Operating Lease, Liability, Payments, Due Year Three 2023 Lessee, Operating Lease, Liability, Payments, Due Year Four 2024 Lessee, Operating Lease, Liability, Payments, Due Year Five After 2024 Lessee, Operating Lease, Liability, Payments, Due after Year Five Total lease payments Lessee, Operating Lease, Liability, Payments, Due Less: Interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Present value of lease liabilities Operating Lease, Liability Organization, Consolidation and Presentation of Financial Statements [Abstract] Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Premiums and services revenue Revenue, Product and Service Benchmark [Member] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Government Contracts Concentration Risk Government Contracts Concentration Risk [Member] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Federal government contracts Federal Government [Member] Federal Government [Member] CMS, coverage for individual Medicare Advantage members in Florida Federal Government, Centers For Medicare And Medicaid Services, Florida Medicare Advantage [Member] Federal Government, Centers For Medicare And Medicaid Services, Florida Medicare Advantage [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Premiums and services revenue (percent) Concentration Risk, Percentage Statement of Financial Position [Abstract] Receivables, allowance for doubtful accounts Accounts Receivable, Allowance for Credit Loss, Current Preferred stock, par (in USD per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, issued (in shares) Preferred Stock, Shares Issued Common stock, par (in USD 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) Common Stock, Shares, Issued Treasury stock (in shares) Treasury Stock, Shares Statement of Comprehensive Income [Abstract] Other comprehensive income (loss), net of tax Equity Method Investments and Joint Ventures [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Kindred at Home Kindred At Home [Member] Kindred At Home [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Balance sheets Equity Method Investment, Summarized Financial Information, Balance Sheet [Abstract] Equity Method Investment, Summarized Financial Information, Balance Sheet [Abstract] Current assets Equity Method Investment, Summarized Financial Information, Current Assets Non-current assets Equity Method Investment, Summarized Financial Information, Noncurrent Assets Current liabilities Equity Method Investment, Summarized Financial Information, Current Liabilities Non-current liabilities Equity Method Investment, Summarized Financial Information, Noncurrent Liabilities Shareholders' equity Equity Method Investment Summarized Financial Information, Equity Statements of income Equity Method Investment, Summarized Financial Information, Income Statement [Abstract] Revenues Equity Method Investment, Summarized Financial Information, Revenue Expenses Equity Method Investment, Summarized Financial Information, Cost of Sales Net income Equity Method Investment, Summarized Financial Information, Net Income (Loss) MEDICARE PART D Medicare Part D Disclosure [Text Block] Balance sheet amounts associated with Medicare Part D. Federal Current Federal Tax Expense (Benefit) States and Puerto Rico Current State and Local Tax Expense (Benefit) Total current provision Current Income Tax Expense (Benefit) Deferred expense Deferred Income Tax Expense (Benefit) SCHEDULE I - PARENT COMPANY FINANCIAL INFORMATION Condensed Financial Information of Parent Company Only Disclosure [Text Block] Fair Value Disclosures [Abstract] Schedule of Fair Value Measurements Fair Value, Assets Measured on Recurring Basis [Table Text Block] Accounting Policies [Abstract] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Healthcare Services Healthcare Services [Member] Healthcare Services [Member] Reporting Unit [Axis] Reporting Unit [Axis] Reporting Unit [Domain] Reporting Unit [Domain] Clinical Clinical [Member] Clinical [Member] Provider Provider [Member] Provider Goodwill [Line Items] Goodwill [Line Items] Fair value of reporting unit Reporting Unit, Fair Value Reporting Unit, Fair Value Carrying value of reporting unit Reporting Unit, Carrying Value Reporting Unit, Carrying Value Fair value in excess of carrying value Reporting Unit, Amount of Fair Value in Excess of Carrying Amount Fair value in excess of carrying value (percent) Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount Hypothetical goodwill impairment if 100 basis point increase in discount rate Hypothetical Goodwill Impairment, 100 Basis Point Increase In Discount Rate Hypothetical Goodwill Impairment, 100 Basis Point Increase In Discount Rate Goodwill Goodwill Goodwill impairment loss Goodwill, Impairment Loss Gross realized gains Debt Securities, Available-for-sale, Realized Gain Gross realized losses Debt Securities, Available-for-sale, Realized Loss Net realized capital gains Debt Securities, Available-for-sale, Realized Gain (Loss) Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Commercial paper Commercial Paper [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Maximum amount outstanding during period Short-term Debt, Maximum Amount Outstanding During Period Short-term debt outstanding Short-term Debt Weighted average annual interest rate (percent) Short-term Debt, Weighted Average Interest Rate, at Point in Time Healthcare Services Health And Well Being Services [Member] Health and Well-Being Services [Member] Goodwill [Roll Forward] Goodwill [Roll Forward] Beginning balance Acquisitions Goodwill, Acquired During Period Ending balance PROPERTY AND EQUIPMENT, NET Property, Plant and Equipment Disclosure [Text Block] Amortization expense for other intangible assets Amortization of Intangible Assets Impairment of intangible assets, finite-lived Impairment of Intangible Assets, Finite-lived Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Line of Credit Line of Credit [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Unsecured Revolving Credit Agreement Unsecured Revolving Credit Agreement Expires May 2022 [Member] Unsecured Revolving Credit Agreement Expires May 2022 [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Letter of Credit Letter of Credit [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] LIBOR London Interbank Offered Rate (LIBOR) [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt instrument term (in years) Debt Instrument, Term Basis points spread on variable rate (percent) Debt Instrument, Basis Spread on Variable Rate Facility fee (percent) Line of Credit Facility, Commitment Fee Percentage Debt to capitalization percentage, maximum Debt Instrument, Covenant, Debt To Capitalization Percentage, Maximum Debt Instrument, Covenant, Debt To Capitalization Percentage, Maximum Actual debt to capitalization percentage Debt Instrument, Covenant, Debt To Capitalization Percentage Debt Instrument, Covenant, Debt To Capitalization Percentage Maximum borrowing capacity including uncommitted incremental loan facility Line Of Credit Facility, Maximum Borrowing Capacity Including Uncommitted Incremental Capacity Maximum borrowing capacity under the credit facility including uncommitted incremental capacity and without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. Uncommitted incremental loan facility Line Of Credit Facility, Uncommitted Incremental Capacity Line Of Credit Facility, Uncommitted Incremental Capacity Line of credit, outstanding borrowings Line of Credit, Current Remaining borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Schedule of Balance Sheet Amounts Associated With Medicare Part D Balance Sheet Account Associated With Medicare Part D [Table Text Block] Balance Sheet Account Associated With Medicare Part D Amortized Cost Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost, Rolling Maturity [Abstract] Due within one year Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due after one year through five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Due after five years through ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Due after ten years Debt Securities, Available-for-sale, Allocated and Single Maturity Date, Maturity, after 10 Years, Amortized Cost Mortgage and asset-backed securities Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Amortized Cost Amortized Cost Debt Securities, Available-for-sale, Amortized Cost Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Due within one year Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due after one year through five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Due after five years through ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Due after ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value Mortgage and asset-backed securities Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value Fair Value Debt Securities, Available-for-sale GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill and Intangible Assets Disclosure [Text Block] SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Significant Accounting Policies [Text Block] REINSURANCE Reinsurance [Text Block] Reinsurance [Table] Reinsurance [Table] Reinsurance [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Protective Life Insurance Company Protective Life Insurance Company [Member] Protective Life Insurance Company [Member] All others All Others [Member] All Others Reinsurance Recoverables Reinsurance Recoverable Including Reinsurance Premium Paid [Member] Reinsurer Concentration Risk Reinsurer Concentration Risk [Member] Long-Duration Insurance Products [Axis] Long Duration Insurance Products [Axis] Long-Duration Insurance Products [Axis] Long-Duration Insurance Products [Domain] Long Duration Insurance Products [Domain] Long-Duration Insurance Products [Domain] 100% Coinsurance Agreements Coinsurance Agreement [Member] Coinsurance Agreement [Member] Effects of Reinsurance [Line Items] Effects of Reinsurance [Line Items] Reinsurance recoverables Reinsurance Recoverables, Including Reinsurance Premium Paid Percentage of coinsurance agreement Percentage Of Coinsurance Agreement Percentage Of Coinsurance Agreement Premiums ceded Ceded Premiums Written Benefits ceded Policyholder Benefits and Claims Incurred, Ceded Number of reinsurers comprising other reinsurance recoverables balance Number Of Reinsurers Comprising Other Reinsurance Recoverables Balance Number of reinsurers comprising other reinsurance recoverables balance Cash and securities in trusts held by certain reinsurers Amount Held In Cash And Securities In Trust At Least Equal To Recoverable From Reinsurer Amount held in cash and securities in trust, at least equal to the recoverable from the reinsurer EQUITY METHOD INVESTMENT Equity Method Investments and Joint Ventures Disclosure [Text Block] Schedule of Equity Method Investments Equity Method Investments [Table Text Block] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Investment securities Debt Securities, Available-for-sale, Current Receivables, less allowance for doubtful accounts of $69 in 2019 and $79 in 2018 Receivables, Net, Current Other current assets Other Assets, Current Total current assets Assets, Current Property and equipment, net Long-term investment securities Debt Securities, Available-for-sale, Noncurrent Equity method investment in Kindred at Home Equity Method Investments Other long-term assets Other Assets, Noncurrent Total assets Assets LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Benefits payable Trade accounts payable and accrued expenses Accounts Payable and Accrued Liabilities, Current Book overdraft Book Overdraft Liability Book Overdraft Liability Unearned revenues Contract with Customer, Liability, Current Short-term debt Debt, Current Total current liabilities Liabilities, Current Long-term debt Long-term Debt, Excluding Current Maturities Future policy benefits payable Liability for Future Policy Benefit, before Reinsurance Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 17) Commitments and Contingencies Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $1 par; 10,000,000 shares authorized; none issued Preferred Stock, Value, Issued Common stock, $0.16 2/3 par; 300,000,000 shares authorized; 198,629,992 shares issued at December 31, 2019 and 198,594,841 shares issued at December 31, 2018 Common Stock, Value, Issued Capital in excess of par value 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 Treasury stock, at cost, 66,524,771 shares at December 31, 2019 and 63,028,169 shares at December 31, 2018 Treasury Stock, Value Total stockholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders’ equity Liabilities and Equity Schedule of Maturity of Lease Liabilities Lessee, Operating Lease, Liability, Maturity [Table Text Block] Schedule of Rent Expense and Sublease Rental Income in Prior Years Schedule of Rent Expense [Table Text Block] Schedule of Future Annual Minimum Payments Due at Prior Year End Lessee, Operating Lease, Disclosure [Table Text Block] Equity securities Equity Securities, FV-NI Percentage of debt securities considered to be of investment-grade (percent) Percentage Of Total Debt Securities, Investment Grade Quality Percentage Of Total Debt Securities, Investment Grade Quality Maximum individual state general bond obligation as a percentage of total debt securities (percent) Maximum Individual State General Bond Obligation, As Percentage Of Total Debt Securities Maximum Individual State General Bond Obligation, As Percentage Of Total Debt Securities Securities in unrealized loss position, number of positions Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Securities, number of positions Debt, Securities, Available-For-Sale, Securities, Number of Positions Debt Securities, Available-for-sale, Securities, Number of Positions Other-than-temporary impairments Other than Temporary Impairment Losses, Investments Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Risk Corridor Settlement Risk Corridor Settlements Medicare Part D [Member] Risk Corridor Settlements - Medicare Part D [Member] CMS Subsidies/ Discounts Cms Subsidies Or Discounts [Member] CMS Subsidies Or Discounts [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Other current assets Trade accounts payable and accrued expenses Net current (liability) asset Net Current (Liability) Asset Net current (liability) asset Other long-term liabilities Net long-term liability Net Noncurrent Asset (Liability) Net Noncurrent Asset (Liability) Total net (liability) asset Net Asset (Liability) Net Asset (Liability) BENEFITS PAYABLE Insurance Disclosure [Text Block] Segment Reporting [Abstract] SEGMENT INFORMATION Segment Reporting Disclosure [Text Block] Operating right-of-use lease assets included within other long-term assets Operating Lease, Right-of-Use Asset Operating lease liabilities included within trade accounts payable and accrued expenses Operating Lease, Liability, Current Operating lease liabilities included within other long-term liabilities Operating Lease, Liability, Noncurrent Fixed operating lease costs Operating Lease, Cost Variable lease costs Variable Lease, Cost Sublease rental income Sublease Income Weighted average remaining lease term (in years) Operating Lease, Weighted Average Remaining Lease Term Weighted average discount rate (percent) Operating Lease, Weighted Average Discount Rate, Percent Operating lease cash payments Operating Lease, Payments Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2011 Plan 2011 Plan [Member] 2011 Plan 2019 Plan A2019 Plan [Member] A2019 Plan [Member] Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] Restricted Stock Restricted Stock [Member] Employee Stock Options Share-based Payment Arrangement, Option [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Employee retirement and savings plan cost Defined Contribution Plan, Cost Closing stock price (in USD per share) Closing Stock Price Closing stock price for the company per the New York Stock Exchange Percentage of retirement and savings plan's assets invested in our company common stock Percentage Of Retirement And Savings Plan S Assets Invested In Our Company Common Stock Percentage of retirement and savings plan's assets invested in our company common stock Shares of retirement and savings plans invested in company's common stock (in shares) Shares Of Retirement And Savings Plans Invested In Our Companys Common Stock Shares Of Retirement And Savings Plans Invested In Our Companys Common Stock Percentage of the retirement and savings plan's assets invested in our common stock as compared to company's outstanding shares at year-end Percentage Of Retirement And Savings Plan S Assets Invested In Our Common Stock As Compared To Company S Outstanding Shares At Year End Percentage of the retirement and savings plan's assets invested in our common stock as compared to company's outstanding shares at year-end Number of shares of our common stock reserved for issuance (in shares) Number Of Shares Of Our Common Stock Reserved For Issuance Under Our Defined Contribution Retirement Savings Plans Number of shares of our common stock reserved for issuance under our defined contribution retirement savings plans Combination of age and years necessary for retirement provision as related to our equity award program Combination Of Age And Years Necessary For Retirement Provision As Related To Our Equity Award Program Combination of age and years necessary for retirement provision as related to our equity award program Minimum age required for retirement eligibility as related to our equity award program Minimum Age Required For Retirement Eligibility As Related To Our Equity Award Program Minimum age required for retirement eligibility as related to our equity award program Minimum number of years of service for retirement eligibility as related to our equity award program Minimum Number Of Years Of Service For Retirement Eligibility As Related To Our Equity Award Program Minimum number of years of service for retirement eligibility as related to our equity award program Stock-based compensation modification expense Share-based Payment Arrangement, Plan Modification, Incremental Cost Limitations on deductibility of excess annual employee compensation as mandated by health insurance reforms Maximum Deductibility Of Annual Compensation Per Employee As Mandated By Health Reforms Maximum deductibility of annual compensation per employee as mandated by health insurance reform legislation. Employee service share based compensation tax benefit realized from exercise of stock options and restricted stock vesting Employee Service Share Based Compensation Tax Benefit Realized From Exercise Of Stock Options And Restricted Stock Vesting Disclosure of the aggregate tax benefit realized from the exercise of stock options and vesting of restricted stock Common stock shares reserved for stock award plans (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Shares available for future grants assuming all stock options or restricted stock are granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Vesting period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Weighted-average grant date fair value of restricted stock awards (in USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Percent of stock with performance-based conditions Share Based Compensation By Share Based Payment Award, Equity Instruments Other Than Options, Percent Of Stock With Performance Based Conditions Share Based Compensation By Share Based Payment Award, Equity Instruments Other Than Options, Percent Of Stock With Performance Based Conditions Fair value of shares vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Total compensation expense not yet recognized related to nonvested restricted stock Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Compensation expense over a weighted-average period (in years) Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Expiration period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Stratified homogeneous employee groups in stock option valuation Stock Option Valuation, Number of Homogeneous Employee Groups Stock Option Valuation, Number of Homogeneous Employee Groups Outstanding intrinsic value of stock options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Weighted-average remaining contractual term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Exercisable stock options intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Exercisable stock options weighted-average remaining contractual term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Total intrinsic value of stock options exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Proceeds from stock options exercised Proceeds from Stock Options Exercised Maturities of debt Long-term Debt, Fiscal Year Maturity [Abstract] 2020 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2021 Long-term Debt, Maturities, Repayments of Principal in Year Two 2022 Long-term Debt, Maturities, Repayments of Principal in Year Three 2023 Long-term Debt, Maturities, Repayments of Principal in Year Four 2024 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Schedule of Changes in Carrying Amount of Goodwill By Reportable Segments Schedule of Goodwill [Table Text Block] Schedule of Intangible Assets Included in Other Long-Term Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Estimate of Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table] Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table] Employee stock options Restricted stock Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] Net income available for common stockholders Weighted-average outstanding shares of common stock used to compute basic earnings per common share (in shares) Weighted Average Number of Shares Outstanding, Basic Dilutive effect of employee stock options and restricted stock (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Shares used to compute diluted earnings per common share (in shares) Weighted Average Number of Shares Outstanding, Diluted Basic earnings per common share (in USD per share) Earnings Per Share, Basic Diluted earnings per common share (in USD per share) Earnings Per Share, Diluted Number of antidilutive stock options and restricted stock awards excluded from computation (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount QUARTERLY FINANCIAL INFORMATION (Unaudited) Quarterly Financial Information [Text Block] 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] ASU 2016-02 Accounting Standards Update 2016-02 [Member] Services Service [Member] Reinsurance Policy, Type [Axis] Reinsurance Policy, Type [Axis] Reinsurance Policy [Domain] Reinsurance Policy [Domain] CMS reinsurance subsidies and discounts CMS Reinsurance Subsidies or Discounts [Member] CMS Reinsurance Subsidies or Discounts CMS brand name prescription drug discounts CMS Brand Name Prescription Drug Discounts [Member] CMS Brand Name Prescription Drug Discounts Regulatory Matters [Axis] Regulatory Matters [Axis] Regulatory Matters [Axis] Regulatory Matters [Domain] Regulatory Matters [Domain] Regulatory Matters [Domain] Health Care Reform Health Care Reform [Member] Health Care Reform [Member] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Equipment Equipment [Member] Computer Software Computer Software, Intangible Asset [Member] Building Building [Member] Tricare South Region Contract Tricare South Region Contract [Member] TRICARE South Region Contract [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Aetna Aetna Inc [Member] Aetna Inc [Member] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Merger breakup fee received Merger Breakup Fee Received Merger Breakup Fee Received Payment of annual health insurance industry fee Payment Of Annual Health Insurance Industry Fee Payment Of Annual Health Insurance Industry Fee Number of days notice for employer group to cancel short-duration prepaid health services policies Number Of Days Notice For Employer Group To Cancel Short Duration Prepaid Health Services Policies Number Of Days Notice For Employer Group To Cancel Short Duration Prepaid Health Services Policies Consumer discounts on brand name prescription drugs Consumer Discounts On Brand Name Prescription Drugs Beginning in 2011, the Health Reform Legislation mandates consumer discounts of 50% on brand name prescription drugs for Part D plan participants in the coverage gap. These discounts are funded by CMS and pharmaceutical manufacturers while we administer the application of these funds. Subsidy and discount payments Subsidy and Discount Payments Subsidy and Discount Payments Subsidy reimbursements Subsidy and Discount Reimbursements Subsidy and Discount Reimbursements Subsidy and discount payments in excess of reimbursements Subsidy and Discount Payments in Excess of Reimbursements Subsidy and Discount Payments in Excess of Reimbursements Settlement period after close Subsidy and Discounts, Settlement Period After Close Subsidy and Discounts, Settlement Period After Close TRICARE health care cost reimbursements Health Care Cost Reimbursements Reimbursements for health care cost payments associated with the TRICARE South Region contract TRICARE health care cost payments Health Care Cost Payments Health care cost payments associated with the TRICARE South Region contract Difference between TRICARE health care costs payments and reimbursements Health Care Cost Payments And Reimbursements Net The difference between health care cost payments and reimbursements related to the TRICARE South Region contract. Accounts receivable, net, current Accounts Receivable, after Allowance for Credit Loss, Current Bad-debt expense Accounts Receivable, Credit Loss Expense (Reversal) Contract with customer, asset, net Contract with Customer, Asset, after Allowance for Credit Loss Contract liabilities Contract with Customer, Liability Deferred costs Capitalized Contract Cost, Net Pharmaceutical rebates Accrued Pharmaceutical Rebates, Current Accrued Pharmaceutical Rebates, Current Typical term (in years) of short-duration employer-group prepaid health services policies Typical Term In Years Of Short Duration Employer Group Prepaid Health Services Policies Typical Term (In Years) Of Short-Duration Employer-Group Prepaid Health Services Policies Useful life Property, Plant and Equipment, Useful Life Lease liabilities Right-of-use assets Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Term loan and commercial paper Notes Payable To Banks And Commercial Paper [Member] Notes Payable To Banks And Commercial Paper [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Value Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Debt outstanding Debt Instrument, Fair Value Disclosure Short-term debt Schedule of Computation of Basic and Diluted Earnings Per Common Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Total revenues Revenues Income (loss) before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Shares Under Option Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Options outstanding, beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Options outstanding, ending balance (in shares) Options exercisable, ending balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Weighted-Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Options outstanding, beginning balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Granted (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Forfeited (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Options outstanding, ending balance (in dollars per share) Options exercisable, ending balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Favorable medical claims reserve development related to prior fiscal years Favorable Medical Claims Reserve Development Related To Prior Fiscal Years Favorable medical claims reserve development related to prior fiscal years Total IBNR Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount Cumulative number of reported claims Liability for Unpaid Claims and Claims Adjustment Expense, Cumulative Number Of Reported Claims Liability for Unpaid Claims and Claims Adjustment Expense, Cumulative Number Of Reported Claims Benefit expense reduction excluded from previous short duration benefits payable rollforward Liability for Future Policy Benefits, Period Expense (Income) SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Allowance for loss on receivables: SEC Schedule, 12-09, Allowance, Credit Loss [Member] Deferred tax asset valuation allowance: SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Balance at Beginning of Period SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount Acquired/(Disposed) Balances SEC Schedule, 12-09, Valuation Allowances and Reserves, Business Acquired Charged (Credited) to Costs and Expenses Valuation Allowances And Reserves, Charged Or Credited To Cost And Expense Amount of increase or (decrease) in valuation and qualifying accounts and reserves from charge or (credit) to cost and expense. Charged to Other Accounts Valuation Allowances And Reserves, Charged Or Credited To Other Accounts Amount of increase or (decrease) in valuation and qualifying accounts and reserves from charge or (credit) to accounts other than cost and expense. Deductions or Write-offs SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction Balance at End of Period LEASES Lessee, Operating Leases [Text Block] Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Nonvested restricted stock, beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Nonvested restricted stock, ending balance (in shares) Weighted- Average Grant-Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Nonvested restricted stock, beginning balance (in USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted (in USD per share) Vested (in USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Forfeited (in USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Nonvested restricted stock, ending balance (in USD per share) Cash dividends received from subsidiary SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees Aggregate statutory capital and surplus in our state regulated insurance subsidiaries Statutory Accounting Practices, Statutory Capital and Surplus, Balance Aggregate minimum regulatory requirements of statutory capital and surplus Statutory Accounting Practices, Statutory Capital and Surplus Required Dividends that may be paid to the parent company without prior approval by state regulatory authorities in 2014 Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval Dividends that were paid to the parent company without prior approval by state regulatory authorities Dividends To Parent Without Prior State Regulatory Approval Amount of dividends paid to our parent company without prior approval by state regulatory authorities Income Statement [Abstract] Revenues: Revenues [Abstract] Premiums Premiums Earned, Net Services Revenue from Contract with Customer, Including Assessed Tax Investment income Investment Income, Interest and Dividend Total revenues Operating expenses: Operating Expenses [Abstract] Benefits Policyholder Benefits and Claims Incurred, Net, Health Operating costs Selling, General and Administrative Expense Merger termination fee and related costs, net Merger Termination Fee And Related Costs, Net Merger Termination Fee And Related Costs, Net Depreciation and amortization Depreciation And Amortization Income Statement Depreciation and amortization expense excluding depreciation and amortization primarily from the delivery of pharmacy services by our wholly-owned pharmacy business (included in our Healthcare Services segment) which has been reclassified to benefit expenses. Total operating expenses Benefits, Losses and Expenses Income from operations Operating Income (Loss) Loss on sale of business Gain (Loss) on Disposition of Business Interest expense Interest Expense Other (income) expense, net Other Nonoperating Income (Expense) Income before income taxes and equity in net earnings Provision for income taxes Equity in net earnings of Kindred at Home Income (Loss) from Equity Method Investments Net income Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] U.S. Treasury and agency obligations US Treasury and Government [Member] Mortgage-backed securities Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Tax-exempt municipal securities Nontaxable Municipal Notes [Member] Residential mortgage-backed securities Residential Mortgage Backed Securities [Member] Commercial mortgage-backed securities Commercial Mortgage Backed Securities [Member] Asset-backed securities Asset-backed Securities [Member] Corporate debt securities Corporate Debt Securities [Member] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Amortized Cost to Fair Value Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract] Gross Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Fair Value INVESTMENT SECURITIES Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Stock-based compensation expense by type: Share-based Payment Arrangement, Noncash Expense [Abstract] Restricted stock Restricted Stock or Unit Expense Stock options Stock or Unit Option Plan Expense Total stock-based compensation expense Share-based Payment Arrangement, Noncash Expense Tax benefit recognized Share-based Payment Arrangement, Expense, Tax Benefit Stock-based compensation expense, net of tax Share-based Payment Arrangement, Expense, after Tax Number of reportable segments Number of Reportable Segments Member co-share amounts and government subsidies Government And Health Plan Member Subsidies Amount Amount of member co-share amounts and government subsidies that are excluded from benefits expense because the health plans do not bear responsibility. Depreciation and amortization classified as benefit expense Depreciation And Amortization Classified As Benefit Expense Depreciation and amortization expense that has been reclassified to be included with benefit expenses. The reclassification is the result of depreciation and amortization expense associated primarily from the delivery of pharmacy services by our wholly-owned pharmacy business included in our Healthcare Services segment. Schedule of Segment Reporting Information, By Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Class of Treasury Stock [Table] Class of Treasury Stock [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] February 2017 Authorization February 2017 Share Repurchase Authorization [Member] February 2017 Share Repurchase Authorization [Member] December 2017 Authorization December 2017 Share Repurchase Authorization [Member] December 2017 Share Repurchase Authorization [Member] July 2019 Authorization July 2019 Share Repurchase Authorization [Member] July 2019 Share Repurchase Authorization [Member] Excluding Employee Stock Plans and ASR Excluding Employee Stock Plans And Accelerated Share Repurchase Agreement [Member] Excluding Employee Stock Plans And Accelerated Share Repurchase Agreement Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Share repurchase authorization Stock Repurchase Program, Authorized Amount Shares repurchased (in shares) Treasury Stock, Shares, Acquired Cost of repurchases Treasury Stock, Value, Acquired, Cost Method Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Balances, beginning of period Less: Reinsurance recoverables Balances, beginning of period, net Liability for Unpaid Claims and Claims Adjustment Expense, Net Incurred related to: Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Current year Current Year Claims and Claims Adjustment Expense Prior years Prior Year Claims and Claims Adjustment Expense Total incurred Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Paid related to: Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract] Current year Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Prior years Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Total paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Reinsurance recoverable Balances, end of period Expected number of associates impacted Restructuring and Related Cost, Expected Number of Positions Eliminated Estimated charges Restructuring Charges Workforce optimization obligation Restructuring Reserve, Current REPORTING ENTITY Nature of Operations [Text Block] Business Combinations [Abstract] ACQUISITIONS AND DIVESTITURES Mergers, Acquisitions and Dispositions Disclosures [Text Block] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] WCAS Welsh Carson Anderson And Stowe [Member] Welsh Carson Anderson And Stowe [Member] MCCI Holdings LLC MCCI Holdings LLC [Member] MCCI Holdings LLC [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Enclara Enclara Healthcare [Member] Enclara Healthcare [Member] Family Physicians Group Family Physicians Group [Member] Family Physicians Group [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposed of by sale Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] KMG America Corporation KMG America Corporation [Member] KMG America Corporation [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Disclosures by Disposal Groups [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Cash consideration for acquisition Payments to Acquire Businesses, Gross Expected number of payor-agnostic, senior-focused primary care centers to be opened by strategic partnership Strategic Partnership Agreement, Expected Number Of Payor-Agnostic Senior-Focused Primary Care Centers Strategic Partnership Agreement, Expected Number Of Payor-Agnostic Senior-Focused Primary Care Centers Expected time frame for opening primary care centers Strategic Partnership Agreement, Expected Timeframe For Opening Primary Care Centers Strategic Partnership Agreement, Expected Timeframe For Opening Primary Care Centers Value of partnership entity Strategic Partnership Agreement, Value Of Partnership Entity Strategic Partnership Agreement, Value Of Partnership Entity Time frame for put and call option activity per partnership agreement, minimum Strategic Partnership Agreement, Timeframe For Put And Call Option Activity, Minimum Strategic Partnership Agreement, Timeframe For Put And Call Option Activity, Minimum Time frame for put and call option activity per partnership agreement, maximum Strategic Partnership Agreement, Timeframe For Put And Call Option Activity, Maximum Strategic Partnership Agreement, Timeframe For Put And Call Option Activity, Maximum Cash contribution from parent to disposal group to fund transaction Cash Contribution From Parent To Disposal Group To Fund Transaction Cash Contribution From Parent To Disposal Group To Fund Transaction Statutory capital transferred with sale Statutory Capital Transferred Upon Disposal Statutory Capital Transferred Upon Disposal Loss, including transaction costs, on disposal Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal Tax benefit on disposal transaction Disposal Group, Not Discontinued Operation, Tax Expense (Benefit) On Disposal Disposal Group, Not Discontinued Operation, Tax Expense (Benefit) On Disposal Cash transferred to third party prior to sale Cash Transferred To Third Party Prior To Sale Cash Transferred To Third Party Prior To Sale Disposal group revenues Disposal Group, Including Discontinued Operation, Revenue Disposal group income Disposal Group, Including Discontinued Operation, Operating Income (Loss) Note receivable Notes Receivable, Related Parties Purchase price allocated to goodwill Purchase price allocated to other intangible assets Finite-lived Intangible Assets Acquired Purchase price allocated to net tangible assets Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Tangible Assets Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Tangible Assets Estimated weighted average useful life of acquired intangible assets (in years) Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table] Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table] Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items] Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items] Fair Value Debt Securities, Available-for-sale, Sale [Abstract] Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months 12 months or more Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Total Debt Securities, Available-for-sale, Unrealized Loss Position Gross Unrealized Losses Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 12 months or more Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Accelerated Share Repurchases, Date [Axis] Accelerated Share Repurchases, Date [Axis] Accelerated Share Repurchases, Date [Domain] Accelerated Share Repurchases, Date [Domain] February 2017 ASR February 2017 Accelerated Share Repurchase Agreement [Member] February 2017 Accelerated Share Repurchase Agreement December 2017 ASR December 2017 Accelerated Share Repurchase Agreement [Member] December 2017 Accelerated Share Repurchase Agreement [Member] November 2018 ASR November 2018 Accelerated Share Repurchase Program [Member] November 2018 Accelerated Share Repurchase Program [Member] July 2019 ASR July 2019 Accelerated Share Repurchase Agreement [Member] July 2019 Accelerated Share Repurchase Agreement [Member] Accelerated share repurchase agreement amount Accelerated Share Repurchases, Agreement Amount Accelerated Share Repurchases, Agreement Amount Accelerated share repurchase payment Accelerated Share Repurchases, Settlement (Payment) or Receipt Shares received (in shares) Increase in treasury stock from share repurchases Decrease in capital in excess of par value Treasury Stock, Decrease In Capital In Excess Of Par Value Treasury Stock, Decrease In Capital In Excess Of Par Value Average daily volume weighted-average share price of common stock during term of agreement (in USD per share) Accelerated Share Repurchases, Final Price Paid Per Share Reclassification from capital in excess of par value to treasury stock Common Stock Reclassified From Capital In Excess Of Par Value To Treasury Stock Upon Repurchase, Value Common Stock Reclassified From Capital In Excess Of Par Value To Treasury Stock Upon Repurchase, Value Remaining share repurchase authorization at replacement Stock Repurchase Program, Remaining Authorized Repurchase Amount Expired Upon Replacement Stock Repurchase Program, Remaining Authorized Repurchase Amount Expired Upon Replacement Remaining authorized amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Common shares acquired in connection with employee stock plans (in shares) Share Repurchases Related To Employee Stock Based Compensation Awards Shares Number of shares of common stock that were repurchased in the administration of our employee share-based compensation plans. Under the terms of these plans, we accept shares of common stock from option holders if they elect to surrender previously-owned shares upon exercise of the option to cover the exercise price of the options or, in the case of restricted shares of common stock, the withholding of shares to satisfy tax withholding obligations associated with the vesting of such shares. Common shares acquired in connection with employee stock plans, amount Share Repurchases Related To Employee Stock Based Compensation Awards Value Cost of common stock that were repurchased in the administration of our employee share-based compensation plans. Under the terms of these plans, we accept shares of common stock from option holders if they elect to surrender previously-owned shares upon exercise of the option to cover the exercise price of the options or, in the case of restricted shares of common stock, the withholding of shares to satisfy tax withholding obligations associated with the vesting of such shares. Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Capital In Excess of Par Value Additional Paid-in Capital [Member] Retained Earnings Retained Earnings [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Treasury Stock Treasury Stock [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balances Balances (in shares) Shares, Issued Other comprehensive income (loss) Other Comprehensive Income (Loss), Net Of Tax, Portion Attributable To Parent, Including Equity Method Investments Other Comprehensive Income (Loss), Net Of Tax, Portion Attributable To Parent, Including Equity Method Investments Common stock repurchases Dividends and dividend equivalents Dividends, Common Stock, Cash Stock-based compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Restricted stock unit vesting Stock Issued During Period, Value, Restricted Stock Award, Gross Restricted stock unit vesting (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross Stock option exercises Stock Issued During Period, Value, Stock Options Exercised Stock option exercises (in shares) Stock Issued During Period, Shares, New Issues, Common Shares For Exercise Of Stock Options Stock Issued During Period, Shares, New Issues, Common Shares For Exercise Of Stock Options Balances Balances (in shares) Receivable from operating subsidiaries Accounts Receivable, Related Parties, Current Investments in subsidiaries Investment In Related Parties And Subsidiaries Investment in related parties and subsidiaries. LIABILITIES AND STOCKHOLDERS' EQUITY Payable to operating subsidiaries Accounts Payable, Related Parties Current portion of notes payable to operating subsidiaries Notes Payable, Related Parties, Current Book overdraft Other Short-term Borrowings Other current liabilities Other Liabilities, Current Commitments and contingencies Management fees charged to operating subsidiaries Management Fees Charged To Operating Subsidiaries Through intercompany service agreements approved, if required, by state regulatory authorities, Humana Inc., our parent company, charges a management fee for reimbursement of certain centralized services provided to its subsidiaries, including information systems, disbursement, investment and cash administration, marketing, legal, finance, and medical and executive management oversight Investment and other income, net Investment And Other Income Net Investment and other income, net Expenses: Depreciation Depreciation Interest Total operating expenses Costs and Expenses Other expense, net (Loss) income before income taxes and equity in net earnings of subsidiaries Income (Loss) Before Income Taxes and Equity in Net Earnings Of Subsidiaries Income (Loss) Before Income Taxes and Equity in Net Earnings Of Subsidiaries (Benefit) provision for income taxes (Loss) income before equity in net earnings of subsidiaries Income Loss Before Equity In Net Earnings Of Subsidiaries Income (loss) before equity in net earnings of subsidiaries Equity in net earnings of subsidiaries Equity In Net Earnings Of Subsidiaries Equity in net earnings of subsidiaries Loss Contingencies [Table] Loss Contingencies [Table] Scenario [Axis] Scenario [Axis] Scenario [Domain] Scenario [Domain] Forecast Forecast [Member] Medicare Medicare [Member] Medicare [Member] Military services Military Service [Member] Military Service [Member] Medicaid Medicaid [Member] Medicaid [Member] Tricare East Region Contract Tricare East Region Contract [Member] Tricare East Region Contract [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Purchase obligations in 2020 Unrecorded Unconditional Purchase Obligation, Due in Next Twelve Months Purchase obligations in 2021 Unrecorded Unconditional Purchase Obligation, Due within Two Years Purchase obligations in 2022 Unrecorded Unconditional Purchase Obligation, Due within Three Years Purchase obligations in 2023 Unrecorded Unconditional Purchase Obligation, Due within Four Years Purchase obligations in 2024 Unrecorded Unconditional Purchase Obligation, Due after Five Years Percentage of premiums and services revenue Percentage Of Total Premium And Services Revenues Percentage Of Total Premium And Services Revenues Percentage of risk score calculated from claims submitted through EDS Percentage Of Risk Score Calculated From Claims Submitted Through EDS Percentage Of Risk Score Calculated From Claims Submitted Through EDS Number of states comprising TRICARE beneficiaries Number Of States Comprising TRICARE Beneficiaries Number Of States Comprising TRICARE Beneficiaries Number of TRICARE beneficiaries Number Of TRICARE Beneficiaries Number Of TRICARE Beneficiaries Contract term years Contract Term Years Contract term, years. Litigation recoveries sought Gain Contingency, Recovery Sought Gain Contingency, Recovery Sought Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Options Option on Securities [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 3 fair value measurement Fair Value, Inputs, Level 3 [Member] Measurement Input Type [Axis] Measurement Input Type [Axis] Measurement Input Type [Domain] Measurement Input Type [Domain] Annualized volatility Measurement Input, Option Volatility [Member] Secured credit rate Measurement Input, Secured Credit Rate [Member] Measurement Input, Secured Credit Rate [Member] Long-term net operating profit after tax Measurement Input, Net Operating Profit After Tax [Member] Measurement Input, Net Operating Profit After Tax [Member] Weighted average cost of capital Measurement Input, Discount Rate [Member] Long term growth rate Measurement Input, Long-term Revenue Growth Rate [Member] Option Indexed to Issuer's Equity [Axis] Option Indexed to Issuer's Equity [Axis] Option Indexed to Issuer's Equity, Type [Domain] Option Indexed to Issuer's Equity, Type [Domain] Put option Put Option [Member] Call option Call Option [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other long-term liabilities Other Noncurrent Liabilities [Member] Other long-term assets Other Noncurrent Assets [Member] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair value of financial liability Financial Liabilities Fair Value Disclosure Fair value of financial asset Financial Assets, Fair Value Disclosure Financial Assets, Fair Value Disclosure Significant unobservable inputs Derivative Asset (Liability) Net, Measurement Input Senior notes Senior Notes [Member] Term note Notes Payable to Banks [Member] $400 million, 2.625% due October 1, 2019 2.625 Percent Senior Notes Due October 2019 [Member] 2.625 Percent Senior Notes Due October 2019 [Member] $400 million, 2.50% due December 15, 2020 2.50 Percent Senior Notes Due December 2020 [Member] 2.50 Percent Senior Notes Due December 2020 [Member] $600 million, 3.15% due December 1, 2022 3.15 Percent Senior Notes Due December 2022 [Member] 3.15 Percent Senior Notes Due December 2022 [Member] $400 million, 2.90% due December 15, 2022 2.90 Percent Senior Notes Due December 2022 [Member] 2.90 Percent Senior Notes Due December 2022 [Member] $600 million, 3.85% due October 1, 2024 3.85 Percent Senior Notes Due October 2024 [Member] 3.85 Percent Senior Notes Due October 2024 [Member] $600 million, 3.95% due March 15, 2027 3.95 Percent Senior Notes Due March 2027 [Member] 3.95 Percent Senior Notes Due March 2027 [Member] $500 million, 3.125% due August 15, 2029 A 3.125 Percent Senior Notes Due August 2029 [Member] A 3.125 Percent Senior Notes Due August 2029 [Member] $250 million, 8.15% due June 15, 2038 8.15 Percent Senior Notes Due June 2038 [Member] 8.15 Percent Senior Notes Due June 2038 [Member] $400 million, 4.625% due December 1, 2042 4.625 Percent Senior Notes Due December 2042 [Member] 4.625 Percent Senior Notes Due December 2042 [Member] $750 million, 4.95% due October 1, 2044 4.95 Percent Senior Notes Due October 2044 [Member] 4.95 Percent Senior Notes Due October 2044 [Member] $400 million, 4.80% due March 15, 2047 4.80 Percent Senior Notes Due March 2047 [Member] 4.80 Percent Senior Notes Due March 2047 [Member] $500 million, 3.95% due August 15, 2049 A 3.95 Percent Senior Notes Due August 2049 [Member] A 3.95 Percent Senior Notes Due August 2049 [Member] Face amount Debt Instrument, Face Amount Stated interest rate (percent) Debt Instrument, Interest Rate, Stated Percentage Long-term debt, current maturities Long-term Debt, Current Maturities Total short-term debt Long-term debt Rent Expense and Sublease Rental Income Operating Leases, Rent Expense, Net [Abstract] Rent expense Operating Leases, Rent Expense Sublease rental income Operating Leases, Income Statement, Sublease Revenue Net rent expense Operating Lease Rental Expenses Net Operating Lease Rental Expenses Net FAIR VALUE Fair Value Disclosures [Text Block] Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Other Businesses Segment Reconciling Items [Member] Eliminations/Corporate Corporate And Eliminations [Member] Corporate And Eliminations [Member] Individual Commercial Individual Commercial Segment [Member] Individual Commercial Segment [Member] Products Product [Member] Individual Medicare Advantage Medicare Advantage [Member] Medicare Advantage [Member] Group Medicare Advantage Group Medicare Advantage [Member] Group Medicare Advantage Medicare stand-alone PDP Medicare Stand Alone Prescription Drug Plan [Member] Medicare Stand Alone Prescription Drug Plan [Member] Total Medicare Fully-insured Fully Insured [Member] Fully Insured [Member] Specialty Specialty [Member] Specialty [Member] Medicaid and other Medicaid And Other [Member] Medicaid and Other [Member] Provider ASO and other A S O And Other [Member] ASO and Other [Member] Pharmacy Pharmacy [Member] Pharmacy Services revenue Total external revenues Revenues, Premiums And Service, External Revenues, Premiums And Service, External Intersegment revenues Revenues, Intersegment Revenues, Intersegment Segment earnings Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Cash and cash equivalents Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents Receivables, net Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net Investment securities Disposal Group, Including Discontinued Operation, Debt Securities, Available-For-Sale Disposal Group, Including Discontinued Operation, Debt Securities, Available-For-Sale Other assets Disposal Group, Including Discontinued Operation, Other Assets Total assets disposed Disposal Group, Including Discontinued Operation, Assets Benefits payable Disposal Group, Including Discontinued Operation, Liability For Claims And Claims Adjustment Expense Disposal Group, Including Discontinued Operation, Liability For Claims And Claims Adjustment Expense Trade accounts payable and accrued expenses Disposal Group, Including Discontinued Operation, Accounts Payable and Accrued Liabilities Future policy benefits payable Disposal Group, Including Discontinued Operation, Liability For Future Policy Benefits Disposal Group, Including Discontinued Operation, Liability For Future Policy Benefits Total liabilities disposed Disposal Group, Including Discontinued Operation, Liabilities Depreciation expense Amortization expense for capitalized internally developed and purchased software Capitalized Computer Software, Amortization Debt redemption price (percent) Debt Instrument, Redemption Price, Percentage Proceeds from issuance of debt, net Proceeds from Debt, Net of Issuance Costs Repayment of short-term debt Repayment of long-term debt Loss on extinguishment of debt Gain (Loss) on Extinguishment of Debt 2018 Term Note Term Note November 2018 [Member] Term Note November 2018 [Member] 2020 Term Loan Commitment Term Loan Agreement February 2020 [Member] Term Loan Agreement February 2020 [Member] Federal Funds Rate Fed Funds Effective Rate Overnight Index Swap Rate [Member] Extension period term (in years) Debt Instrument, Extension Period Term Debt Instrument, Extension Period Term Base rate component, basis spread on variable rate (percent) Debt Instrument, Component Of Base Rate, Basis Spread On Variable Rate Debt Instrument, Component Of Base Rate, Basis Spread On Variable Rate Number of draws on term loan commitment allowable per agreement Debt Instrument, Number Of Draws On Loan Commitment Per Agreement Debt Instrument, Number Of Draws On Loan Commitment Per Agreement Minimum draw amount on term loan commitment allowable per agreement Debt Instrument, Minimum Draw On Loan Commitment Per Agreement Debt Instrument, Minimum Draw On Loan Commitment Per Agreement Unused commitment threshold for expiration Debt Instrument, Unused Commitment Threshold For Expiration Event Debt Instrument, Unused Commitment Threshold For Expiration Event Schedule of Activity in Benefits Payable Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Schedule of Favorable Medical Claims Reserve Development Related to Prior Fiscal Years by Segment Schedule Of Favorable Medical Claims Reserve Development Related To Prior Fiscal Years By Segment [Table Text Block] Schedule Of Favorable Medical Claims Reserve Development Related To Prior Fiscal Years By Segment Schedule of Incurred and Paid Claims Development Short-duration Insurance Contracts, Claims Development [Table Text Block] Schedule of Reconciliation of Net Incurred and Paid Claims to Benefits Payable Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Table Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Loss on sale of business Net realized capital gains Equity in net earnings of Kindred at Home Stock compensation Amortization Provision for deferred income taxes Increase (Decrease) in Deferred Income Taxes Changes in operating assets and liabilities, net of effect of businesses acquired and dispositions: Increase (Decrease) in Operating Capital [Abstract] Receivables Increase (Decrease) in Receivables Other assets Increase (Decrease) in Other Operating Assets Benefits payable Increase (Decrease) in Health Care Insurance Liabilities Other liabilities Increase (Decrease) in Other Operating Liabilities Unearned revenues Increase (Decrease) in Contract with Customer, Liability Other Other Operating Activities, Cash Flow Statement Net cash provided by operating activities Cash flows from investing activities Cash transferred in sale of business Cash Divested from Deconsolidation Purchases of property and equipment Proceeds from sales of investment securities Cash flows from financing activities (Receipts) withdrawals from contract deposits, net Increase (Decrease) in Other Deposits Repayment of long-term debt Proceeds from stock option exercises & other Supplemental cash flow disclosures: Supplemental Cash Flow Information [Abstract] Interest payments Interest Paid, Excluding Capitalized Interest, Operating Activities Income tax payments, net Income Taxes Paid, Net Details of businesses acquired in purchase transactions: Payments to Acquire Businesses, Net of Cash Acquired [Abstract] Fair value of assets acquired, net of cash acquired Fair Value of Assets Acquired Less: Fair value of liabilities assumed Liabilities Assumed Cash paid for acquired businesses, net of cash acquired Provision for Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Provision for Income Taxes Using Federal Statutory Rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Principal Components of Net Deferred Tax Balances Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Equity method investment ownership (percent) Equity Method Investment, Ownership Percentage Purchase of equity method investment Equity method investment Purchase price allocated to put options Equity Method Investment, Purchase Price Allocation, Financial Liability Equity Method Investment, Purchase Price Allocation, Financial Liability Purchase price allocated to call options Equity Method Investment, Purchase Price Allocation, Financial Asset Equity Method Investment, Purchase Price Allocation, Financial Asset (Income) expense on put and call options Derivative, Gain (Loss) on Derivative, Net Schedule of Assets and Liabilities Disposed Disposal Groups, Including Discontinued Operations [Table Text Block] Schedule of Carrying Value of Debt Outstanding Schedule of Debt [Table Text Block] Schedule of Maturities of Long-term Debt Schedule of Maturities of Long-term Debt [Table Text Block] Compensation and other accrued expense Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Benefits Benefits payable Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Loss Reserves Net operating loss carryforward Deferred Tax Assets, Operating Loss Carryforwards Deferred acquisition costs Deferred Tax Assets Deferred Policy Acquisition Cost Portion of deferred tax balance as it relates to deferred acquisition costs Unearned revenues Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Unearned Premiums Reserve Other Deferred Tax Assets, Other Capital loss carryforward Deferred Tax Assets, Capital Loss Carryforwards Investment securities Deferred Tax Assets, Investments Total deferred income tax assets Deferred Tax Assets, Gross Valuation allowance Total deferred income tax assets, net of valuation allowance Deferred Tax Assets, Net of Valuation Allowance Depreciable property and intangible assets Deferred Tax Liabilities Depreciable Property And Intangible Assets Portion of deferred tax balance as it relates to depreciable property and intangible assets Investment securities Deferred Tax Liabilities, Investments Prepaid expenses Deferred Tax Liabilities, Prepaid Expenses Future policy benefits payable Deferred Tax Liabilities, Future Policy Benefits Payable Deferred Tax Liabilities, Future Policy Benefits Payable Total deferred income tax liabilities Deferred Tax Liabilities, Gross Total net deferred income tax liabilities Deferred Tax Liabilities, Net EMPLOYEE BENEFIT PLANS Disclosure Of Compensation Related Costs Share Based Payments And Compensation And Retirement Disclosure [Text Block] Disclosure Of Compensation Related Costs Share Based Payments And Compensation And Retirement Disclosure [Text Block] Schedule of Property and Equipment Property, Plant and Equipment [Table Text Block] Cover page. Document Type Document Type Document Annual Report Document Annual Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Title of 12(b) Security Title of 12(b) Security Trading Symbol Trading Symbol Security Exchange Name Security Exchange Name Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Health Care Reform Health Care Reform [Policy Text Block] Health Care Reform Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Investment Securities Investment, Policy [Policy Text Block] Receivables and Revenue Recognition Receivable [Policy Text Block] Other Current Assets Other Current Assets [Policy Text Block] Other Current Assets Policy Acquisition Costs Acquisition Costs Policy [Policy Text Block] Describes an insurance entity's accounting policy for deferred policy acquisition costs, including the nature and amount of capitalized costs incurred to write or acquire insurance contracts, and the basis for and methodologies applied in capitalizing and amortizing such costs. Long-Lived Assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Equity Method Investments Equity Method Investments [Policy Text Block] Goodwill and Definite-Lived Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Benefits Payable and Benefits Expense Recognition Benefits Payable And Benefit Expense Recognition Policy [Policy Text Block] Describes the entity's accounting policies, methodologies, and assumptions for estimating its liability as of the balance sheet date for the cost of settling reported and unreported claims. Future policy benefits payable Future Policy And Benefits Payable Policy [Policy Text Block] Description of policies associated with the accounting treatment of future policy benefits payable Book Overdraft Book Overdraft Policy [Policy Text Block] Description of policies associated with the accounting treatment of book overdraft Income Taxes Income Tax, Policy [Policy Text Block] Stock-Based Compensation Compensation Related Costs, Policy [Policy Text Block] Earnings Per Common Share Earnings Per Share, Policy [Policy Text Block] Fair Value Fair Value of Financial Instruments, Policy [Policy Text Block] Recently Issued Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Minimum Lease Payments Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Sublease Rental Receipts Future Minimum Sublease Rentals, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract] 2019 Future Minimum Sublease Rentals, Sale Leaseback Transactions, Next Twelve Months 2020 Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Two Years 2021 Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Three Years 2022 Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Four Years 2023 Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Five Years Thereafter Future Minimum Sublease Rentals, Sale Leaseback Transactions, Thereafter Total Future Minimum Sublease Rentals, Sale Leaseback Transactions Net Lease Commitments Net Lease Commitments [Abstract] Net Lease Commitments [Abstract] 2019 Net Operating Lease Commitment Within Year One This element represents the total net lease commitments within the first year following the balance sheet date. 2020 Net Operating Lease Commitment Within Year Two This element represents the total net lease commitments within the second year following the balance sheet date. 2021 Net Operating Lease Commitment Within Year Three This element represents the total net lease commitments within the third year following the balance sheet date. 2022 Net Operating Lease Commitment Within Year Four This element represents the total net lease commitments within the fourth year following the balance sheet date. 2023 Net Operating Lease Commitment Within Year Five This element represents the total net lease commitments within the fifth year following the balance sheet date. Thereafter Net Operating Lease Commitment Thereafter This element represents the total net lease commitments after the fifth year following the balance sheet date. Total Net Operating Lease Commitment Total This element represents the total net lease commitments existing as of the balance sheet date. Schedule of Details of Dividend Payments Schedule Of Dividends Declared And Paid Table [Table Text Block] Tabular disclosure of all or some of the information related to dividends declared and paid Class of Treasury Stock Class of Treasury Stock [Table Text Block] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Line Items] Class of Stock [Line Items] Dividends Dividends, Common Stock [Abstract] Amount per Share (in USD per share) Common Stock, Dividends, Per Share, Cash Paid Total Amount Dividends Cash dividend declared (in USD per share) Common Stock, Dividends, Per Share, Declared Individual Commercial Individual Commercial [Member] Individual Commercial [Member] (Favorable) unfavorable medical claims reserve development Weighted-average fair value at grant date (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Expected option life (years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected volatility (percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Risk-free interest rate at grant date (percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Dividend yield (percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Measurement Basis [Axis] Measurement Frequency [Axis] Fair Value Measurement [Domain] Measurement Frequency [Domain] Recurring Basis Fair Value, Recurring [Member] Quoted Prices in Active Markets (Level 1) Fair Value, Inputs, Level 1 [Member] Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Unobservable Inputs (Level 3) Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Debt securities Common stock Total invested assets Assets, Fair Value Disclosure