Leases [Abstract] Operating lease expense Operating Lease, Cost Finance lease expense: Finance Lease, Liability, Payment, Due [Abstract] Amortization of ROU assets Finance Lease, Right-of-Use Asset, Amortization Interest on lease liabilities Finance Lease, Interest Expense Total finance lease expense Finance Lease, Cost Finance Lease, Cost Accounting Policies [Abstract] Cash and cash equivalents Schedule of Cash and Cash Equivalents [Table Text Block] Restricted cash and cash equivalents Restrictions on Cash and Cash Equivalents [Table Text Block] Summarized premium revenue Revenue from External Customers by Geographic Areas [Table Text Block] Amounts due to government agencies Reserves Reported to Other Agencies [Table Text Block] Quality incentive premium revenue recognized Quality Incentive Premium Revenue Recognized [Table Text Block] Quality incentive premium revenue recognized. Income Tax Disclosure [Abstract] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] State State and Local Jurisdiction [Member] Foreign Foreign Tax Authority [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Change in tax rate, deferred tax asset, income tax expense (benefit) Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense Measurement period adjustment, income tax expense (benefit) Tax Cuts and Jobs Act, Measurement Period Adjustment, Income Tax Expense (Benefit) Operating loss carryforwards Operating Loss Carryforwards Tax credit carryovers Tax Credit Carryforward, Amount Deferred tax assets Tax Credit Carryforward, Valuation Allowance Decrease in deferred tax asset valuation allowance Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Valuation allowance Deferred Tax Assets, Valuation Allowance Impact on effective tax rate if tax benefits are recognized Unrecognized Tax Benefits that Would Impact Effective Tax Rate Liability for unrecognized tax benefits, potential decrease Decrease in Unrecognized Tax Benefits is Reasonably Possible Equity [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Award Type [Domain] Award Type [Domain] RSAs, PSAs and PSUs (defined below) Restricted and Performance Stock [Member] Restricted and Performance Stock [Member] Employee stock purchase plan and stock options Employee Stock Purchase Plan and Stock Options [Member] Employee Stock Purchase Plan and Stock Options [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Pretax Charges Share-based Payment Arrangement, Expense Net-of-Tax Amount Share-based Payment Arrangement, Expense, after Tax Restructuring settled without cash Share-based Payment Arrangement, Accelerated Cost Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Furniture and equipment Furniture and Fixtures [Member] Software Computer Software, Intangible Asset [Member] Leasehold improvements Leasehold Improvements [Member] Building and improvements Building and Building Improvements [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Useful life of property plant and equipment Property, Plant and Equipment, Useful Life Unrecognized tax benefits roll forward Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Gross unrecognized tax benefits at beginning of period Unrecognized Tax Benefits Increases in tax positions for current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Increases in tax positions for prior years Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Decreases in tax positions for prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Lapse in statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Gross unrecognized tax benefits at end of period Medicaid program: Medicaid Program [Abstract] Medicaid Program [Abstract] Medical cost floors and corridors Amounts Due to Government Agencies, Medical Cost Floors and Corridors Amounts Due to Government Agencies, Medical Cost Floors and Corridors Other amounts due to states Amounts Due to Government Agencies, Amounts Due State Amounts Due to Government Agencies, Amounts Due State Marketplace program: Marketplace Program [Abstract] Marketplace Program [Abstract] Risk adjustment Amounts Due to Government Agencies, Risk Adjustment Amounts Due to Government Agencies, Risk Adjustment Cost sharing reduction Amounts Due to Government Agencies, Cost Sharing Reduction Amounts Due to Government Agencies, Cost Sharing Reduction Other Amounts Due to Government Agencies, Other Amounts Due to Government Agencies, Other Total Medical Premium Liability Due To Agency Medical Premium Liability Due to Agency Investments, Debt and Equity Securities [Abstract] Investments Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Contractual maturities of investments Investments Classified by Contractual Maturity Date [Table Text Block] Available-for-sale investments Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block] Balances of restricted investments Restrictions On Investments [Table Text Block] Restrictions On Investments [Table Text Block] RSAs Restricted Stock [Member] PSAs Performance Shares [Member] PSUs Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested, shares beginning of period (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 Unvested, shares end of period (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] Unvested, beginning balance (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 (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 Vested (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 (USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Unvested, ending balance (USD per share) Summary of property and equipment and depreciation and amortization recognized Property, Plant and Equipment [Table Text Block] Statement of Cash Flows [Abstract] Statement [Table] Statement [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Call Option Call Option, Derivative Asset [Member] Call Option, Derivative Asset [Member] Conversion Option Embedded Derivative Financial Instruments [Member] Statement [Line Items] Statement [Line Items] Operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income (loss) Net Income (Loss) Attributable to Parent Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Deferred income taxes Increase (Decrease) in Deferred Income Taxes Share-based compensation Share-based Payment Arrangement, Noncash Expense Amortization of convertible senior notes and finance lease liabilities Amortization Of Debt Discount (Premium) And Sale Leaseback Financing Obligation Amortization of Debt Discount (Premium) and Sale Leaseback Financing Obligation (Gain) loss on debt extinguishment Gain (Loss) on Extinguishment of Debt Loss on sales of subsidiaries, net of gain Gain (Loss) on Disposition of Business Non-cash restructuring charges Non-cash Restructuring Charges Non-cash Restructuring Charges Impairment losses Goodwill and Intangible Asset Impairment Other, net Other Operating Activities, Cash Flow Statement Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Receivables Increase (Decrease) in Receivables Prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Medical claims and benefits payable Increase (Decrease) in Health Care Insurance Liabilities Amounts due government agencies Increase (Decrease) In Medical Premium Liability Due To Agency Increase (Decrease) in Medical Premium Liability Due to Agency Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Deferred revenue Increase (Decrease) in Contract with Customer, Liability Income taxes Increase (Decrease) in Income Taxes Payable Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of investments Payments to Acquire Marketable Securities Proceeds from sales and maturities of investments Proceeds from Sale and Maturity of Marketable Securities Purchases of property, equipment and capitalized software Payments to Acquire Property, Plant, and Equipment Net cash received from sale of subsidiaries Proceeds from Divestiture of Interest in Subsidiaries and Affiliates Other, net Payments for (Proceeds from) Other Investing Activities Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Repayment of principal amount of convertible senior notes Repayments of Convertible Debt Cash paid for partial settlement of conversion option Cash Paid For Settlement Of Conversion Option Cash Paid For Settlement Of Conversion Option Cash received for partial settlement of call option Proceeds from Convertible Debt Cash paid for partial termination of warrants Payments for Repurchase of Warrants Proceeds from borrowings under term loan facility Proceeds from Long-term Lines of Credit Common stock purchases Payments for Repurchase of Common Stock Repayment of credit facility Repayments of Lines of Credit Proceeds from senior notes offerings, net of issuance costs Proceeds from Issuance of Debt Proceeds from borrowings under credit facility Proceeds from Lines of Credit Other, net Proceeds from (Payments for) Other Financing Activities Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Net (decrease) increase in cash and cash equivalents, and restricted cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents, and restricted 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 Supplemental cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid during the period for: Cash Paid During The Period [Abstract] Cash Paid During The Period [Abstract] Income taxes Income Taxes Paid, Net Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Schedule of non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Common stock issued in exchange for convertible senior notes Notes Issued Component of convertible senior notes allocated to additional paid-in capital, net of income taxes Notes Issued, Fair Value Adjustment Increase (Decrease) Notes Issued, Fair Value Adjustment Increase (Decrease) Net increase to additional paid-in capital Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature Common stock used for stock-based compensation Stock Issued Common stock purchases not settled at end of period Common Stock Purchases Not Settled At End Of Period Common Stock Purchases Not Settled At End Of Period Details of sales of subsidiaries: Proceeds from Divestiture of Interest in Subsidiaries and Affiliates [Abstract] Decrease in carrying amount of assets Increase (Decrease) in Carrying Amount of Assets Increase (Decrease) in Carrying Amount of Assets Decrease in carrying amount of liabilities Gain (Loss) on Disposition of Liabilities Gain (Loss) on Disposition of Liabilities Transaction costs Disposition of Business, Transaction Costs Disposition of Business, Transaction Costs Cash received from buyers Disposition of Business, Receivable from Buyer Disposition of Business, Receivable from Buyer Loss on sale of subsidiaries, net of gain Details of change in fair value of derivatives, net: Details of change in fair value of derivatives [Abstract] Details of change in fair value of derivatives Change in fair value of derivatives, net Derivative, Gain (Loss) on Derivative, Net Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] Statutory federal tax (benefit) rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent State income provision (benefit), net of federal Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Nondeductible health insurer fee (“HIF”) Effective Income Tax Rate Reconciliation, Nondeductible Expense, Health Insurance, Percent Effective Income Tax Rate Reconciliation, Nondeductible Expense, Health Insurance, Percent Nondeductible compensation Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Payment Arrangement, Percent Nondeductible goodwill impairment Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Percent Worthless stock deduction Effective Income Tax Rate Reconciliation, Worthless Stock Deduction Effective Income Tax Rate Reconciliation, Worthless Stock Deduction Revaluation of net deferred tax assets Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Effective tax expense (benefit) rate Effective Income Tax Rate Reconciliation, Percent Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Segment Reporting [Abstract] Operating segment information Schedule of Segment Reporting Information, by Segment [Table Text Block] Debt Disclosure [Abstract] 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] Senior Notes Senior Notes [Member] Term Loan Facility Line of Credit [Member] Convertible Debt Convertible Debt [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 5.375% Notes Senior Notes Due 2022 [Member] Senior Notes Due 2022 [Member] 4.875% Notes 4.875% Senior Notes [Member] 4.875% Senior Notes [Member] Term Loan Facility Term Loan [Member] Term Loan [Member] 1.125% Convertible Notes Cash Convertible Senior Notes due 2020 [Member] Cash Convertible Senior Notes due 2020 [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Percentage of contractual interest rate Debt Instrument, Interest Rate, Stated Percentage Net carrying amount Long-term Debt, Gross 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 Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Operating lease term Operating Lease, Remaining Lease Term Operating Lease, Remaining Lease Term Operating lease renewal term Lessee, Operating Lease, Renewal Term Operating leases, weighted average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Finance lease term Finance Lease, Remaining Lease Term Finance Lease, Remaining Lease Term Finance lease renewal term Lessee, Finance Lease, Renewal Term Finance leases, weighted average remaining lease term Finance Lease, Weighted Average Remaining Lease Term Operating leases, weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Finance leases, weighted average discount rate Finance Lease, Weighted Average Discount Rate, Percent Rent expense Operating Leases, Rent Expense Stock based compensation expense Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block] Restricted and performance stock activity Schedule of Nonvested Share Activity [Table Text Block] Stock options, activity Share-based Payment Arrangement, Option, Activity [Table Text Block] Stock option plans, by exercise price range Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block] Recorded in depreciation and amortization: Recorded In Depreciation And Amortization [Abstract] Recorded In Depreciation And Amortization [Abstract] Amortization of capitalized software Depreciation And Amortization Of Capitalized Software Depreciation, and amortization of capitalized software. Depreciation and amortization of furniture, equipment, building, and improvements Depreciation Amortization of intangible assets Amortization of Intangible Assets Amortization of finance leases Subtotal Depreciation and Amortization, Continuing Operations Depreciation and Amortization, Continuing Operations Recorded in cost of service revenue: Recorded In Cost Of Service Revenue [Abstract] Recorded In Cost Of Service Revenue [Abstract] Amortization of capitalized software and deferred contract costs Cost, Amortization Total depreciation and amortization recognized Cost, Depreciation and Amortization Interest cost recognized for the period relating to the: Interest Costs Incurred [Abstract] Contractual interest coupon rate Interest Expense, Debt, Excluding Amortization Amortization of the discount Amortization of Debt Discount (Premium) Total interest cost recognized Interest Expense, Debt Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] Receivables [Abstract] Receivables Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] 1.125% Conversion Option 1.125% Conversion Option Term Loan Facility Revolving Credit Facility [Member] 1.125% Convertible Notes 5.375% Notes 4.875% Notes Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Carrying Amount 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] 1.125% Conversion Option derivative liability Derivative Liability Estimated fair values of long-term debt Debt Instrument, Fair Value Disclosure Percentage of contractual interest rate on derivative Derivative, Fixed Interest Rate Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Health Plans Health Plans [Member] Health plans. Other Other Segments [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Total revenue Revenues Margin Gross Profit Goodwill and intangible assets, net Intangible Assets, Net (Including Goodwill) Total assets Assets Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Class of Warrant or Right [Axis] Class of Warrant or Right [Axis] Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] 1.125% Warrants Cash Convertible Senior Notes Due 2020, Warrants [Member] Cash Convertible Senior Notes Due 2020, Warrants [Member] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2019 EIP Equity Incentive Plan [Member] Equity Incentive Plan [Member] 2019 ESPP Employee Stock Purchase Plan [Member] Employee stock purchase plan. Stock options Share-based Payment Arrangement, Option [Member] Employee Stock Purchase Plan Employee Stock [Member] Common stock authorized Stock Repurchase Program, Authorized Amount Repurchased of common stock (in shares) Stock Repurchased During Period, Shares Repurchased of common stock Stock Repurchased During Period, Value Average cost (USD per share) Treasury Stock Acquired, Average Cost Per Share Stated interest rate Class Of Warrant Or Right, Stated Interest Rate Class Of Warrant Or Right, Stated Interest Rate Number of warrants issued (in shares) Debt Conversion, Converted Instrument, Warrants or Options Issued Striking price of warrants (USD per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Class of warrant Class of Warrant or Right, Outstanding Cash paid for partial termination of 1.125% Warrants Number of warrants terminated (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Terminated, Number Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Terminated, Number Number of shares issued under ESPP (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Maximum award vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Unrecognized compensation expense Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Weighted average period of unrecognized compensation expense Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Unrecognized compensation forfeited rate Unrecognized Compensation Forfeited Rate Unrecognized compensation forfeited rate. Stock option expiration period Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Weighted average grant date fair value of stock options granted (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Risk free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected volatility rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected term of awards Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Options exercised, intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Employee purchase price as a percentage of stock price Fair Market Value Of Common Stock Percentage Fair market value of common stock, Percentage. Maximum annual contribution per employee Share Based Compensation Arrangement By Share Based Payment Award Maximum Amount Per Employee Share based compensation arrangement by share based payment award maximum amount per employee. Risk-free interest rate, minimum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum Risk-free interest rate, maximum Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum Minimum expected volatility rate inputs for fair value measurement Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Maximum expected volatility rate inputs for fair value measurement Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Common stock issued during period (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Share-based compensation (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Consolidation and Presentation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Investments Investment, Policy [Policy Text Block] Long-Lived Assets Property, Plant and Equipment, Policy [Policy Text Block] Intangible Assets Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Leases Lessee, Leases [Policy Text Block] Goodwill and Business Combinations Business Combinations Policy [Policy Text Block] Premium Revenue - Health Plans Revenue [Policy Text Block] Medical Care Costs - Health Plans Health Care Costs, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Taxes Based on Premiums Taxes Based On Premiums [Policy Text Block] Taxes based on premiums. Concentrations of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Risks and Uncertainties Risks And Uncertainties [Policy Text Block] Risks and uncertainties. Recent Accounting Pronouncements Adopted and Not Yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Receivables Receivable [Policy Text Block] Earnings Per Share [Abstract] Summary of denominators for the computation of basic and diluted earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Amortized Cost Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract] Due in one year or less 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 Amortized Cost Debt Securities, Available-for-sale, Amortized Cost Estimated Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Due in one year or less 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 Estimated Fair Value Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value 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] Condensed Balance Sheets Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Investments Marketable Securities, Current Receivables Receivables, Net, Current Due from affiliates Related Party Transaction, Due from (to) Related Party, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Derivative asset Derivative Asset, Current Total current assets Assets, Current Property, equipment, and capitalized software, net Property, Plant and Equipment, Net Investments in subsidiaries Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Deferred income taxes Deferred Income Tax Assets, Net Advances to related parties and other assets Advances To Related Parties And Other Assets Advances to related parties and other assets. Total assets LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Medical claims and benefits payable Liability for Claims and Claims Adjustment Expense Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Current portion of long-term debt Long-term Debt and Lease Obligation, Current Derivative liability Derivative Liability, Current Total current liabilities Liabilities, Current Long-term debt Long-term Debt, Excluding Current Maturities Finance lease liabilities Finance Lease, Liability, Noncurrent Finance lease liabilities Capital Lease Obligations, Noncurrent Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, $0.001 par value; 150 million shares authorized; outstanding: 62 million shares at each of December 31, 2019, and December 31, 2018 Common Stock, Value, Outstanding Preferred stock, $0.001 par value; 20 million shares authorized, no shares issued and outstanding Preferred Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) Total stockholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders’ equity Liabilities and Equity Insurance [Abstract] Schedule of liability for unpaid claims and claims adjustment expense Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Components of the change in medical claims and benefits payable Components Of Change In Medical Claims And Benefits Payable [Table Text Block] Components Of Change In Medical Claims And Benefits Payable [Table Text Block] Incurred and paid claims development Short-duration Insurance Contracts, Claims Development [Table Text Block] Reconciliation of claims development to liability Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Table Text Block] Schedule of Condensed Financial Statements [Table] Condensed Statements of Income Income Statement [Abstract] Revenue: Revenues [Abstract] Administrative services fees Insurance Agency Management Fee Investment income and other revenue Interest and Dividend Income, Operating Total revenue Expenses: Operating Expenses [Abstract] General and administrative expenses General and Administrative Expense Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Other operating expenses Policyholder Benefits and Claims Incurred, Net, Health Restructuring costs Restructuring Costs Impairment losses Total operating expenses Costs and Expenses Gain (loss) on sales of subsidiaries Operating income (loss) Operating Income (Loss) Interest expense Interest Expense Other (income) expense, net Other Nonoperating Income (Expense) Loss before income tax (benefit) expense and equity in net earnings (losses) of subsidiaries Income (Loss) Before Income Taxes And Equity In Net Income Of Subsidiaries Income (Loss) Before Income Taxes And Equity In Net Income Of Subsidiaries Income tax expense (benefit) Income Tax Expense (Benefit) Net loss before equity in net earnings (losses) of subsidiaries Net Income (Loss) From Continuing Operations Before Equity Method Investments, Extraordinary Items, Noncontrolling Interest Net Income (Loss) From Continuing Operations Before Equity Method Investments, Extraordinary Items, Noncontrolling Interest Equity in net earnings (losses) of subsidiaries Income (Loss) from Subsidiaries, Net of Tax Net income (loss) Quarterly Financial Information Disclosure [Abstract] Quarterly Results of Operations (Unaudited) Quarterly Financial Information [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 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, Address Line Two Entity Address, Address Line Two 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] Entity Central Index Key Entity Central Index Key Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Current Fiscal Year End Date Current Fiscal Year End Date Debt Long-term Debt [Text Block] Postemployment Benefits [Abstract] Maximum matching contribution by employer under defined contribution plan Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Expense recognized in connection with contributions Defined Contribution Plan, Cost Deferred compensation plan deferral percentage of basic salary Deferred Compensation Plan Deferral Percentage Of Basic Salary Deferred compensation plan deferral percentage of basic salary. Deferred compensation plan deferral percentage of bonus Deferred Compensation Plan Deferral Percentage Of Bonus Deferred compensation plan deferral percentage of bonus. Common stock, par value (dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares outstanding Common Stock, Shares, Outstanding Preferred stock, par value (dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Medical Claims and Benefits Payable Short-Duration Insurance and Deposit Contracts [Text Block] Summary of accounts receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] 1.125% Convertible Notes 4.875% Notes Convertible Senior Notes Convertible Senior Notes Due 2044 [Member] Convertible Senior Notes Due 2044 [Member] Percentage of contractual interest rate on notes Repayments of debt Repayments of Debt Repayments of principal Debt Instrument, Periodic Payment, Principal Repayment of aggregate carrying amount Debt Instrument, Periodic Payment (Gain) loss on debt extinguishment Net carrying amount of debt Debt instrument, conversion ratio Debt Instrument, Convertible, Conversion Ratio Debt instrument conversion price per share (in dollars per share) Debt Instrument, Convertible, Conversion Price Senior note effective interest rate Debt Instrument, Interest Rate, Effective Percentage Senior notes amortization period Debt Instrument, Convertible, Remaining Discount Amortization Period If-converted value in excess of principal on convertible debt Debt Instrument, Convertible, If-converted Value in Excess of Principal Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Medical claims and benefits payable, beginning balance Components of medical care costs related to: Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Current period Current Year Claims and Claims Adjustment Expense Prior periods Prior Year Claims and Claims Adjustment Expense Total medical care costs Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Change in non-risk and other provider payables Medical Claims And Benefits Payable, Adjustments, Change In Provider Medical Claims and Benefits Payable, Adjustments, Change in Provider Payments for medical care costs related to: Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract] Current period Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Prior periods Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Total paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Medical claims and benefits payable, ending balance Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Table] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] CMS Subsidies CMS Subsidies [Member] CMS Subsidies [Member] Liability for Claims and Claims Adjustment Expense [Line Items] Liability for Claims and Claims Adjustment Expense [Line Items] Disposal group, operating expense Disposal Group, Including Discontinued Operation, Operating Expense Operating Leases 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 Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Subtotal - undiscounted lease payments Lessee, Operating Lease, Liability, Payments, Due Less imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Total operating lease liabilities Operating Lease, Liability Finance Leases 2020 Finance Lease, Liability, Payments, Due Next Twelve Months 2021 Finance Lease, Liability, Payments, Due Year Two 2022 Finance Lease, Liability, Payments, Due Year Three 2023 Finance Lease, Liability, Payments, Due Year Four 2024 Finance Lease, Liability, Payments, Due Year Five Thereafter Finance Lease, Liability, Payments, Due after Year Five Subtotal - undiscounted lease payments Finance Lease, Liability, Payment, Due Less imputed interest Finance Lease, Liability, Undiscounted Excess Amount Total finance lease liabilities Finance Lease, Liability Schedule of Product Information [Table] Schedule of Product Information [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] Benefit Year 2017 Short-duration Insurance Contracts, Accident Year 2017 [Member] Benefit Year 2018 Short-duration Insurance Contracts, Accident Year 2018 [Member] Benefit Year 2019 Short-Duration Insurance Contract, Accident Year 2019 [Member] Product Information [Line Items] Product Information [Line Items] Incurred Claims and Allocated Claims Adjustment Expenses Incurred Claims and Allocated Claims Adjustment Expenses Liability For Unpaid Claims And Claims Adjustment Expense, Incurred Claims Including Acquisition Adjustment Liability For Unpaid Claims And Claims Adjustment Expense, Incurred Claims Including Acquisition Adjustment Total IBNP Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount Cumulative number of reported claims (in claim) Short-duration Insurance Contract, Cumulative Number of Reported Claims Provision for income taxes Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) Total current Current Income Tax Expense (Benefit) Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Foreign Deferred Foreign Income Tax Expense (Benefit) Total deferred Deferred Income Tax Expense (Benefit) Income tax expense (benefit) Leases Lessee, Operating Leases [Text Block] Leases Lessee, Finance Leases [Text Block] 5.375% Senior Notes Aggregate principal amount of notes outstanding Debt Instrument, Face Amount Statement of Stockholders' Equity [Abstract] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Retained Earnings Retained Earnings [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance (in shares) Shares, Outstanding Beginning Balance Common stock purchases Exchange of convertible senior notes (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Exchange of convertible senior notes Other comprehensive income (loss), net Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Share-based compensation Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Adoption of new accounting standards Cumulative Effect of New Accounting Principle in Period of Adoption Partial termination of warrants Adjustments to Additional Paid in Capital, Other Conversion of convertible senior notes Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt Ending Balance (in shares) Ending Balance Incurred claims and allocated claims adjustment expenses Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net Less: cumulative paid claims and allocated claims adjustment expenses Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net All outstanding liabilities before 2017 Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Outstanding Liabilities Relating to Prior Years Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Outstanding Liabilities Relating to Prior Years Non-risk and other provider payables Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Aggregate Reconciling Items Total Accrued expenses and reserve liabilities Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Other accrued medical costs Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Net operating losses Deferred Tax Assets, Operating Loss Carryforwards Fixed assets and intangibles Deferred Tax Asset, Fixed Assets and Intangibles Deferred Tax Asset, Fixed Assets and Intangibles Unearned premiums Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Unearned Premiums Reserve Lease financing obligation Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Deferred Rent Tax credit carryover Deferred Tax Assets, Tax Credit Carryforwards Other Deferred Tax Assets, Other Valuation allowance Total deferred income tax assets, net of valuation allowance Deferred Tax Assets, Net of Valuation Allowance Prepaid expenses Deferred Tax Liabilities, Prepaid Expenses Other Deferred Tax Liabilities, Other Total deferred income tax liabilities Deferred Tax Liabilities, Gross Net deferred income tax asset Deferred Tax Assets, Net Restructuring and Related Activities [Abstract] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Restructuring Plan [Axis] Restructuring Plan [Axis] Restructuring Plan [Domain] Restructuring Plan [Domain] IT Restructuring IT Restructuring [Member] IT Restructuring [Member] 2017 Restructuring Plan 2017 Restructuring Plan [Member] 2017 Restructuring Plan [Member] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] One-Time Termination Benefits One-time Termination Benefits [Member] Consulting Fees Professional Services Fees [Member] Professional Services Fees [Member] Contract Termination Contract Termination [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Cumulative restructuring costs Restructuring and Related Cost, Cost Incurred to Date Decrease to estimated expected costs remaining Restructuring and Related Cost, Expected Cost Accrued liabilities under restructuring plan Restructuring Reserve Other restructuring costs Other Restructuring Costs Payments for restructuring Payments for Restructuring Restructuring costs Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets, Net Goodwill and Intangible Assets Disclosure [Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] 1.125% Call Option 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] Fair value of restricted shares granted Share-Based Compensation Arrangement By Share-Based Payment Award, Equity Instruments Other Than Options, Granted In Period, Fair Value Share-Based Compensation Arrangement By Share-Based Payment Award, Equity Instruments Other Than Options, Granted In Period, Fair Value Fair value of restricted shares vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Fee-for-service claims incurred but not paid (“IBNP”) Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Paid (IBNP), Fee-for-service Claims, Amount Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Paid (IBNP), Fee-for-service Claims, Amount Pharmacy payable Pharmacy Claims Payable Pharmacy Claims Payable Capitation payable Capitation Claims Payable Capitation Claims Payable Other Other Claims Payable Other Claims Payable Cash and cash equivalents Restricted cash and cash equivalents, non-current Restricted Cash, Noncurrent Restricted cash and cash equivalents, current Restricted Cash, Current Total cash, cash equivalents, and restricted cash and cash equivalents presented in the consolidated statements of cash flows Summary of quarterly results of operations Quarterly Financial Information [Table Text Block] Term Loan Facility Term Loan Facility Current portion of long-term debt Long-Term Debt, Current Maturities, Net Of Unamortized Premium (Discount) Long-Term Debt, Current Maturities, Net Of Unamortized Premium (Discount) Lease financing obligations Capital Lease Obligations, Current Debt issuance costs Debt Issuance Costs, Current, Net Total, current portion Non-current portion of long-term debt Long-Term Debt, Noncurrent, Net Of Unamortized Debt Discount Long-Term Debt, Noncurrent, Net Of Unamortized Debt Discount Debt issuance costs Debt Issuance Costs, Noncurrent, Net Total, non-current portion Operating leases: Lessee, Operating Lease, Description [Abstract] ROU assets Operating Lease, Assets, Lessee [Abstract] Operating Lease, Assets, Lessee [Abstract] Other assets Operating Lease, Right-of-Use Asset Lease liabilities Operating Lease, Liabilities, Lessee [Abstract] Operating Lease, Liabilities, Lessee [Abstract] Accounts payable and accrued liabilities (current) Operating Lease, Liability, Current Other long-term liabilities (non-current) Operating Lease, Liability, Noncurrent Total operating lease liabilities Finance leases: Lessee, Finance Lease, Description [Abstract] ROU assets Finance Lease, Assets, Lessee [Abstract] Finance Lease, Assets, Lessee [Abstract] Property, equipment, and capitalized software, net Finance Lease, Right-of-Use Asset Lease liabilities Finance Lease, Liabilities, Lessee [Abstract] Finance Lease, Liabilities, Lessee [Abstract] Accounts payable and accrued liabilities (current) Finance Lease, Liability, Current Finance lease liabilities (non-current) Total finance lease liabilities Net Income (Loss) Per Share Earnings Per Share [Text Block] Medical claims and benefits payable Medical Claims And Benefits Payable Medical Claims and Benefits Payable Favorable (unfavorable) adjustment Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Components of lease expense and supplemental consolidated cash flow information Lease, Cost [Table Text Block] Supplemental lease information Assets And Liabilities, Lessee [Table Text Block] Assets And Liabilities, Lessee [Table Text Block] Operating lease maturities Lessee, Operating Lease, Liability, Maturity [Table Text Block] Finance lease maturities Finance Lease, Liability, Maturity [Table Text Block] Cash used in operating activities: Operating leases Operating Lease, Payments Finance leases Finance Lease, Interest Payment on Liability Cash used in financing activities: Finance leases Finance Lease, Principal Payments ROU assets recognized in exchange for lease obligations: Right-of-Use Asset Obtained in Exchange for Operating Lease Liability [Abstract] Right-of-Use Asset Obtained in Exchange for Operating Lease Liability [Abstract] Operating leases Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Finance leases Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Cash and cash equivalents Property, equipment, and capitalized software, net Property, Plant, And Equipment And Finance Lease Right-Of-Use Asset, After Accumulated Depreciation And Amortization Property, Plant, And Equipment And Finance Lease Right-Of-Use Asset, After Accumulated Depreciation And Amortization Property, equipment, and capitalized software, net Goodwill and intangible assets, net Restricted investments Restricted Investments, Noncurrent Other assets Other Assets, Noncurrent Amounts due government agencies Deferred revenue Contract with Customer, Liability, Current Long-term debt Finance lease liabilities Other long-term liabilities Common stock, $0.001 par value per share; 150 million shares authorized; outstanding: 62 million shares at each of December 31, 2019, and December 31, 2018 Preferred stock, $0.001 par value per share; 20 million shares authorized, no shares issued and outstanding Additional paid-in capital Accumulated other comprehensive income (loss) Net income per share - Basic (in dollars per share) Earnings Per Share, Basic Net income per share - Diluted (in dollars per share) Earnings Per Share, Diluted Debt Securities, Held-to-maturity [Table] Debt Securities, Held-to-maturity [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Florida FLORIDA New Mexico NEW MEXICO Ohio OHIO Puerto Rico PUERTO RICO Other Other Geographical Areas [Member] Other Geographical Areas. Schedule of Held-to-maturity Securities [Line Items] Schedule of Held-to-maturity Securities [Line Items] Statement of Comprehensive Income [Abstract] Net income (loss) Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Unrealized investment income (loss) Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax Less: effect of income taxes Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Other comprehensive income (loss), net of tax Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Line of Credit Facility [Table] Line of Credit Facility [Table] Term Loan Facility Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Credit Facility Letter of Credit Letter of Credit [Member] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Minimum principal amount of advancements Line of Credit Facility, Minimum Threshold for Advancements Line of Credit Facility, Minimum Threshold for Advancements Amortization payment percentage Line of Credit Facility, Amortization Payment Percentage Line of Credit Facility, Amortization Payment Percentage Aggregate principal amount of notes outstanding Current borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Amount outstanding under Letter of Credit Long-term Line of Credit Maximum available quality incentive premium - current period Maximum Available Quality Incentive Premium Current Year Maximum available quality incentive premium current year. Amount of quality incentive premium revenue recognized in current period: Amount Of Quality Incentive Premium Revenue Recognized In Current Period [Abstract] Amount Of Quality Incentive Premium Revenue Recognized In Current Period [Abstract] Earned current period Amount Of Current Year Quality Incentive Premium Revenue Recognized Amount of current year quality incentive premium revenue recognized. Earned prior periods Amount Of Quality Incentive Premium Revenue Recognized From Prior Year Amount of quality incentive premium revenue recognized from prior year. Total quality incentive premium revenue recognized Quality Incentive Premium Revenue Recognized Quality incentive premium revenue recognized. Quality incentive premium revenue recognized as a percentage of total premium revenue Quality Incentive Premium Revenue As A Percentage Of Total Revenue Quality Incentive Premium Revenue As A Percentage Of Total Revenue Restructuring Costs Restructuring and Related Activities Disclosure [Text Block] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Schedule of goodwill Schedule of Goodwill [Table Text Block] Summary of identified intangible assets, by major class Schedule of Finite-Lived Intangible Assets [Table Text Block] Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Corporate debt securities Corporate Debt Securities [Member] Mortgage-backed securities Commercial Mortgage Backed Securities [Member] Asset-backed securities Asset-backed Securities [Member] U.S. Treasury notes US Treasury Notes Securities [Member] Municipal securities Municipal Securities [Member] Municipal securities. GSEs US Government-sponsored Enterprises Debt Securities [Member] Foreign securities Debt Security, Government, Non-US [Member] Certificates of deposit Certificates of Deposit [Member] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] 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 Estimated Fair Value Debt Securities, Available-for-sale Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Health Plans California CALIFORNIA Florida Illinois ILLINOIS Michigan MICHIGAN New Mexico Ohio South Carolina SOUTH CAROLINA Texas TEXAS Washington WASHINGTON Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Premium revenue Premiums Earned, Net Premium revenue percentage Health Care Organization, Revenue Percentage Health Care Organization, Revenue Percentage Number of reportable segments Number of Reportable Segments Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Corporate debt securities Mortgage-backed securities Collateralized Mortgage Backed Securities [Member] Asset-backed securities Municipal securities GSEs Estimated Fair Value Debt Securities, Available-For-Sale, Unrealized Loss Position [Abstract] Debt Securities, Available-For-Sale, Unrealized Loss Position [Abstract] In a Continuous Loss Position for Less than 12 Months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months In a Continuous Loss Position for 12 Months or More Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Unrealized Losses Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] In a Continuous Loss Position for Less than 12 Months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss In a Continuous Loss Position for 12 Months or More Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total Number of Positions Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract] In a Continuous Loss Position for Less than 12 Months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions In a Continuous Loss Position for 12 Months or More Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Beginning balance, outstanding (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, Gross Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Ending balance, outstanding (in shares) Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Beginning balance, outstanding (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Granted (usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Exercised (usd per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Ending balance, outstanding (usd per share) Outstanding, Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Outstanding, Weighted Average Remaining Contractual term Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Stock options exercisable and expected to vest (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Stock options exercisable and expected to vest (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Exercisable (usd per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Exercisable, Aggregate Intrinsic Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Exercisable, Weighted Average Remaining Contractual term Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Provision for income taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Effective income tax rate reconciliation to the statutory federal income tax rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Significant components of deferred tax assets and liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Unrecognized tax benefits roll forward Summary of Income Tax Contingencies [Table Text Block] Numerator: Net Income (Loss) Attributable to Parent [Abstract] Denominator: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Shares outstanding at the beginning of the period (in shares) Weighted-average number of shares issued: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Exchange of convertible senior notes (in shares) Weighted Average Number of Shares Issued, Basic Conversion of convertible senior notes (in shares) Weighted Average Number of Shares Issued, Conversion of Senior Notes Weighted Average Number of Shares Issued, Conversion of Senior Notes Stock-based compensation (in shares) Weighted Average Number of Shares, Share Based Compensation Weighted Average Number of Shares, Share Based Compensation Denominator for basic net income (loss) per share (in shares) Weighted Average Number of Shares Outstanding, Basic Effect of dilutive securities: Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] Warrants (in shares) Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants Convertible senior notes (in shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Share-based compensation (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Denominator for diluted net (loss) income per share (in shares) Weighted Average Number of Shares Outstanding, Diluted Net income (loss) per share: Earnings Per Share, Basic and Diluted [Abstract] Basic (in dollars per share) Diluted (in dollars per share) 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] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Warrants Warrant [Member] Convertible senior notes Convertible Senior Notes [Member] Convertible Senior Notes [Member] 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] Potentially dilutive common shares excluded from calculations (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Stock-based compensation (in shares) Antidilutive Securities Excluded from Computation of EPS, Share Based Compensation, Amount Antidilutive Securities Excluded from Computation of EPS, Share Based Compensation, Amount 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 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Corporate debt securities Mortgage-backed securities Asset-backed securities U.S. Treasury notes Municipal securities Government-sponsored enterprise securities (“GSEs”) Foreign securities Certificates of deposit 1.125% Call Option derivative asset Derivative Financial Instruments, Assets [Member] Fair value of assets measured on recurring basis Assets, Fair Value Disclosure [Abstract] Debt securities, available-for-sale 1.125% Call Option derivative asset Derivative Asset Total assets Assets, Fair Value Disclosure Total liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure Percentage of contractual interest rate on derivative Capitalized software Software and Software Development Costs [Member] Furniture and equipment Building and improvements Land Land [Member] Total cost Property, Plant and Equipment, Gross Less: accumulated amortization - capitalized software Capitalized Computer Software, Accumulated Amortization Less: accumulated depreciation and amortization - furniture, equipment, building, and improvements Property, Plant, and Equipment, Owned, Accumulated Depreciation Total accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment ROU assets - finance leases Property, equipment, and capitalized software, net Property, equipment, and capitalized software, net Commitments and Contingencies Disclosure [Abstract] Statutory Accounting Practices [Table] Statutory Accounting Practices [Table] Statutory Accounting Practices [Line Items] Statutory Accounting Practices [Line Items] Aggregate statutory capital and surplus Statutory Accounting Practices, Statutory Capital and Surplus, Balance Required minimum statutory capital surplus Statutory Accounting Practices, Statutory Capital and Surplus Required Net assets of subsidiaries subject to restrictions Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries Cash, cash equivalents, and investments Cash, Cash Equivalents, and Short-term Investments Share-based Payment Arrangement, Option, Exercise Price Range [Table] Share-based Payment Arrangement, Option, Exercise Price Range [Table] Exercise Price Range [Axis] Exercise Price Range [Axis] Exercise Price Range [Domain] Exercise Price Range [Domain] $33.02 Exercise Price Range 1 [Member] Exercise Price Range 1 [Member] $67.33 Exercise Price Range 2 [Member] Exercise Price Range 2 [Member] Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] Share-based Payment Arrangement, Option, Exercise Price Range [Line Items] Options Outstanding, Number Outstanding Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding Options Outstanding, Weighted Average Remaining Contractual Life (Years) Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term Options Outstanding, Weighted-Average Exercise Price Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Exercise Price Options Exercisable, Number Exercisable Share-based Payment Arrangement, Option, Exercise Price Range, Shares Exercisable Options Exercisable, Weighted-Average Exercise Price Share-based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Exercise Price Basis Of Presentation [Table] Basis Of Presentation [Table] Basis Of Presentation [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] NextLevel Health Partners, Inc. NextLevel Health Partners, Inc. [Member] NextLevel Health Partners, Inc. [Member] YourCare Health Plan YourCare Health Plan, Inc. [Member] YourCare Health Plan, Inc. [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Texas Health and Human Services Commission, STARPLUS Program Texas Health And Human Services Commission, STAR PLUS Program [Member] Texas Health And Human Services Commission, STAR PLUS Program [Member] STAR/CHIP Contracts STAR/CHIP Contracts [Member] STAR/CHIP Contracts [Member] Scenario [Axis] Scenario [Axis] Scenario [Domain] Scenario [Domain] Forecast Forecast [Member] Texas New York NEW YORK Basis Of Presentation [Line Items] Basis Of Presentation [Line Items] Basis Of Presentation [Line Items] Number of reportable segments Number of states in which company operates (in state) Number of States in which Entity Operates Number of members eligible for the health care programs Number Of Members Eligible For The Health Care Programs Number of members eligible for the health care programs. Minimum contract terms Minimum Contract Term Minimum contract term. Maximum contract term Maximum Contract Term Maximum contract term. Contract term Contract Term Contract Term Number of members served, approximately (in member) Health Care Organization, Number Of Members Health Care Organization, Number of Members Premium revenue Purchase price of assets Business Combination, Consideration Transferred Number of countries Number Of Counties In Which Entity Operates Number Of Counties In Which Entity Operates Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Medical care costs Health Care, Premium [Member] Cost of service revenue Technology Service [Member] Revenue: Premium tax revenue Health Care Organization, Premium Tax Revenue Health Care Organization, Premium Tax Revenue Health insurer fees reimbursed Health Care Organization, Insurer Fee Revenue Health Care Organization, Insurer Fee Revenue Service revenue Insurance Services Revenue Operating expenses: Costs and Expenses [Abstract] Cost of revenue Cost of Goods and Services Sold Premium tax expenses Premium Tax Expenses An assessment levied by a state government on the net premium income collected. Health insurer fees Health Care Organization, Insurer Fee Expense Health Care Organization, Insurer Fee Expense Loss on sales of subsidiaries, net of gain Other expenses, net: Other Income and Expenses [Abstract] Other (income) expenses, net Total other expenses, net Nonoperating Income (Expense) Income (loss) before income tax expense (benefit) Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income tax expense (benefit) Net income (loss) per share: Weighted average shares outstanding: Basic (in shares) Diluted (in shares) Condensed Statements of Cash Flows Net cash provided by operating activities Capital contributions to subsidiaries Payments to Acquire Additional Interest in Subsidiaries Dividends received from subsidiaries Proceeds from Dividends Received Proceeds from sales and maturities of investments Change in amounts due to/from affiliates Changes In Amounts Due To And Due From Affiliates Changes in amounts due to and due from affiliates. Repayment of principal amount of convertible notes Proceeds from borrowings under credit facility Proceeds From Borrowings Under Credit Facility Proceeds From Borrowings Under Credit Facility Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Other Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Gross goodwill Goodwill, Gross Accumulated impairment loss Goodwill, Impaired, Accumulated Impairment Loss Goodwill impairment charges Goodwill, Impairment Loss Future Amortization Expenses Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Future amortization expense, 2020 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Future amortization expense, 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Two Future amortization expense, 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Three Future amortization expense, 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Four Future amortization expense, 2024 Finite-Lived Intangible Assets, Amortization Expense, Year Five Impairment of intangible assets Impairment of Intangible Assets, Finite-lived Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Government receivables Government Receivables [Member] Government Receivables [Member] Structured Securities Structured Securities [Member] Structured Securities [Member] Medicaid Expansion Medicaid Expansion [Member] Medicaid Expansion [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Retained Earnings, Including Deferred Income Tax Retained Earnings, Including Deferred Income Tax [Member] Retained Earnings, Including Deferred Income Tax [Member] Deferred Income Tax Deferred Income Tax [Member] Deferred Income Tax [Member] California, Illinois, New Mexico, Ohio, South Carolina, Texas, Washington, and Wisconsin California, Illinois, New Mexico, Ohio, South Carolina, Texas, Washington, and Wisconsin [Member] California, Illinois, New Mexico, Ohio, South Carolina, Texas, Washington, and Wisconsin [Member] Final maturities of investments Investments, Maturity Period Investments, Maturity Period Average maturity of investments Investments, Average Maturity Period Investments, Average Maturity Period Useful life Finite-Lived Intangible Asset, Useful Life Medical premium liability based on medical costs threshold Medical Premiums Liability, Medical Care Costs Threshold Medical Premiums Liability, Medical Care Costs Threshold Risk adjustment payable Affordable Care Act, Premium Stabilization Program, Risk Adjustment, (Payable) Affordable Care Act, Premium Stabilization Program, Risk Adjustment, (Payable) Risk adjustment receivable Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable Risk adjustment, net payable Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Net Payable Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Net Payable Percentage of additional incremental revenue earned Percentage Of Additional Incremental Revenue Earned Percentage of additional incremental revenue earned. Prepaid reinsurance premiums Prepaid Reinsurance Premiums Reinsurance recoveries Insurance Recoveries Reinsurance recoverable for unpaid claims adjustments Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Adoption of new accounting standard Concentration risk, percentage Concentration Risk, Percentage Receivables from state and federal government agencies Condensed Financial Information of Registrant Condensed Financial Information of Parent Company Only Disclosure [Text Block] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Beginning balance Goodwill Acquisitions Goodwill, Acquired During Period Dispositions Goodwill, Written off Related to Sale of Business Unit Impairment and other Ending balance Unrealized investment income (loss) Less: effect of income taxes Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Maturities of long-term debt Schedule of Maturities of Long-term Debt [Table Text Block] Long term debt Schedule of Long-term Debt Instruments [Table Text Block] Interest costs Schedule Of Debt Instruments Interest Cost Recognized [Table Text Block] Schedule of debt instruments interest cost recognized. Fair value of assets measured on recurring basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Fair value measurements of senior notes Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Benefit Year 2019 Claims paid Segments Segment Reporting Disclosure [Text Block] Gross realized investment gains Debt Securities, Available-for-sale, Realized Gain Employee Benefit Plans Compensation and Employee Benefit Plans [Text Block] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Other Operating Segment Reconciling Items [Member] Total margin Add: Other operating revenues Less: Other operating expenses Less: loss on sales of subsidiaries, net of gain Less: other expenses, net Income Taxes Income Tax Disclosure [Text Block] Fair values of derivative financial instruments Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Financing Receivable, Past Due [Table] Pharmacy rebate receivables Pharmacy Rebate Receivables [Member] Pharmacy Rebate Receivables [Member] Health insurer fee reimbursement receivables Health Insurer Fee Reimbursement Receivables [Member] Health Insurer Fee Reimbursement Receivables [Member] Other Other Receivables [Member] Other Receivables [Member] Financing Receivable, Past Due [Line Items] Total receivables Property, Equipment, and Capitalized Software, Net Property, Plant and Equipment Disclosure [Text Block] Significant Accounting Policies Significant Accounting Policies [Text Block] Derivative [Table] Derivative [Table] 1.125% Call Option Current assets Current Assets [Member] Current Assets [Member] Current liabilities Current Liabilities [Member] Current Liabilities [Member] Derivative [Line Items] Derivative [Line Items] Derivative asset Derivative Asset, Fair Value, Gross Asset Derivative liability Derivative Liability, Fair Value, Gross Liability Percentage of contractual interest rate on derivative Convertible debt, converted amount of instrument Debt Conversion, Converted Instrument, Amount Condensed balance sheets Condensed Balance Sheet [Table Text Block] Condensed statements of income Condensed Income Statement [Table Text Block] Condensed statements of comprehensive (loss) Comprehensive Income (Loss) [Table Text Block] Condensed statements of cash flows Condensed Cash Flow Statement [Table Text Block] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Services revenue from subsidiaries Revenue from Related Parties 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] Contract rights and licenses Contract Rights and Licensing Agreements [Member] Contract Rights and Licensing Agreements [Member] Provider networks Provider Networks [Member] Provider networks. Cost Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Carrying Amount Finite-Lived Intangible Assets, Net