Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Receivable Type [Axis] Receivable Type [Axis] Risk adjustment, net payable, prior year Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Net (Payable) Receivable, Prior Years Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Net (Payable) Receivable, Prior Years Other expense (income), net Other Nonoperating Income (Expense) Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Stock options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Estimated Fair Value Debt Securities, Available-For-Sale, Unrealized Loss Position [Abstract] Debt Securities, Available-For-Sale, Unrealized Loss Position [Abstract] Accounts payable, accrued liabilities and other Increase (Decrease) in Accounts Payable and Accrued Liabilities Medical claims and benefits payable Total Medical claims and benefits payable, beginning balance Medical claims and benefits payable, ending balance Liability for Claims and Claims Adjustment Expense Other Other Claims Payable Other Claims Payable Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Estimated Fair Value Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract] Segments [Axis] Segments [Axis] Magellan complete care Magellan Complete Care [Member] Magellan Complete Care [Member] Vested (in dollars 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 1.125% Warrants Cash Convertible Senior Notes Due 2020, Warrants [Member] Cash Convertible Senior Notes Due 2020, Warrants [Member] Deferred debt issuance costs Debt Issuance Costs, Noncurrent, Net (Level 3) Fair Value, Inputs, Level 3 [Member] Proceeds from sales and maturities of investments Proceeds from Sale and Maturity of Marketable Securities Common stock purchases (in shares) Shares repurchased (in shares) Stock Repurchased During Period, Shares Call option derivative asset Derivative Asset Due after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Statistical Measurement [Domain] Statistical Measurement [Domain] LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Term loan facility Line of Credit [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Risk adjustment receivable Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable HIF liabilities Health Care Insurance, Fee, Liability Health Care Insurance, Fee, Liability Amounts due government agencies Amounts due government agencies Medical Premium Liability Due To Agency Medical Premium Liability Due to Agency Current Fiscal Year End Date Current Fiscal Year End Date Estimated Fair Value Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value Cash received for partial settlement of call option Cash received for settlement of call option Proceeds from Convertible Debt Cash paid for partial termination of warrants Cash paid for partial termination of 1.125% Warrants Payments for Repurchase of Warrants Operating income Operating income Operating Income (Loss) Entity Address, Postal Zip Code Entity Address, Postal Zip Code Total current liabilities Liabilities, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Begining Balance (in dollars per share) Ending Balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Maine Community Health Options v. United States Maine Community Health Options v. United States [Member] Maine Community Health Options v. United States [Member] Common stock purchases Common stock purchases Payments for Repurchase of Common Stock ASSETS Assets [Abstract] Accounting Policies [Abstract] Accounting Policies [Abstract] Share-based compensation Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Entity Shell Company Entity Shell Company Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Total Quality Incentive Premium Revenue Recognized Quality incentive premium revenue recognized. 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Subsequent Event Type [Axis] Subsequent Event Type [Axis] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Entity Small Business Entity Small Business Less: effect of income taxes OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Class of Warrant or Right [Axis] Class of Warrant or Right [Axis] Concentrations of Credit Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Interest expense Interest Expense Depreciation and amortization Depreciation, Depletion and Amortization Entity Filer Category Entity Filer Category Unrealized Losses Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] Mortgage-backed securities Mortgage-backed securities Commercial Mortgage Backed Securities [Member] Total liabilities Liabilities Entity Address, City or Town Entity Address, City or Town Quality incentive premium revenue recognized in current period: Quality Incentive Premium Revenue Recognized [Abstract] Quality Incentive Premium Revenue Recognized [Abstract] Your care health plan inc Your Care Health Plan Inc [Member] Your Care Health Plan Inc Weighted average period for recognition Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Other Other Segments [Member] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] (Level 1) Fair Value, Inputs, Level 1 [Member] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Number of states in which entity operates (in state) Number of States in which Entity Operates Document Fiscal Year Focus Document Fiscal Year Focus In a Continuous Loss Position for Less than 12 Months Debt Securities, Available-for-sale, 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activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] In a Continuous Loss Position for Less than 12 Months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions Litigation Case [Axis] Litigation Case [Axis] In a Continuous Loss Position for 12 Months or More Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions 4.375% Notes 4.375% Senior Notes [Member] 4.375% Senior Notes Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Total paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Term loan facility Credit facility Revolving Credit Facility [Member] Current assets: Prepaid expenses and other current assets Current Assets [Member] Current Assets [Member] Subsequent event Subsequent Event [Member] Net purchase price Payments to Acquire Businesses, Net of 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Revenue Recognized [Table Text Block] Quality incentive premium revenue recognized. Maximum available quality incentive premium - current period Maximum Available Quality Incentive Premium Current Year Maximum available quality incentive premium current year. Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Termination of warrants Adjustments to Additional Paid in Capital, Other Schedule of Cash and Cash Equivalents Schedule of Cash and Cash Equivalents [Table Text Block] Gross unrealized losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Payments for medical care costs related to: Payments For Medical Care Costs [Abstract] Payments for medical care costs. Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Due in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Other comprehensive income, net of tax Other comprehensive income (loss), net Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent In a Continuous Loss Position for 12 Months or More Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Health insurer fees reimbursed Health Care Organization, Insurer Fee Revenue Health Care Organization, Insurer Fee Revenue Warrants outstanding (in shares) Class of Warrant or Right, Outstanding Derivative assets Derivative Asset, Fair Value, Gross Asset Income taxes Increase (Decrease) in Income Taxes Payable Other expenses, net: Nonoperating Income (Expense) [Abstract] Capitation payable Capitation Claims Payable Capitation Claims Payable Face amount Debt Instrument, Face Amount Due after five years through ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 (Level 2) Fair Value, Inputs, Level 2 [Member] Other Amounts Due To Government Agencies, Medicaid, Other Amounts Due To Government Agencies, Medicaid, Other Prior years Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Equity [Abstract] Equity [Abstract] Total Assets, Fair Value Disclosure Receivables Increase (Decrease) in Receivables Schedule of non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Entity Central Index Key Entity Central Index Key Deferred revenue Contract with Customer, Liability, Current Entity Emerging Growth Company Entity Emerging Growth Company Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Credit Facility [Domain] Credit Facility [Domain] Denominator for net income per share, diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Derivative Contract [Domain] Derivative Contract [Domain] Litigation Case [Domain] Litigation Case [Domain] Basic (in dollars per share) Earnings Per Share, Basic Debt net of unamortized debt discount Long-Term Debt, Noncurrent, Net Of Unamortized Debt Discount Long-Term Debt, Noncurrent, Net Of Unamortized Debt Discount Risk adjustment and Part D risk sharing Amounts Due to Government Agencies, Risk Adjustment and Part D risk sharing Amounts Due to Government Agencies, Risk Adjustment and Part D risk sharing Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Debt Disclosure [Abstract] Debt Disclosure [Abstract] Common stock, $0.001 par value, 150 million shares authorized; outstanding: 59 million shares at June 30, 2020, and 62 million shares at December 31, 2019 Common Stock, Value, Outstanding Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Consolidated net leverage ratio Consolidated Net Leverage Consolidated Net Leverage Balance Sheet Location [Axis] Balance Sheet Location [Axis] Schedule of receivables Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Minimum MLR and profit sharing Amounts Due To Government Agencies, Medicare, Medical Loss Ratio And Profit Sharing, Threshold Amounts Due To Government Agencies, Medicare, Medical Loss Ratio And Profit Sharing, Threshold Change in non-risk and other provider payables Medical Claims And Benefits Payable, Adjustments, Change In Provider Medical Claims and Benefits Payable, Adjustments, Change in Provider Receivable [Domain] Receivable [Domain] Goodwill and intangible assets, net Intangible Assets, Net (Including Goodwill) Other Liabilities Disclosure [Abstract] Other Liabilities Disclosure [Abstract] 4.875% Notes 4.875% Notes due 2025 4.875% Senior Notes [Member] 4.875% Senior Notes [Member] Share-based compensation (in shares) Number of common stock issued (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Granted (in dollars 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 Stock purchases (in shares) Weighted Average Number of Shares, Common Stock Subject to Repurchase or Cancellation Investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Swingline sub facility Swingline Sub Facility [Member] Swingline Sub Facility Earned prior periods Amount Of Quality Incentive Premium Revenue Recognized From Prior Year Amount of quality incentive premium revenue recognized from prior year. 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Premium tax revenue Health Care Organization, Premium Tax Revenue Health Care Organization, Premium Tax Revenue Total Number of Positions Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract] Equity Component [Domain] Equity Component [Domain] Entity Address, Address Line One Entity Address, Address Line One Gross margin Gross Profit Premium tax expenses Premium Tax Expenses An assessment levied by a state government on the net premium income collected. Premium Revenue and Contractual Provisions That May Adjust or Limit Revenue or Profit Revenue from Contract with Customer [Policy Text Block] Net income Net income Net Income (Loss) Attributable to Parent Entity Address, State or Province Entity Address, State or Province Finance lease liabilities Finance Lease, Liability, Noncurrent Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Other Other Securities [Member] Other Securities Debt net of unamortized discount Long-Term Debt, Current Maturities, Net Of Unamortized Premium (Discount) Long-Term Debt, Current Maturities, Net Of Unamortized Premium (Discount) Due after ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Medicare program: Amounts Due To Government Agencies Medicare Program [Abstract] Amounts Due To Government Agencies Medicare Program Due after one year through five years Debt Securities, 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