Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Current liabilities: Derivative liability Current Liabilities [Member] Current Liabilities [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] 1.125% Conversion Option Embedded Derivative Financial Instruments [Member] Measurement Basis [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] 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] Convertible Notes Convertible Debt [Member] Credit Facility Revolving Credit Facility [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] 1.125% Notes Cash Convertible Senior Notes due 2020 [Member] Cash Convertible Senior Notes due 2020 [Member] 4.875% Notes 4.875% Senior Notes [Member] 4.875% Senior Notes [Member] 1.625% Notes (2) Convertible Senior Notes Due 2044 [Member] Convertible Senior Notes Due 2044 [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Percentage of contractual interest rate on Notes Debt Instrument, Interest Rate, Stated Percentage Fair value of debt Debt Instrument, Fair Value Disclosure Derivative liabilities Derivative Liability, Fair Value, Gross Liability Statement of Financial Position [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Investments Marketable Securities, Current Restricted investments Restricted Investments, Current Receivables Receivables, Net, 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 Goodwill and intangible assets, net Intangible Assets, Net (Including Goodwill) Restricted investments Restricted Investments, Noncurrent Deferred income taxes Deferred Income Tax Assets, Net Other assets Other Assets, Noncurrent Total assets Assets Current liabilities: Liabilities, Current [Abstract] Medical claims and benefits payable Liability for Claims and Claims Adjustment Expense Amounts due government agencies Medical Premium Liability Due To Agency Medical Premium Liability Due to Agency Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Deferred revenue Contract with Customer, Liability, Current Current portion of long-term debt Long-term Debt and Capital Lease Obligations, Current Derivative liability Derivative Liability, Current Total current liabilities Liabilities, Current Long-term debt Long-term Debt, Excluding Current Maturities Lease financing obligations 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 shares authorized; outstanding: 62 shares at September 30, 2018 and 60 shares at December 31, 2017 Common Stock, Value, Outstanding Preferred stock, $0.001 par value; 20 shares authorized, no shares issued and outstanding Preferred Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive 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 Fair value of assets measured on recurring basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Schedule of fair value, asset and liabilities measured on recurring basis - disclosure only Schedule Of Fair Value, Asset And Liabilities Measured On Recurring Basis [Table Text Block] Schedule of Fair Value, Asset and Liabilities Measured on Recurring Basis [Table Text Block] Stockholders' Equity Note [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Restructuring and separation costs Restructuring Charges [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] Cash Convertible Senior Notes Due 2020, Warrants Cash Convertible Senior Notes Due 2020, Warrants [Member] Cash Convertible Senior Notes Due 2020, Warrants [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Stock Common Stock [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted Stock Awards Restricted Stock [Member] Performance Stock Awards Performance Shares [Member] Performance Stock Units Restricted Stock Units (RSUs) [Member] Employee Stock Option Employee Stock Option [Member] Class of Stock [Line Items] Class of Stock [Line Items] Debt conversion (in shares) Debt Conversion, Converted Instrument, Shares Issued Number of warrants issued (in shares) Debt Conversion, Converted Instrument, Warrants or Options Issued Warrant, strike price per share (in dollars per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Stated percentage of warrants Class Of Warrant Or Right, Stated Interest Rate Class Of Warrant Or Right, Stated Interest Rate Warrants outstanding (in shares) Class of Warrant or Right, Outstanding Cash paid for partial termination of 1.125% Warrants Payments for Repurchase of 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 common stock issued (in shares) Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Share-based compensation Share-based Compensation Unrecognized compensation expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted average period for recognition Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Unrecognized compensation forfeiture rate Unrecognized Compensation Forfeited Rate Unrecognized compensation forfeited rate. Stock options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Stock options exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments Schedule of Long-term Debt Instruments [Table] Convertible Notes Credit Facility Debt Instrument [Line Items] Debt Instrument [Line Items] Current portion of long-term debt: Debt, Current [Abstract] Debt net of unamortized discount 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 Current portion of long-term debt Non-current portion of long-term debt: Long-term Debt, Excluding Current Maturities [Abstract] Debt net of unamortized debt discount 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 Senior notes Total debt Long-term Debt and Capital Lease Obligations, Including Current Maturities Unamortized discount Debt Instrument, Unamortized Discount Accounting Policies [Abstract] Restricted Cash and Cash Equivalents Restrictions on Cash and Cash Equivalents [Table Text Block] Schedule of Cash and Cash Equivalents Schedule of Cash and Cash Equivalents [Table Text Block] Quality incentive premium revenue recognized Quality Incentive Premium Revenue Recognized [Table Text Block] Quality incentive premium revenue recognized. Condensed Financial Information [Abstract] Condensed Financial Information [Abstract] Supplemental Condensed Consolidating Financial Information Condensed Financial Statements [Text Block] 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] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast Scenario, Forecast [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Restructuring and separation costs Restructuring Costs Expected restructuring costs Restructuring and Related Cost, Expected Cost Remaining Significant Accounting Policies Significant Accounting Policies [Text Block] Investments, Debt and Equity Securities [Abstract] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Fair Value Measurements, Recurring and Nonrecurring Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Quoted Market Prices (Level 1) Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] 1.125% Call Option Call Option, Derivative Asset [Member] Call Option, Derivative Asset [Member] 1.125% Conversion Option derivative liability Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Corporate debt securities Corporate Debt Securities [Member] U.S. treasury notes US Treasury Notes Securities [Member] Government-sponsored enterprise securities (GSEs) US Government-sponsored Enterprises Debt Securities [Member] Municipal securities Municipal Securities [Member] Municipal securities. Asset-backed securities Asset-backed Securities [Member] Certificate of deposit Certificates of Deposit [Member] Other Other Financial Instruments [Member] Other Financial Instruments [Member] Subtotal - current investments Current Investments [Member] Current Investments [Member] 1.125% Call Option derivative asset Derivative Financial Instruments, Assets [Member] Restricted Cash and Cash Equivalents [Axis] Restricted Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] U.S. treasury notes US Treasury Securities [Member] Subtotal - current restricted investments Restricted Investments, Current [Member] Restricted Investments, Current [Member] 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] Total assets measured at fair value on a recurring basis Assets, Fair Value Disclosure 1.125% Conversion Option derivative liability Derivative Liability Total liability measured at fair value on a recurring basis Financial and Nonfinancial Liabilities, Fair Value Disclosure Percentage of contractual interest rate on Call Option Derivative, Fixed Interest Rate Statement of Cash Flows [Abstract] Statement Statement [Table] 1.125% Notes 1.125% Notes [Member] 1.125% Notes [Member] 1.625% Notes 1.625% Notes [Member] 1.625% Notes [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 (used in) provided by 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 Non-cash restructuring costs Non-cash Restructuring Charges Non-cash Restructuring Charges Amortization of convertible senior notes and lease financing obligations Amortization Of Debt Discount (Premium) And Sale Leaseback Financing Obligation Amortization of Debt Discount (Premium) and Sale Leaseback Financing Obligation Gain on sale of subsidiary Gain (Loss) on Disposition of Business Loss on debt extinguishment Gain (Loss) on Extinguishment of Debt 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 (used in) provided by 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 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 credit facility Repayments of Lines of Credit Repayment of principal amount of Notes Payments to Acquire Notes Receivable Cash paid for partial settlement of 1.125% Conversion Option Cash Paid For Settlement Of Conversion Option Cash Paid For Settlement Of Conversion Option Cash received for partial termination of 1.125% Call Option Proceeds from Convertible Debt Cash paid for partial termination of 1.125% Warrants Proceeds from senior notes offerings, net of issuance costs Proceeds from Issuance of Debt Proceeds from borrowings under credit facility Proceeds from Long-term 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 increase in cash, 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, cash equivalents, and restricted cash and cash equivalents at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents, and restricted cash and cash equivalents at end of period Supplemental cash flow information: Supplemental Cash Flow Information [Abstract] Schedule of non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Common stock used for share-based compensation Stock Issued 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 1.625% Notes exchange transaction: Business Combination, Description [Abstract] Common stock issued in exchange for 1.625% Notes Notes Issued Component of 1.625% 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 Details of sale of subsidiary: 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 Receivable from buyer - recorded in prepaid expenses and other current assets Disposition of Business, Receivable from Buyer Disposition of Business, Receivable from Buyer Gain on sale of subsidiary Statement of Stockholders' Equity [Abstract] 1.625% Notes Percentage of contractual interest rate Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Health Plans Health Plans [Member] Health plans. Molina Medicaid Solutions Medicaid Solutions Segment [Member] Molina Medicaid solutions segment. Other Other Segments [Member] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Separation Costs - Former Executives Employee Severance [Member] One-Time Termination Benefits One-time Termination Benefits [Member] Write-offs of Long-lived Assets Capitalized Software Write-Off [Member] Capitalized Software Write-Off [Member] Consulting Fees Professional Services Fees [Member] Professional Services Fees [Member] Contract Termination Costs Contract Termination [Member] Restructuring and separation costs Schedule of Available-for-sale Securities Schedule of Available-for-sale Securities [Table] U.S. treasury notes GSEs Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Amortized Cost Debt Securities, Available-for-sale, Amortized Cost Gross Unrealized Gains Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Losses Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Estimated Fair Value Available-for-sale Securities Percentage of contractual interest rate on derivative Earnings Per Share [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] 1.125% Warrants 1.125% Warrants [Member] 1.125% Warrants [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Numerator: Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Denominator: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Shares outstanding at the beginning of the period (in shares) Shares, Outstanding Exchange of 1.625% Notes (in shares) Weighted Average Number of Shares Issued, Basic 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 per share (in shares) Weighted Average Number of Shares Outstanding, Basic Effect of dilutive securities: Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] 1.125% Warrants (in shares) Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants 1.625% Notes (in shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Stock-based compensation (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Denominator for diluted net 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) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Potentially dilutive common shares excluded from calculations: Potentially Dilutive Common Shares Excluded From Calculations [Abstract] Potentially Dilutive Common Shares Excluded From Calculations [Abstract] 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 Earnings Per Share, Share Based Compensation, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Share Based Compensation, Amount Restricted share activity Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] Schedule Of Premium Revenue By Health Plan Type Schedule of Premium Revenue by Health Plan Type [Table] Schedule of premium revenue by health plan type. Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Select Health Plans California, Illinois, New Mexico, Ohio, South Carolina, Texas, Washington, and Wisconsin [Member] California, Illinois, New Mexico, Ohio, South Carolina, Texas, Washington, and Wisconsin [Member] Schedule of Premium Revenue by Health Plan Type [Line Items] Schedule of Premium Revenue by Health Plan Type [Line Items] Schedule of premium revenue by health plan type. Percentage of additional incremental revenue earned Percentage Of Additional Incremental Revenue Earned Percentage of additional incremental revenue earned. Maximum available quality incentive premium - current period Maximum Available Quality Incentive Premium Current Year Maximum available quality incentive premium current year. Quality incentive premium revenue recognized in current period: Quality Incentive Premium Revenue Recognized [Abstract] Quality Incentive Premium Revenue Recognized [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 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 Derivative Instruments and Hedging Activities Disclosure [Abstract] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Statement of Comprehensive Income [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Unrealized investment gain (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 Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Net Income (Loss) per Share Earnings Per Share [Text Block] Restricted cash and cash equivalents Restricted Cash and Cash Equivalents Total cash, cash equivalents, and restricted cash and cash equivalents presented in the statements of cash flows Summary of denominators for the computation of basic and diluted net income (loss) per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Parent Guarantor Parent Company [Member] Other Guarantors Guarantor Subsidiaries [Member] Non-Guarantors Non-Guarantor Subsidiaries [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Reportable Legal Entities Reportable Legal Entities [Member] Eliminations Consolidation, Eliminations [Member] Condensed Statement of Income Captions [Line Items] Condensed Statement of Income Captions [Line Items] Other comprehensive income, net of tax Condensed Income Statement [Table] Condensed Income Statement [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Health Care, Premium Health Care, Premium [Member] Technology Service Technology Service [Member] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Revenue: Revenues [Abstract] Total revenue Revenues Expenses: Costs and Expenses [Abstract] Cost of revenue Cost of Goods and Services Sold General and administrative expenses General and Administrative Expense 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 Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Restructuring and separation costs Total operating expenses Costs and Expenses Gain on sale of subsidiary Operating income (loss) Operating Income (Loss) Interest expense Interest Expense Other expenses (income), net Other 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) Income Tax Expense (Benefit) Net loss before equity in net (losses) earnings 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 of subsidiaries Income (Loss) from Subsidiaries, Net of Tax Net income (loss) In a Continuous Loss Position for Less than 12 Months, Estimated Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value In a Continuous Loss Position for Less than 12 Months, Unrealized Losses Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss In a Continuous Loss Position for Less than 12 Months, Number of Positions (in security) Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year In a Continuous Loss Position for 12 Months or More, Estimated Fair value Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value In a Continuous Loss Position for 12 Months or More, Unrealized Losses Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss In a Continuous Loss Position for 12 Months or More, Number of Positions (in security) Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year Condensed Financial Statements [Table] Condensed Financial Statements [Table] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Aggregate principal amount of notes outstanding Long-term Debt, Gross Presentation and Reclassification Reclassification, Policy [Policy Text Block] Consolidation And Interim Financial Information Consolidation And Interim Financial Information, Policy [Policy Text Block] Consolidation And Interim Financial Information, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table] Operating Segments Operating Segments [Member] Other operating Segment Reconciling Items [Member] Other Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Gross margin Gross Profit Add: other operating revenues Add: gain on sale of subsidiary Total operating expenses Other expenses, net Nonoperating Income (Expense) Schedule of Deferred Compensation Arrangement with Individual, Share-based Payments [Table] Schedule of Deferred Compensation Arrangement with Individual, Share-based Payments [Table] Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Beginning Balance (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited (shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Ending Balance (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] Begining 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 Ending Balance (usd per share) Other Liabilities Disclosure [Abstract] Insurance Claims Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Medical claims and benefits payable, beginning balance Components of medical care costs related to: Components Of Medical Care Costs [Abstract] Components of medical care costs. 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 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: Payments For Medical Care Costs [Abstract] Payments for medical care costs. 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 Entities [Table] Entities [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] California Department of Health Care Services California Department of Health Care Services [Member] California Department of Health Care Services [Member] Entity Information [Line Items] Entity Information [Line Items] Premium revenue Premiums Earned, Net Net assets of subsidiaries subject to restrictions Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries 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 2019 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2020 Long-term Debt, Maturities, Repayments of Principal in Year Two 2021 Long-term Debt, Maturities, Repayments of Principal in Year Three 2022 Long-term Debt, Maturities, Repayments of Principal in Year Four 2023 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Long-term Debt, Gross Common stock, par value (usd per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Preferred stock, par value (usd per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Derivative Derivative [Table] Current assets: Derivative asset Current Assets [Member] Current Assets [Member] Derivative [Line Items] Derivative [Line Items] Derivative assets Derivative Asset, Fair Value, Gross Asset Debt conversion, net cash receipts Debt Conversion, Converted Instrument, Amount Medical Claims and Benefits Payable Medical Claims And Benefits Payable [Text Block] Medical claims and benefits payable. Contractual interest at coupon rate Interest Expense, Debt, Excluding Amortization Amortization of the discount Amortization of Debt Discount (Premium) Interest expense, debt Interest Expense, Debt Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] CMS Subsidies CMS Subsidies [Member] CMS Subsidies [Member] Medical Premium Liability Due to Agency Medical Premium Liability Due to Agency [Member] Medical Premium Liability Due to Agency [Member] Medicaid Expansion Medicaid Expansion [Member] Medicaid Expansion [Member] Medical premiums liability based on medical cost thresholds Medical Premiums Liability, Medical Care Costs Threshold Medical Premiums Liability, Medical Care Costs Threshold Risk adjustment receivable (payable) Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable (Payable) Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable (Payable) Operating expense Disposal Group, Including Discontinued Operation, Operating Expense Additional medical care costs incurred Additional Medical Care Costs Incurred Additional Medical Care Costs Incurred Maturity period Investments, Maturity Period Investments, Maturity Period Average maturity period Investments, Average Maturity Period Investments, Average Maturity Period Adjustments to provisional valuation of deferred tax assets and liabilities Tax Cuts And Jobs Act Of 2017, Change In Tax Rate, Deferred Tax Asset, Income Tax Expense (Benefit) Tax Cuts And Jobs Act Of 2017, Change In Tax Rate, Deferred Tax Asset, Income Tax Expense (Benefit) 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] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Total fair value of awards 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 Total fair value of awards vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Investments Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Contractual maturities of investments Investments Classified by Contractual Maturity Date [Table Text Block] Schedule of available for sale securities continuous unrealized loss position Schedule Of Available For Sale Securities Continuous Unrealized Loss Position [Table Text Block] Schedule of available for sale securities continuous unrealized loss position. Schedule of 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. Condensed Consolidating Statements of Income Condensed Income Statement [Table Text Block] Condensed Consolidating Statements of Comprehensive Income Condensed Statement of Comprehensive Income [Table Text Block] Condensed Consolidating Balance Sheets Condensed Balance Sheet [Table Text Block] Condensed Consolidating Statements of Cash Flows Condensed Cash Flow Statement [Table Text Block] Segments Segment Reporting Disclosure [Text Block] Restructuring and Separation Costs Restructuring and Related Activities Disclosure [Text Block] Non-risk provider payables Medical Claims And Benefits Payable Medical Claims and Benefits Payable Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Line Items] Liability for Claims and Claims Adjustment Expense [Line Items] Percentage of IBNP not expected to be paid Short-Duration Insurance Contracts, Liability For Unpaid Claims And Claims Adjustment Expense, Uncollectible Claims Assumption Short-Duration Insurance Contracts, Liability For Unpaid Claims And Claims Adjustment Expense, Uncollectible Claims Assumption Expense (recovery) for prior period claims development Document and Entity Information [Abstract] -- None. No documentation exists for this element. -- Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Trading Symbol Trading Symbol Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding 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 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] Debt Long-term Debt [Text Block] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] ASSETS Assets [Abstract] Due from (to) affiliates Related Party Transaction, Due from (to) Related Party, Current Investment in subsidiaries, net Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Long-term debt and lease financing obligations Long-term Debt and Capital Lease Obligations Deferred income taxes Deferred Income Tax Liabilities, Net Total stockholders’ equity Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Additional Paid-in Capital Additional Paid-in Capital [Member] Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Retained Earnings Retained Earnings [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Topic 606 Accounting Standards Update 2014-09 [Member] ASU 2018-02 Accounting Standards Update 2018-02 [Member] Accounting Standards Update 2018-02 [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance (in shares) Beginning Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Adoption of ASU Cumulative Effect of New Accounting Principle in Period of Adoption Partial termination of 1.125% Warrants Adjustments to Additional Paid in Capital, Other Exchange of 1.625% Notes (in shares) Conversion of 1.625% Notes Other comprehensive income, net Share-based compensation Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Ending Balance (in shares) Ending Balance Amortized Cost Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [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 Estimated Fair Value Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [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 Estimated Fair Value Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value Line of Credit Line of Credit [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Letter of Credit Letter of Credit [Member] Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Term of debt instrument Debt Instrument, Term Amount outstanding under Letter of Credit Long-term Line of Credit Current borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Face amount Debt Instrument, Face Amount Repayments of principal Debt Instrument, Periodic Payment, Principal Repayments of debt Repayments of Debt Cash paid for partial settlement of conversion option Debt conversion Conversion ratio Debt Instrument, Convertible, Conversion Ratio Conversion price per share of common stock (in dollars per share) Debt Instrument, Convertible, Conversion Price Effective interest percentage Debt Instrument, Interest Rate, Effective Percentage Remaining amortization period Debt Instrument, Convertible, Remaining Discount Amortization Period If-converted value Debt Instrument, Convertible, If-converted Value in Excess of Principal Loss on debt extinguishment Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] Fee-for-service claims incurred but not paid (IBNP) Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) 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 Medical claims and benefits payable Schedule of Business Acquisitions by Acquisition, Equity Interest Issued or Issuable [Table] Schedule of Business Acquisitions by Acquisition, Equity Interest Issued or Issuable [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Business Acquisition, Equity Interests Issued or Issuable [Line Items] Business Acquisition, Equity Interests Issued or Issuable [Line Items] Number of reportable segments (in segment) Number of Reportable Segments Net cash selling price of equity interests Net Cash Selling Price Of Equity Interests Net Cash Selling Price Of Equity Interests Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis Of Presentation [Table] Basis Of Presentation [Table] Basis Of Presentation [Table] Pathways Pathways Health And Community Support LLC [Member] Pathways Health And Community Support LLC [Member] New Mexico NEW MEXICO Puerto Rico PUERTO RICO Florida FLORIDA Washington WASHINGTON Basis Of Presentation [Line Items] Basis Of Presentation [Line Items] Basis Of Presentation [Line Items] Number of states in which entity operates (in state) Number of States in which Entity Operates Number of members eligible for the health care programs, approximately (in member) 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 terms Maximum Contract Term Maximum contract term. Number of members served, approximately (in member) Health Care Organization, Number Of Members Health Care Organization, Number of Members Revenue Revenue from Contract with Customer, Including Assessed Tax Expected number of members served, approximately (in member) Health Care Organization, Expected Number Of Members Health Care Organization, Expected Number Of Members Income Statement [Abstract] Revenue from External Customers by Products and Services [Table] Revenue from External Customers by Products and Services [Table] Revenue from External Customer [Line Items] Revenue from External Customer [Line Items] Service revenue Insurance Services 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 Investment income and other revenue Interest and Dividend Income, Operating Total revenue Operating expenses: Impairment losses Other expenses, net: Nonoperating Income (Expense) [Abstract] Total other expenses, net Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Net cash provided by operating activities Capital contributions to subsidiaries Capital Contributions To Subsidiaries Capital Contributions To Subsidiaries Dividends from subsidiaries Dividends From Subsidiaries Dividends From Subsidiaries 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. Proceeds from senior notes offerings, net of issuance costs Proceeds from Debt, Net of Issuance Costs Proceeds from borrowings under credit facility Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Separation Costs - Former Executives One-Time Termination Benefits Other Restructuring Costs Other Restructuring [Member] Restructuring Reserve Restructuring Reserve [Roll Forward] Accrued as of December 31, 2017 Restructuring Reserve Adjustments Restructuring Reserve, Accrual Adjustment Charges Restructuring Charges Cash payments Payments for Restructuring Accrued as of September 30, 2018 Amortized Cost Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract] Due in one year or less Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due after one year through five years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Debt Securities, Held-to-maturity Debt Securities, Held-to-maturity Estimated Fair Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Due in one year or less Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due after one year through five years Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Estimated Fair Value, Total Debt Securities, Held-to-maturity, Fair Value Operating segment information Schedule of Segment Reporting Information, by Segment [Table Text Block] Restructuring Costs Restructuring and Related Costs [Table Text Block] Restructuring Reserve Schedule of Restructuring Reserve by Type of Cost [Table Text Block]