Statement of Comprehensive Income [Abstract] Net (loss) income Net Income (Loss) Attributable to Parent Other comprehensive (loss) income: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Unrealized investment (loss) gain Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Less: effect of income taxes Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Other comprehensive (loss) income, net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive (loss) income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Accounting Policies [Abstract] 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, Including Intangible Assets Property, Plant and Equipment, Policy [Policy Text Block] Deferred Contract Costs Deferred Contract Costs [Policy Text Block] Deferred Contract Costs [Policy Text Block] Business Combinations Business Combinations Policy [Policy Text Block] Premium Revenue - Health Plans Premium Revenue [Policy Text Block] Premium revenue. Medical Care Costs - Health Plans Health Care Costs, Policy [Policy Text Block] Taxes Based on Premiums Taxes Based On Premiums [Policy Text Block] Taxes based on premiums. Premium Deficiency Reserves on Loss Contracts Premium Deficiency Reserves On Loss Contracts [Policy Text Block] Premium Deficiency Reserves on Loss Contracts [Policy Text Block] 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 Not Yet Adopted and Recent Accounting Pronouncements Adopted New Accounting Pronouncements, Policy [Policy Text Block] Receivables Receivables, Policy [Policy Text Block] Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Insurance [Abstract] Incurred claims and allocated claims adjustment expenses Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net Less: cumulative paid clams and allocated claims adjustment expenses Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net Non-risk provider payables and other Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Aggregate Reconciling Items Medical claims and benefits payable Liability for Claims and Claims Adjustment Expense Investments, Debt and Equity Securities [Abstract] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Corporate debt securities Corporate Debt Securities [Member] U.S. treasury notes US Treasury Notes Securities [Member] GSEs US Government-sponsored Enterprises Debt Securities [Member] Municipal securities Municipal Securities [Member] Municipal securities. Asset-backed securities Asset-backed Securities [Member] Certificates of deposit Certificates of Deposit [Member] Subtotal - current investments Current Investments [Member] Current Investments [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] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Investments Schedule Of Available For Sale Securities Reconciliation [Abstract] Schedule of available for sale securities reconciliation. Amortized Cost Available-for-sale Debt Securities, Amortized Cost Basis 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 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] Equity Award [Domain] Restricted Stock Awards Restricted Stock [Member] Performance Stock Awards Performance Shares [Member] Performance Stock Units Restricted Stock Units (RSUs) [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [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 Commitments and Contingencies Disclosure [Abstract] Summary of future minimum lease payments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 1.125% Convertible Notes Cash Convertible Senior Notes due 2020 [Member] Cash Convertible Senior Notes due 2020 [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Convertible Debt Convertible Debt [Member] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2011 Plan Two Thousand And Eleven Plan [Member] Two thousand and eleven plan. Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Stock Common Stock [Member] Stock options Employee Stock Option [Member] Employee Stock Purchase Plan Employee Stock [Member] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Separation Costs - Former Executives Employee Severance [Member] Threshold percentage of stock price trigger Class of Warrant or Right, Threshold Percentage of Stock Price Trigger Class of Warrant or Right, Threshold Percentage of Stock Price Trigger Convertible debt, shares converted in transaction (in shares) Debt Conversion, Converted Instrument, Shares Issued 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 Trading days measurement period (in days) Class of Warrant or Right, Trading Days Measurement Period Class of Warrant or Right, Trading Days Measurement Period Stated interest rate for Warrants Class Of Warrant Or Right, Stated Percentage Class of Warrant or Right, Stated Percentage Number of shares authorized (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Share-based compensation (in shares) Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Maximum award vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Stock option expiration period Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Unrecognized compensation expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted average period of unrecognized compensation expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Unrecognized compensation forfeited rate Unrecognized Compensation Forfeited Rate Unrecognized compensation forfeited rate. Accelerating vesting awards (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number Restructuring settled without cash Restructuring Reserve, Settled without Cash 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 Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Disclosures [Text Block] 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 2015 Short-duration Insurance Contracts, Accident Year 2015 [Member] Benefit Year 2016 Short-duration Insurance Contracts, Accident Year 2016 [Member] Benefit Year 2017 Short-duration Insurance Contracts, Accident Year 2017 [Member] Product Information [Line Items] Product Information [Line Items] Claims paid Restructuring and Related Activities [Abstract] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] Deferred termination fee Deferred Termination Fee [Member] Deferred Termination Fee [Member] Deferred bonus Deferred Bonus [Member] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Executive Officers Executive Officer [Member] Chief Executive Officer Chief Executive Officer [Member] Chief Financial Officer Chief Financial Officer [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Cash awards as a percentage of base salary Deferred Compensation Arrangement with Individual, Cash Awards Granted, Percentage Restructuring and separation costs Restructuring Costs Charges Restructuring Charges Acceleration of share-based compensation Debt Disclosure [Abstract] Schedule Of Maturities Of Long Term Debt [Table] Schedule Of Maturities Of Long Term Debt [Table] Schedule of maturities of long term debt. Senior Notes Senior Notes [Member] Credit Facility Line of Credit [Member] 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] 1.625% Convertible Notes Convertible Senior Notes Due 2044 [Member] Convertible Senior Notes Due 2044 [Member] Maturities Of Long Term Debt [Line Items] Maturities Of Long Term Debt [Line Items] Maturities of long-term debt. Maturities of Long-term Debt [Abstract] Maturities of Long-term Debt [Abstract] Net carrying amount Long-term Debt, Gross 2018 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2019 Long-term Debt, Maturities, Repayments of Principal in Year Two 2020 Long-term Debt, Maturities, Repayments of Principal in Year Three 2021 Long-term Debt, Maturities, Repayments of Principal in Year Four 2022 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Percentage of contractual interest rate Debt Instrument, Interest Rate, Stated Percentage Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Line Items] Debt Instrument [Line Items] 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 Current portion of long-term debt Long-term Debt and Capital Lease Obligations, Current 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 Long-term debt Long-term Debt, Excluding Current Maturities Lease financing obligations Capital Lease Obligations, Noncurrent Principal Balance Long-term Debt and Capital Lease Obligations, Including Current Maturities Long-term Debt and Capital Lease Obligations, Including Current Maturities Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] 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] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance, shares Shares, Outstanding Beginning Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Other comprehensive income (loss), net Common stock offering, including issuance costs, shares Stock Issued During Period, Shares, New Issues Common stock offering, including issuance costs Stock Issued During Period, Value, New Issues Issuance of common stock in connection with 1.625% Notes exchange, shares Stock Issued During Period, Shares, Conversion of Convertible Securities 1.625% Convertible Notes exchange transaction Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature Share-based compensation, shares Share-based compensation Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Tax benefit from share-based compensation Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Ending Balance, shares Ending Balance Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis Of Presentation [Table] Basis Of Presentation [Table] Basis Of Presentation [Table] Health Plan Name [Axis] Health Plan Name [Axis] Health Plan Name Health Plan Name [Domain] Health Plan Name [Domain] [Domain] for Health Plan Name Medicaid Medicaid [Member] Medicaid [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Florida FLORIDA Miami Dade and Monroe Counties Miami Dade And Monroe Counties, Florida [Member] Miami Dade And Monroe Counties, Florida [Member] New Mexico NEW MEXICO Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Molina Healthcare of Illinois, Inc. Molina Healthcare of Illinois, Inc. [Member] Molina Healthcare of Illinois, Inc. [Member] Mississippi Coordinated Access Network Mississippi Coordinated Access Network [Member] Mississippi Coordinated Access Network [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Health Plans Health Plans [Member] Health plans. Gain Contingencies, Nature [Axis] Gain Contingencies, Nature [Axis] Gain Contingency, Nature [Domain] Gain Contingency, Nature [Domain] Medicare Acquisition terminated Acquisition Contract Termination [Member] Acquisition Contract Termination [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Restatement Adjustment Restatement Adjustment [Member] Basis Of Presentation [Line Items] Basis Of Presentation [Line Items] Basis Of Presentation [Line Items] Number of reportable segments (in segment) 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 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 Premium revenue Health Care Organization, Premium Revenue Services contract term Services Contract Term Services Contract Term Services contract renewal term Services Contract Renewal Term Services Contract Renewal Term Termination fee receivable under asset purchase agreement Gain Contingency, Unrecorded Amount Health insurer fees reimbursed Health Care Organization, Insurer Fee Revenue Health Care Organization, Insurer Fee Revenue Condensed Financial Information of Parent Company Only Disclosure [Abstract] Schedule of 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 Statements of Cash Flows Statement of Cash Flows [Abstract] Operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Capital contributions to subsidiaries Payments to Acquire Additional Interest in Subsidiaries Dividends received from subsidiaries Proceeds from Dividends Received 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 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. Other, net Payments for (Proceeds from) Other Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] 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 Proceeds from common stock offering, net of issuance costs Proceeds from Issuance of Common Stock Proceeds from employee stock plans Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options Cash paid for financing transaction fees Payments of Financing Costs Other, net Proceeds from (Payments for) Other Financing Activities Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Net increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Income Statement [Abstract] Revenue: Revenues [Abstract] Service revenue Technology Services Revenue Premium tax revenue Health Care Organization, Premium Tax Revenue Health Care Organization, Premium Tax Revenue Investment income and other revenue Interest and Dividend Income, Operating Total revenue Revenues Operating expenses: Costs and Expenses [Abstract] Medical care costs Policyholder Benefits and Claims Incurred, Net, Health Cost of service revenue Technology Services Costs 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 Impairment losses Goodwill and Intangible Asset Impairment Total operating expenses Costs and Expenses Operating (loss) income Operating Income (Loss) Interest expense Interest Expense Other income, net Other Nonoperating Income (Expense) Total other expenses, net Nonoperating Income (Expense) (Loss) income before income tax (benefit) expense Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income tax (benefit) expense Income Tax Expense (Benefit) Net (loss) income Net (loss) income per share: Earnings Per Share [Abstract] Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Weighted average shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted One-Time Termination Benefits One-time Termination Benefits [Member] Other Restructuring Costs Other Restructuring [Member] Restructuring Reserve Restructuring Reserve [Roll Forward] Accrued, beginning of period Restructuring Reserve Cash payments Payments for Restructuring Accrued, end of period Insurance Claims [Table] Insurance Claims [Table] Insurance Claims [Table] Ohio OHIO California CALIFORNIA Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Medicaid Expansion Medicaid Expansion [Member] Medicaid Expansion [Member] MMP Program MMP Integrated Dual [Member] MMP Integrated Dual [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Insurance Claims [Line Items] Insurance Claims [Line Items] Insurance Claims [Line Items] Medical claims and benefits payable Medical Claims And Benefits Payable Medical Claims and Benefits Payable Reinsurance recoverable for unpaid claims Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Estimated discount percentage of final payment on claims incurred but not paid Claims Incurred But Not Paid (IBNP) Liability, Estimated Discount Percentage of Final Payment Claims Incurred But Not Paid (IBNP) Liability, Estimated Discount Percentage of Final Payment Prior period claims expense (benefit) recognized Prior Year Claims and Claims Adjustment Expense Number of members added, approximately (in member) Number Of Members Added Number of Members Added Derivative Instruments and Hedging Activities Disclosure [Abstract] Fair Values of Derivative Financial Instruments Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Restricted Investments, Non-current Restricted Assets Disclosure [Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets, Net Goodwill and Intangible Assets Disclosure [Text Block] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] 1.125% Call Option Call Option, Derivative Asset [Member] Call Option, Derivative Asset [Member] 1.125% Conversion Option Embedded Derivative Financial Instruments [Member] Fixed interest rate on derivative Derivative, Fixed Interest Rate 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] 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 Available-for-sale investments Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] 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 Number of Positions, 12 Months or Less (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 Number of Positions, 12 Months or More (in security) Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year Net (Loss) Income per Share Earnings Per Share [Text Block] Summary of restricted investments by health plan Schedule of Balances of Restricted Investments by Health Plan [Table Text Block] Schedule of balances of restricted investments by health plan. Contractual maturities of our held-to-maturity restricted investments Investments Classified by Contractual Maturity Date Held To Maturity Restricted Investments [Table Text Block] Investments classified by contractual maturities of our held-to-maturity restricted investments. Significant Accounting Policies Significant Accounting Policies [Text Block] Sale Leaseback Transaction [Table] Sale Leaseback Transaction [Table] Puerto Rico PUERTO RICO Sale Leaseback Transaction [Line Items] Sale Leaseback Transaction [Line Items] Net assets of subsidiaries subject to restrictions Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries Cash and investments Restricted Cash and Investments, Current 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 Operating lease terms Lessee, Operating Lease, Term of Contract Operating lease renewal options Operating Lease, Number of Renewal Option Operating Lease, Number of Renewal Option Rental expense related to leases Operating Leases, Rent Expense, Net Receivables [Abstract] Receivables Loans, Notes, Trade and Other Receivables Disclosure [Text Block] 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 Document Type Document Type Document Period End Date Document Period End Date 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 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 Filer Category Entity Filer Category Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Commitments and Contingencies Commitments and Contingencies 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 Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Redemption period, option one Debt Instrument, Redemption Period, Option One [Member] Debt Instrument, Redemption Period, Option One [Member] Redemption period, option two Debt Instrument, Redemption Period, Option Two [Member] Debt Instrument, Redemption Period, Option Two [Member] Net carrying amount of debt Debt instrument conversion price per share (usd per share) Debt Instrument, Convertible, Conversion Price Debt convertible threshold trading days Debt Instrument, Convertible, Threshold Trading Days Debt convertible threshold consecutive trading days Debt Instrument, Convertible, Threshold Consecutive Trading Days Debt convertible maximum threshold percentage of stock price Debt Instrument, Convertible, Maximum Threshold Percentage of Stock Price Trigger Debt Instrument, Convertible, Maximum Threshold Percentage of Stock Price Trigger Debt instrument conversion price, trigger price (usd per share) Debt Instrument, Convertible, Stock Price Trigger Debt convertible threshold percentage of stock price trigger Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger 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 Debt instrument, conversion ratio Debt Instrument, Convertible, Conversion Ratio Convertible debt, converted amount of instrument Debt Conversion, Converted Instrument, Amount Loss on debt extinguishment Gain (Loss) on Extinguishment of Debt Increase of interest rate contingent on principal amount outstanding Debt Instrument, Interest Rate Increase, Contingent on Principal Amount Outstanding Additional interest rate per year to be payable for any semiannual interest period for which principal amount outstanding on Notes is less than the required amount Minimum principal amount outstanding threshold for interest rate increase Debt Instrument, Interest Rate Increase, Minimum Principal Amount Outstanding Threshold Debt Instrument, Interest Rate Increase, Minimum Principal Amount Outstanding Threshold Debt redemption price, percentage of principal amount Debt Instrument, Redemption Price, Percentage Term of debt instrument Debt Instrument, Term Convertible debt discount amortization period Debt Instrument, Convertible, Discount Amortization Period Debt Instrument, Convertible, Discount Amortization Period Convertible debt, carrying amount of equity component Debt Instrument, Convertible, Carrying Amount of Equity Component Condensed Balance Sheets Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Investments Marketable Securities, Current Restricted investments Restricted Investments, Current Receivables Receivables, Net, Current Income taxes refundable Income Taxes Receivable, 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 Goodwill and intangible assets, net Intangible Assets, Net (Including Goodwill) 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 Assets LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Medical claims and benefits payable Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Current portion of long-term debt Derivative liability Derivative Liability, Current Total current liabilities Liabilities, Current Senior notes Convertible Notes Payable, Noncurrent Lease financing obligations Lease Financing Obligations, Noncurrent Lease Financing Obligations, Noncurrent Deferred income taxes Deferred Income Tax Liabilities, Net 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: 60 shares at December 31, 2017 and 57 shares at December 31, 2016 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 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 Schedule of Operating Leases Future Minimum Payments [Table] Schedule of Operating Leases Future Minimum Payments [Table] Schedule of Operating Leases Future Minimum Payments [Table] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Lease Financing Obligations Lease Financing Obligations [Member] Lease Financing Obligations [Member] Operating Leases Operating Leases [Member] Operating Leases [Member] Schedule of Operating Leases Future Minimum Payments [Line Items] Schedule of Operating Leases Future Minimum Payments [Line Items] [Line Items] for Schedule of Operating Leases Future Minimum Payments [Table] Summary of future minimum lease payments Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2018 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2019 Operating Leases, Future Minimum Payments, Due in Two Years 2020 Operating Leases, Future Minimum Payments, Due in Three Years 2021 Operating Leases, Future Minimum Payments, Due in Four Years 2022 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total minimum lease payments Operating Leases, Future Minimum Payments Due Income Tax Disclosure [Abstract] Significant components of deferred tax assets and liabilities Components of Deferred Tax Assets and Liabilities [Abstract] Accrued expenses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Reserve liabilities Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves 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 Unrealized losses Deferred Tax Assets, Unrealized Losses on Available-for-Sale Securities, Gross 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 Deferred compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Compensation Tax credit carryover Deferred Tax Assets, Tax Credit Carryforwards Valuation allowance Deferred Tax Assets, 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 Fixed assets and intangibles Deferred Tax Liabilities, Property, Plant and Equipment Basis in debt Deferred Tax Liabilities, Financing Arrangements Total deferred income tax liabilities Deferred Tax Liabilities, Gross Net deferred income tax asset (liability) Deferred Tax Assets, Net Net deferred income tax asset (liability) Deferred Tax Liabilities, Net Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Credit Facility Revolving Credit Facility [Member] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Fair Value Default [Member] 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] Estimated fair values of long-term debt Debt Instrument, Fair Value Disclosure 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 Gross unrecognized tax benefits at end of period Restricted stock and performance awards Restricted and Performance Stock [Member] Restricted and Performance Stock [Member] Shares 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, weighted average grant date fair value 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, weighted average grant date fair value ending balance (USD per share) Summary of property and equipment Property, Plant and Equipment [Table Text Block] Depreciation and amortization Depreciation And Amortization [Table Text Block] Depreciation and amortization. Employee stock purchase plan and stock options Employee Stock Purchase Plan and Stock Options [Member] Employee Stock Purchase Plan and Stock Options [Member] Stock based compensation expense Share-based Compensation [Abstract] Pretax Charges Allocated Share-based Compensation Expense Net-of-Tax Amount Allocated Share-based Compensation Expense, Net of Tax Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] 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 Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Illinois ILLINOIS New York NEW YORK 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] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] PCC Pathways Health And Community Support LLC [Member] Pathways Health And Community Support LLC [Member] Other Subsidiary Other Subsidiary [Member] Other Subsidiary [Member] Subsidiaries Subsidiaries [Member] Molina Medicaid Solutions Medicaid Solutions Segment [Member] Molina Medicaid solutions segment. Other Other Segments [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Goodwill impairment charges Goodwill, Impairment Loss Weighted average amortization period Finite-Lived Intangible Asset, Useful Life Impairment of intangible assets Impairment of Intangible Assets, Finite-lived Future Amortization Expenses Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] Future amortization expense, 2018 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Future amortization expense, 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Two Future amortization expense, 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Three Future amortization expense, 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Four Future amortization expense, 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Five 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 Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Revenues Gross margin Gross Profit Depreciation and amortization Depreciation, Depletion and Amortization Total assets Increase to gross profit Increase (Decrease) to Gross Profit Increase (Decrease) to Gross Profit Condensed Financial Information [Abstract] Condensed Financial Information [Abstract] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Parent Guarantor 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 Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Operating activities: Investing activities: (Increase) decrease in restricted investments held-to-maturity Increase (Decrease) of Restricted Investments Net cash paid in business combinations Payments to Acquire Businesses, Net of Cash Acquired Change in amounts due to/from affiliates Financing activities: Summary of denominators for the computation of basic and diluted earnings per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Incurred Claims and Allocated Claims Adjustment Expenses Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims 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 Cumulative number of reported claims (in claim) Short-duration Insurance Contracts, Number of Reported Claims Medical Claims and Benefits Payable Short-Duration Insurance and Deposit Contracts [Text Block] Contractual maturities of our held-to-maturity restricted investments Held-to-maturity Securities, Debt Maturities [Abstract] Amortized Cost, Due in one year or less Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount Amortized Cost, Due one year through five years Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount Amortized Cost, Total Held-to-maturity Securities Estimated Fair Value, Due in one year or less Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value Estimated Fair Value, Due one year through five years Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value Estimated Fair Value, Total Held-to-maturity Securities, Fair Value 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 Variable Interest Entities [Abstract] Variable Interest Entities [Abstract] Variable Interest Entities (VIEs) Variable Interest Entity Disclosure [Text Block] Capitalized software Software and Software Development Costs [Member] Land Land [Member] Summary of property and equipment Property, Plant and Equipment, Net, by Type [Abstract] Property and equipment, gross Property, Plant and Equipment, Gross Less: accumulated amortization - capitalized software Capitalized Computer Software, Accumulated Amortization Less: accumulated depreciation and amortization - building and improvements, furniture and equipment Property, Plant, and Equipment, Owned, Accumulated Depreciation Accumulated depreciation, Total Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, equipment, and capitalized software, net Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] 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] 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] Debt instruments interest cost recognized Schedule Of Debt Instruments Interest Cost Recognized [Table Text Block] Schedule of debt instruments interest cost recognized. Condensed Financial Information of Registrant Condensed Financial Information of Parent Company Only Disclosure [Text Block] 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 Total medical care costs 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: 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 Property Subject to or Available for Operating Lease [Axis] Property Subject to or Available for Operating Lease [Axis] Property Subject to or Available for Operating Lease [Domain] Property Subject to or Available for Operating Lease [Domain] Property Subject to Operating Lease Property Subject to Operating Lease [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] 6th & Pine Development, LLC 6th & Pine Development, LLC [Member] 6th & Pine Development, LLC [Member] Sale Leaseback Transaction, Description [Axis] Sale Leaseback Transaction, Description [Axis] Sale Leaseback Transaction, Name [Domain] Sale Leaseback Transaction, Name [Domain] Molina Center And Ohio Exchange Molina Center And Ohio Exchange [Member] Molina Center And Ohio Exchange [Member] Debt Commitment Letter Debt Commitment Letter [Member] Debt Commitment Letter [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Letter of Credit Letter of Credit [Member] Interest expense under leases Interest Expense, Lessee, Assets under Capital Lease Annual increase in rental payment Sale Leaseback Transaction, Annual Rental Payments Increase Percentage Sale Leaseback Transaction, Annual Rental Payments Increase Percentage Number of extensions available (in extension) Sale Leaseback Transaction, Number Of Extension Sale Leaseback Transaction, Number Of Extension Lease renewal terms Sale Leaseback Transaction, Lease Renewal Term Sale Leaseback Transaction, Lease Renewal Term Number of properties Number of Property Leased Number of Property Leased Annual increase in rental payment Operating Leases, Annual Rental Payments Increase Percentage Operating Leases, Annual Rental Payments Increase Percentage Number of renewal term Lessor, Operating Lease, Renewal Term Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Adjustments to reconcile net (loss) income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Deferred income taxes Increase (Decrease) in Deferred Income Taxes Share-based compensation Share-based Compensation Non-cash restructuring charges 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 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 Deferred Revenue Income taxes Increase (Decrease) in Income Taxes Payable Net cash provided by operating activities Proceeds from sales and maturities of investments Proceeds from employee stock plans Supplemental cash flow information: Supplemental Cash Flow Information [Abstract] Income taxes Income Taxes Paid, Net Interest Interest Paid Schedule of non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Issuance of common stock in exchange for 1.625% Convertible Notes Notes Issued Component of 1.625% Convertible 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 Common stock used for stock-based compensation Stock Issued Details of business combinations: Details of Business Combinations Abstract Details of business combinations: Fair value of assets acquired Fair Value of Assets Acquired Fair value of liabilities assumed Liabilities Assumed Payable to seller Business Combination, Purchase Price Amounts Accrued (Received) Business Combination, Purchase Price Amounts Accrued (Received) Amounts advanced for acquisitions Business Combination, Prepaid Consideration Transferred Business Combination, Prepaid Consideration Transferred 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 Income Taxes Income Tax Disclosure [Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Exercise Price Range [Axis] Exercise Price Range [Axis] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] Share-based Compensation, Shares Authorized under Stock Option Plans, 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 Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Summarized premium revenue Summarized Premium Revenue [Table Text Block] summarized premium revenue. Receivables (payables) for 3R programs Affordable Care Act, Premium Stabilization Programs, Receivables And Payables [Table Text Block] Affordable Care Act, Premium Stabilization Programs, Receivables and Payables [Table Text Block] Quality incentive premium revenue recognized Quality Incentive Premium Revenue Recognized [Table Text Block] Quality incentive premium revenue recognized. Consolidated medical care costs Schedule Of Health Care Organization Cost [Table Text Block] Schedule of health care organization cost. 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] Income tax expense (benefit) from change in tax rate Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Amount of reasonable estimate for income tax expense (benefit) from effect of Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete. 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] Federal Domestic Tax Authority [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Income tax expense (benefit) Net operating loss carryforwards Operating Loss Carryforwards Tax credit carryovers Tax Credit Carryforward, Amount Excess tax benefits from share-based compensation Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net Deferred tax assets Tax Credit Carryforward, Valuation Allowance Increase in deferred tax asset valuation allowance Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount 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 Operating segment information Schedule of Segment Reporting Information, by Segment [Table Text Block] Deferred contract costs Deferred Contract Costs [Member] Deferred Contract Costs [Member] Amortization of capitalized software Depreciation And Amortization Of Capitalized Software Depreciation, and amortization of capitalized software. Depreciation of property and equipment Depreciation Amortization of intangible assets Amortization of Intangible Assets Depreciation and amortization Depreciation and Amortization, Continuing Operations Depreciation and Amortization, Continuing Operations Recorded in cost of service revenue: Cost of Services, Amortization Other Amortization of Other Deferred Charges Depreciation and amortization reported in the statement of cash flows Cost of Goods Sold, Depreciation and Amortization 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 Current assets: Cash and cash equivalents Deferred contract costs Costs in Excess of Billings, Noncurrent Restricted investments Restricted Investments, Noncurrent Other assets Other Assets, Noncurrent LIABILITIES AND STOCKHOLDERS’ EQUITY Amounts due government agencies Medical Premium Liability Due To Agency Medical Premium Liability Due to Agency Deferred revenue Deferred Revenue, Current Long-term debt Long-term Debt and Capital Lease Obligations Total stockholders' equity Pacific Healthcare IPA Affiliated Entity [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Provider Agreement with Pacific Healthcare IPA Provider Agreement With Pacific Healthcare IPA [Member] Provider Agreement With Pacific Healthcare IPA [Member] Receivable from related party Due from Related Parties Ownership percentage Equity Method Investment, Ownership Percentage Payments under provider agreement Related Party Transaction, Amounts of Transaction Effective income tax rate reconciliation to the statutory federal income tax rate Effective Income Tax Rate Reconciliation, Amount [Abstract] 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 Compensation Cost, Percent Nondeductible goodwill impairment Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Percent Revaluation of net deferred tax assets Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Change in purchase agreement that increased tax basis in assets Effective Income Tax Rate Reconciliation, Change In Tax Basis Of Assets Acquired Effective Income Tax Rate Reconciliation, Change In Tax Basis Of Assets Acquired Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Effective tax (benefit) rate Effective Income Tax Rate Reconciliation, Percent Investments Marketable Securities [Table Text Block] Schedule of Financing Receivables Past Due Schedule of Financing Receivables Past Due [Table] Michigan MICHIGAN South Carolina SOUTH CAROLINA Texas TEXAS Utah UTAH Washington WASHINGTON Wisconsin WISCONSIN Other Other Health Plan [Member] Other health plan. Financing Receivable, Recorded Investment, Past Due [Line Items] Financing Receivable, Recorded Investment, Past Due [Line Items] Summary of accounts receivable Receivables, Net, Current [Abstract] Total receivables Postemployment Benefits [Abstract] Employee Benefits Compensation and Employee Benefit Plans [Text Block] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Medical Premium Liability Due to Agency Medical Premium Liability Due to Agency [Member] Medical Premium Liability Due to Agency [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 Medical premium liability based on medical costs threshold Medical Premiums Liability, Medical Care Costs Threshold Medical Premiums Liability, Medical Care Costs Threshold Accounts payable Risk corridor payments not yet recorded Affordable Care Act, Premium Stabilization Program, Risk Corridor, Receivable (Payable), Not Yet Recorded Affordable Care Act, Premium Stabilization Program, Risk Corridor, Receivable (Payable), Not Yet Recorded Percentage of additional incremental revenue earned Percentage Of Additional Incremental Revenue Earned Percentage of additional incremental revenue earned. Medical administrative costs Medical Administrative Costs Medical administrative costs. Premium deficiency recorded Health Care Reform, Premium Deficiency Reserve Health Care Reform, Premium Deficiency Reserve Additional medical care costs incurred, due to federal government ceasing payments Additional Medical Care Costs Incurred Additional Medical Care Costs Incurred 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] Amortized Cost Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract] Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis Due after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis Due after five years through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis Estimated Fair Value Available-for-sale Securities, Debt Maturities, Single Maturity Date [Abstract] Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Due after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value Due after five years through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value Estimated Fair Value Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value Restructuring and Separation Costs Restructuring and Related Activities Disclosure [Text Block] 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] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Bridge Credit Agreement Bridge Credit Agreement [Member] Bridge Credit Agreement [Member] Face amount of debt Debt Instrument, Face Amount Proceeds used for working capital and acquisition financings Debt Instrument, Proceeds Used for Working Capital and Acquisition Financings Debt Instrument, Proceeds Used for Working Capital and Acquisition Financings Future reduction to face amount Debt Instrument, Future Reduction to Face Amount Debt Instrument, Future Reduction to Face Amount Condensed Income Statement [Table] Condensed Income Statement [Table] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Revenue: Other income, net Net loss before equity in net income 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 (loss) income of subsidiaries Income (Loss) from Subsidiaries, Net of Tax Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Historical goodwill Goodwill, Gross Accumulated impairment losses Goodwill, Impaired, Accumulated Impairment Loss Changes in the carrying amount of goodwill Goodwill [Roll Forward] Beginning balance Goodwill Impairment losses, year ended December 31, 2017 Ending balance 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. 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. Summarized premium revenue Health Care Organization, Revenue [Abstract] Premium revenue percentage Health Care Organization, Revenue Percentage Health Care Organization, Revenue Percentage 5.375% Senior Notes due 2022 Principal amount Increase (Decrease) of Restricted Investments Available-for-sale securities Line of Credit Facility [Table] Line of Credit Facility [Table] Revolving Credit Facility Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Line of credit, current Line of Credit, Current Amount outstanding under Letter of Credit Long-term Line of Credit Current borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity 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 Compensation, Stock Options, Activity [Table Text Block] Stock Option Plans, by Exercise Price Range Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block] Summary of accounts receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Supplemental Condensed Consolidating Financial Information Condensed Financial Statements [Text Block] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Condensed Statements of Income Management fees Management Fees Revenue Investment income and other revenue Investment Income, Net Expenses: Operating Expenses [Abstract] Other income Loss before income taxes and equity in net income of subsidiaries Loss Before Income Taxes And Equity In Net Income Of Subsidiaries Loss before income taxes and equity in net income of subsidiaries. Operating Segments Operating Segments [Member] Other Operating Segment Reconciling Items [Member] Total gross margin Other operating revenues Other operating expenses Operating income Other expenses, net Segment Information Segment Reporting Disclosure [Text Block] Condensed Balance Sheets Condensed Balance Sheet [Table Text Block] Condensed Statements of Income Condensed Income Statement [Table Text Block] Condensed Statements of Comprehensive (Loss) Income Comprehensive Income (Loss) [Table Text Block] Condensed Statements of Cash Flows Condensed Cash Flow Statement [Table Text Block] Condensed Financial Statements [Table] Percentage of contractual interest rate on Notes Condensed Consolidating Statements of Income Condensed Consolidating Statements of Comprehensive Income Condensed Statement of Comprehensive Income [Table Text Block] Condensed Consolidating Balance Sheet Condensed Consolidating Statements of Cash Flow Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Income Captions [Line Items] Condensed Statement of Income Captions [Line Items] Other comprehensive income (loss), net of tax Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] New Mexico Data Center New Mexico Data Center [Member] New Mexico data center. Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Payments for purchase of assets Payments for Purchase of Other Assets Administrative fee revenue Administrative Services Revenue Amount paid for health care services Variable Interest Entity, Financial or Other Support, Amount Variable interest entity, total assets Variable Interest Entity, Consolidated, Carrying Amount, Assets Variable interest entity, total liabilities Variable Interest Entity, Consolidated, Carrying Amount, Liabilities Tax credit claimed as a percentage of original investment amount Tax Credit Claimed As Percentage Of Original Investment Amount Tax credit claimed as percentage of original investment amount. Tax credit claimed, term Tax Credit Claimed, Term Tax Credit Claimed, Term Percentage of credit claimed for first three years Percentage of credit claimed for first three years Percentage of credit claimed for first three years. Percentage of credit claimed for remaining four years Percentage Of Credit Claimed For Each Of Remaining Four Years Percentage of credit claimed for each of remaining four years. Capital contribution by related party Capital Contribution by Related Party Capital contribution by related party. Principal amount of loan by party Principal Amount Of Loan By Party Principal amount of loan by party. Proceeds from other debt Proceeds from Other Debt Risk adjustment payable, Current Benefit Year Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable (Payable), Current Year Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable (Payable), Current Year Risk adjustment payable, Prior Benefit Years Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable (Payable), Prior Years Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable (Payable), Prior Years Risk adjustment payable, Total Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable (Payable) Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable (Payable) Reinsurance receivable, Current Benefit Year Affordable Care Act, Premium Stabilization Program, Reinsurance, Receivable (Payable), Current Year Affordable Care Act, Premium Stabilization Program, Reinsurance, Receivable (Payable), Current Year Reinsurance receivable, Prior Benefit Years Affordable Care Act, Premium Stabilization Program, Reinsurance, Receivable (Payable), Prior Years Affordable Care Act, Premium Stabilization Program, Reinsurance, Receivable (Payable), Prior Years Reinsurance receivable, Total Affordable Care Act, Premium Stabilization Program, Reinsurance, Receivable (Payable) Affordable Care Act, Premium Stabilization Program, Reinsurance, Receivable (Payable) Risk corridor payable, Current Benefit Year Affordable Care Act, Premium Stabilization Program, Risk Corridor, Receivable (Payable), Current Year Affordable Care Act, Premium Stabilization Program, Risk Corridor, Receivable (Payable), Current Year Risk corridor payable, Prior Benefit Years Affordable Care Act, Premium Stabilization Program, Risk Corridor, Receivable (Payable), Prior Years Affordable Care Act, Premium Stabilization Program, Risk Corridor, Receivable (Payable), Prior Years Risk corridor payable, Total Affordable Care Act, Premium Stabilization Program, Risk Corridor, Receivable (Payable) Affordable Care Act, Premium Stabilization Program, Risk Corridor, Receivable (Payable) Minimum MLR payable, Current Benefit Year Affordable Care Act, Premium Stabilization Program, Minimum Medical Loss Ratio, Receivable (Payable), Current Year Affordable Care Act, Premium Stabilization Program, Minimum Medical Loss Ratio, Receivable (Payable), Current Year Minimum MLR payable, Prior Benefit Years Affordable Care Act, Premium Stabilization Program, Minimum Medical Loss Ratio, Receivable (Payable), Prior Years Affordable Care Act, Premium Stabilization Program, Minimum Medical Loss Ratio, Receivable (Payable), Prior Years Minimum MLR payable, Total Affordable Care Act, Premium Stabilization Program, Minimum Medical Loss Ratio, Receivable (Payable) Affordable Care Act, Premium Stabilization Program, Minimum Medical Loss Ratio, Receivable (Payable) Derivative [Table] Derivative [Table] 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 Numerator: Net Income (Loss) Attributable to Parent [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] Common stock offering (in shares) Weighted Average Number of Shares Issued, Basic Denominator for basic net (loss) income per share (in shares) Effect of dilutive securities: Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] Share-based compensation (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Convertible senior notes (in shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities 1.125% Warrants (in shares) Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants Denominator for diluted net (loss) income per share (in shares) Net (loss) income per share: Earnings Per Share, Basic and Diluted [Abstract] 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] 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 [Member] Cash Convertible Senior Notes Due 2020, Warrants [Member] Cash Convertible Senior Notes Due 2020, Warrants [Member] 1.125% Warrants 1.125% Warrants [Member] 1.125% Warrants [Member] 1.625% Notes 1.625% Notes [Member] 1.625% 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 Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Stated interest rate Class Of Warrant Or Right, Stated Interest Rate Class Of Warrant Or Right, Stated Interest Rate Quarterly Financial Information Disclosure [Abstract] Quarterly Results of Operations (Unaudited) Quarterly Financial Information [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] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [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] Eligible Item or Group for Fair Value Option [Axis] Financial Instrument [Axis] Fair Value, Option, Eligible Item or Group [Domain] Financial Instruments [Domain] Government-sponsored enterprise securities (GSEs) 1.125% Call Option derivative asset Derivative Financial Instruments, Assets [Member] Fair value of assets measured on recurring basis Assets, Fair Value Disclosure [Abstract] Total assets measured at fair value on a recurring basis Assets, Fair Value Disclosure 1.125% Conversion Option derivative liability Derivative Liability Total liabilities measured at fair value on a recurring basis Financial and Nonfinancial Liabilities, Fair Value Disclosure 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 - Earned current period Amount Of Current Year Quality Incentive Premium Revenue Recognized Amount of current year quality incentive premium revenue recognized. Amount of quality incentive premium revenue recognized in current period - 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 Property, Equipment, and Capitalized Software, Net Property, Plant and Equipment Disclosure [Text Block] 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 Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block] Property, equipment, and capitalized software, net Intangible assets, net Finite-Lived Intangible Assets, Net Goodwill Long-term debt Lease financing obligations Preferred stock, $0.001 par value; 20 shares authorized, no shares issued and outstanding Additional paid-in capital Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Error Corrections and Prior Period Adjustments Restatement [Line Items] Error Corrections and Prior Period Adjustments Restatement [Line Items] Summary of quarterly results of operations Selected Quarterly Financial Information [Abstract] Net income per share: Increase to gross profit Summary of quarterly results of operations Quarterly Financial Information [Table Text Block] 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) Total provision for income taxes Schedule of Held-to-maturity Securities Schedule of Held-to-maturity Securities [Table] Other Schedule of Held-to-maturity Securities [Line Items] Schedule of Held-to-maturity Securities [Line Items] Summary of restricted investments by health plan Restricted Cash and Investments, Noncurrent [Abstract] Restricted investments by health plan Debt Long-term Debt [Text Block] Customer relationships Customer Relationships [Member] Provider network Provider Networks [Member] Provider networks. Intangible Assets, Net (Excluding Goodwill) [Abstract] Intangible Assets, Net (Excluding Goodwill) [Abstract] Cost Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Carrying Amount Restructuring Costs Restructuring and Related Costs [Table Text Block] Restructuring Reserve Schedule of Restructuring Reserve by Type of Cost [Table Text Block] Increase in expected restructuring costs Restructuring Reserve, Period Increase (Decrease) 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 Medical Care Costs Health Care Organization, Expenses, Gross [Abstract] Fee-for-service Health Care Organization Expenses Servicing Cost Health care organization expenses fee for service costs. Pharmacy Health Care Organization, Medical Supplies and Drugs Expense Capitation Health Care Organization Expenses Capitation Costs Health care organization expenses capitation costs. Direct delivery Health Care Organization, Direct Delivery Expense Health Care Organization, Direct Delivery Expense Other Health Care Organization Expenses Other Costs Health care organization expenses other costs. Total Health Care Organization, Expenses, Gross Medical Care Costs, PMPM Health Care Organization, Expenses, Per Member Per Month [Abstract] Health Care Organization, Expenses, Per Member Per Month [Abstract] Fee-for-service (per member per month) Health Care Organization Expenses Servicing Cost, Per Member Per Month Health Care Organization Expenses Servicing Cost, Per Member Per Month Pharmacy (per member per month) Health Care Organization, Medical Supplies and Drugs Expense, Per Member Per Month Health Care Organization, Medical Supplies and Drugs Expense, Per Member Per Month Capitation (per member per month) Health Care Organization Expenses Capitation Costs, Per Member Per Month Health Care Organization Expenses Capitation Costs, Per Member Per Month Direct delivery (per member per month) Health Care Organization, Direct Delivery Expense, Per Member Per Month Health Care Organization, Direct Delivery Expense, Per Member Per Month Other (per member per month) Health Care Organization Expenses Other Costs, Per Member Per Month Health Care Organization Expenses Other Costs, Per Member Per Month Total (per member per month) Health Care Organization, Expenses, Gross, Per Member Per Month Health Care Organization, Expenses, Gross, Per Member Per Month Medical Care Costs, Percentage Health Care Organization, Expenses, Percentage [Abstract] Health Care Organization, Expenses, Percentage [Abstract] Percentage of total in Fee for service Percentage Of Fee For Service Percentage of fee for service. Percentage of total in pharmacy Percentage Of Pharmacy Percentage of pharmacy. Percentage of total in capitation Percentage Of Capitation Percentage of capitation. Percent of total in direct delivery Percent of Direct Delivery Percent of Direct Delivery Percentage of total in other Percentage Of Other Percentage of other. Percentage of total Percentage Of Medical Costs Percentage of medical costs. 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. Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block]