Unbilled Unbilled Unbilled amounts due for services rendered, net of customer prepayments of unbilled amounts. Accounting Policies Significant Accounting Policies [Text Block] Workers' Compensation Expense Workers' Compensation Expense Expense accrued pertaining to workers compensation costs. Document Quarterly Report Document Quarterly Report Range [Domain] Statistical Measurement [Domain] Assets, Fair Value Disclosure Assets, Fair Value Disclosure Debt Securities, Available-for-sale Debt Securities, Available-for-Sale [Table Text Block] Entity Listings, Exchange [Axis] Entity Listings, Exchange [Axis] Accrued worksite employee payroll cost Accrued worksite employee payroll costs Total of the carrying values as of the balance sheet date of obligations incurred through that date and payable for obligations related to services received from employees, including accrued salaries and bonuses. Entity File Number Entity File Number Additional Paid-In Capital [Member] Additional Paid-in Capital [Member] Revenues Comprise of Gross Billings and WSEE Payroll Cost [Table] Revenues Comprised of Gross Billings and WSEE Payroll Cost [Table Text Block] Revenues are comprised of gross billings less WSEE payroll costs as follows Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount New Accounting Pronouncements, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Proceeds from Sale of Property, Plant, and Equipment [Abstract] Proceeds from Sale of Property, Plant, and Equipment [Abstract] Client funds liability and other Proceeds from (Payment for) Other Financing Activity Activity and balances related to incurred but not paid workers' compensation claims Schedule of Accrued Workers Compensation Claims [Table Text Block] Disclosure of the incurred but not yet paid workers' compensation claims activities and balances. Interest income Interest Income, Other Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Basic net income per share of common stock (in dollars per share) Earnings Per Share, Basic Commissions Sales Commissions and Fees Advertising Advertising Expense Accounts payable Increase (Decrease) in Accounts Payable, Trade Payroll Withholdings Included in Cash Balance Payroll Withholdings Included in Cash Balance Withholdings associated with liabilities related to taxes and payroll deductions which is included in the cash balance. Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Deposits – health insurance Deposits health insurance Carrying value of amounts transferred to third party health care providers for security purposes that are expected to be returned or applied towards payment after one year or beyond the operating cycle, if longer. Accrued worksite employee payroll costs Increase (Decrease) in WSEE payroll expense the increase (decrease) during the period in accrued worksite employee ("WSEE") payroll expense Time period estimate of incurred claim costs to be paid included in long term liabilities Time period estimate of incurred claim costs to be paid included in long term liabilities Time period estimate of incurred claim costs to be paid included in long-term liabilities. Summary of investments in cash, cash equivalents and marketable securities Schedule of Cash and Cash Equivalents [Table Text Block] Stock-based compensation Share-Based Payment Arrangement, Noncash Expense Health Insurance Costs [Abstract] Health Insurance Costs [Abstract] Accrued health insurance costs Accrued health insurance costs Carrying value as of the balance sheet date of obligations and payables pertaining to premiums or costs incurred of a health insurance nature. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Cash and Cash Equivalents [Member] Cash and Cash Equivalents [Member] APIC, Share-Based Payment Arrangement, Increase for Cost Recognition APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Treasury stock, at cost Treasury Stock, Value Dividends, Common Stock, Cash Dividends, Common Stock, Cash Total stockholders’ equity Balance Balance Equity, Attributable to Parent Stock-based compensation Share-Based Payment Arrangement, Expense Adjusted Term SOFR Rate Plus Applicable Margin Adjusted Term SOFR Rate Plus Applicable Margin Adjusted Term SOFR Rate Plus Applicable Margin Financial Instruments [Domain] Financial Instruments [Domain] Total liabilities and stockholders’ equity Liabilities and Equity Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Remaining Borrowing Capacity Cash and Cash Equivalent [Table] Cash and Cash Equivalent [Table] LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity [Abstract] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Cover [Abstract] Cover [Abstract] Cash and Cash Equivalents, Fair Value Disclosure Cash and Cash Equivalents, Fair Value Disclosure Maximum [Member] Maximum [Member] Minimum [Member] Minimum [Member] Accounting Policies [Abstract] Accounting Policies [Abstract] Authorized to repurchased additional shares under repurchase program (in shares) Share Repurchase Program, Remaining Authorized, Number of Shares Other Balance Sheet Information[Abstract] OtherBalanceSheetDisclosuresAbstract [Abstract] Long-Term Debt, Maturity Date Long-Term Debt, Maturity Date Deposits workers compensation Deposits workers compensation Carrying value of amounts transferred to third party workers' compensation insurance providers for security purposes that are expected to be returned or applied towards payment after one year or beyond the operating cycle, if longer. Revenue Recognition Revenue [Policy Text Block] Treasury Stock, Common Treasury Stock, Common [Member] Revolving Credit Facility Debt Disclosure [Text Block] Accounts payable Accounts Payable, Current Time period estimate of incurred claim costs to be paid included in short-term liabilities Time period estimate of incurred claim costs to be paid included in short term liabilities Time period estimate of incurred claim costs to be paid included in short-term liabilities. Workers' Compensation Costs [Abstract] Workers' Compensation Costs [Abstract] Payroll taxes and other payroll deductions payable Increase (Decrease) in Other Employee-Related Liabilities Company's maximum economic burden for the first layer of claims per occurrence Workers' Compensation, Maximum economic burden first layer of claims per occurrence The Company's maximum economic burden for the first layer of claims per occurrence. Percentage Of Subsidiary Stock Securing Debt Percentage Of Subsidiary Stock Securing Debt Percentage of subsidiary stock securing debt per debt agreements. Southwest [Member] Southwest [Member] Southwest [Member] Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Income (loss) before income tax (benefit) expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Common stock Common Stock, Value, Issued Entity Shell Company Entity Shell Company Short-term Investments Short-Term Investments WorkersCompDepositsHeldInTrust WorkersCompDepositsHeldInTrust Amount of workers' compensation - deposit funds held in trust accounts. Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Weighted Average Number of Shares Outstanding, Diluted Weighted Average Number of Shares Outstanding, Diluted Commitments and contingencies Commitments and Contingencies Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Southeast [Member] Southeast [Member] Southeast [Member] Workers' Compensation Liability Workers' Compensation Liability Workers' Compensation Liability Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Cash Cash Line of Credit Facility [Table] Line of Credit Facility [Table] Entity Small Business Entity Small Business U.S. Treasury rates that correspond with the weighted average estimated claim payout period (in hundredths) U.S. Treasury rates that correspond with the weighted average estimated claim payout period U.S. Treasury rates that correspond with the weighted average estimated claim payout period utilized to discount workers' compensation cost estimates. Marketable securities: Marketable Securities [Abstract] Drafts Payable Broker-Dealer, Draft Payable Document Transition Report Document Transition Report Proceeds from maturities Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Deferred Income Tax Liabilities, Net Deferred Income Tax Liabilities, Net Document Fiscal Period Focus Document Fiscal Period Focus Goodwill and other intangible assets, net Intangible Assets, Net (Including Goodwill) Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Accrued corporate payroll and commissions Accrued Salaries Proceeds from Lines of Credit Proceeds from Lines of Credit Company's maximum aggregate economic burden for claims in excess of 1 million per policy year Workers' Compensation, Maximum aggregate economic burden for claims in excess of first layer cap per policy year The maximum amount the Company will bear of the economic burden per policy year for those claims exceeding the first layer maximum per claim occurrence. Total assets Assets Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Trading Symbol Trading Symbol Geographical [Domain] Geographical [Domain] Entity Address, City or Town Entity Address, City or Town Document Type Document Type Net Income per Share Earnings Per Share [Text Block] Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Accounts receivable, net Accounts and Other Receivables, Net, Current Revenues Revenues Revenue from Contract with Customer, Excluding Assessed Tax Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Property and equipment purchases Payments to Acquire Property, Plant, and Equipment Workers' Compensation Discount, Changed during period Workers' Compensation Discount, Changed during period The change in worker's compensation reserve liability during the period resulting from the discount applied to reduce the reserve to present value. Total current assets Assets, Current Range [Axis] Statistical Measurement [Axis] Entity Emerging Growth Company Entity Emerging Growth Company Dividends declared per share of common stock (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage ROU assets obtained in exchange for lease obligations Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Marketable securities Marketable Securities, Current Worksite employee payroll cost Worksite employee payroll cost Payroll costs incurred (including share-based compensation) by the company's worksite employees that are directly related to services rendered by the worksite employees during the reporting period. Entity Information [Line Items] Entity Information [Line Items] Current liabilities: Liabilities, Current [Abstract] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Geographical [Axis] Geographical [Axis] Disaggregation of Revenue [Table Text Block] Disaggregation of Revenue [Table Text Block] Client Prepayments Included in Cash Balance Client Prepayments Included in Cash Balance Client prepayments included in the cash balance. Total operating expenses Operating Expenses Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Accrued workers’ compensation costs, net of current Workers' Compensation Liability, Noncurrent Workers' Compensation Liability, Noncurrent Diluted net income per share of common stock (in dollars per share) Earnings Per Share, Diluted Retained Earnings [Member] Retained Earnings [Member] Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Title of 12(b) Security Title of 12(b) Security Entity Address, Postal Zip Code Entity Address, Postal Zip Code Cash, cash equivalents, restricted cash, funds held for clients, and deposits - workers’ compensation beginning of period Cash, cash equivalents, restricted cash, funds held for clients, and deposits - workers’ compensation end of period Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Total Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Accrued corporate payroll, commissions and other accrued liabilities Increase (Decrease) in Accrued Salaries Income Statement [Abstract] Income Statement [Abstract] Payroll taxes and other payroll deductions payable Accrued Payroll Taxes, Current Income tax (benefit) expense Income Tax Expense (Benefit) Gross billings Gross billings The company's revenues are derived from its gross billings, which are based on the payroll cost of its worksite employees and a markup computed as a percentage of the payroll costs. Debt Instrument, Basis Spread on Variable Rate Debt Instrument, Basis Spread on Variable Rate Prepaid insurance and related assets Prepaid Insurance Purchases Payments to Acquire Marketable Securities Earnings Per Share [Abstract] Earnings Per Share [Abstract] WorkersCompensationLiabilityNetOfAdminFeesCurrent WorkersCompensationLiabilityNetOfAdminFeesCurrent Carrying value as of the balance sheet date of obligations and payables pertaining to claims incurred of a workers compensation nature net of administrative fees. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer) net of administrative fees. Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Prepaid insurance and related assets Increase (Decrease) in Prepaid Expense Cash, Cash Equivalents, and Short-term Investments Cash, Cash Equivalents, and Short-Term Investments Funds Held for Clients Funds Held for Clients Incurred but not paid workers compensation liabilities [Abstract] Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract] Accrued workers’ compensation costs Increase (Decrease) in Workers' Compensation Liabilities Gross profit Gross Profit Restricted Cash and Cash Equivalents Items [Line Items] Organization, Consolidation and Presentation of Financial Statements [Abstract] Other current assets Increase (Decrease) in Other Current Assets Stockholders' Equity, Other Stockholders' Equity, Other Income taxes payable/receivable Increase (Decrease) in Income Taxes City Area Code City Area Code Cash and Cash Equivalents [Line Items] Cash and Cash Equivalents [Line Items] Undiscounted accrued workers' compensation costs Undiscounted Accrued Workers Compensation Costs The liability as of the balance sheet date representing required funding mandated by statute or regulatory authority that is related directly or indirectly to underwriting activities, including pools for self-insurance and excluding premium taxes and income taxes. The funds derived from the assessments generally enable a government guarantor to pay insurance claims in the event that the underwriting insurer is insolvent or otherwise unable to meet its payment obligations. Applicable Margin Federal Funds Rate Applicable Margin Federal Funds Rate Applicable margin to the federal funds rate for alternate base rate borrowings. Client funds liability and other accrued liabilities Accrued Liabilities, Current Shares repurchased under the program (in shares) Treasury Stock, Shares, Acquired West [Member] West [Member] West [Member] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Cash flows from investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] General and administrative expenses General and Administrative Expense Net cash used in operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Benefits costs incurred (reduced) related to run-off BenefitsCostsIncurred(Reduced)RelatedtoRun-off Benefits costs incurred (reduced) for changes in estimated run-off of claims. Stockholders Equity Equity [Text Block] Aggregate number of shares repurchased during the period (in shares) Aggregate number of shares repurchased during the period Aggregate number of shares repurchased during the period. Proceeds from dispositions Proceeds from Sale of Debt Securities, Available-for-Sale Current borrowing capacity Line of Credit Facility, Current Borrowing Capacity Net income (loss) Net income Net Income (Loss) Attributable to Parent Noncurrent liabilities: Liabilities, Noncurrent [Abstract] Money Market Funds [Member] Money Market Funds [Member] Prepaid health insurance current Prepaid health insurance current Carrying amount as of the balance sheet date for portion of health insurance contract to be utilized in one year of less. Prepaid health insurance Required accumulated cash surplus Prepaid health insurance noncurrent Carrying amount as of the balance sheet date for portion of health insurance contract to be utilized over longer than one year. Time period incurred claims expected to be paid recorded as restricted cash Time period incurred claims expected to be paid recorded as restricted Time period incurred claims expected to be paid recorded as restricted. Workers compensation administrative fees accrued Workers' compensation administrative fees accrued Carrying value as of the balance sheet date of workers' compensation administrative fees. Statement, Equity Components [Axis] Equity Components [Axis] Property and equipment, net of accumulated depreciation Property, Plant and Equipment, Net Purchase of treasury stock Payments for Repurchase of Common Stock Accrued workers’ compensation costs Workers' Compensation Liability, Current Base Rate [Member] Base Rate [Member] Accounts receivable Increase (Decrease) in Accounts Receivable Number of Reportable Segments Number of Reportable Segments Entity Current Reporting Status Entity Current Reporting Status Operating income (loss) Operating Income (Loss) Debt Securities, Available-for-sale, Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost Retained earnings Retained Earnings (Accumulated Deficit) Restrictions on Cash and Cash Equivalents Restrictions on Cash and Cash Equivalents [Table Text Block] Entity Address, State or Province Entity Address, State or Province Fair Value Measurement, Policy Fair Value Measurement, Policy [Policy Text Block] Financial Instrument [Axis] Financial Instrument [Axis] Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Noncash Item [Abstract] Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Noncash Item [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Total current liabilities Liabilities, Current Decrease Increase in accrued workers' compensation costs for changes in estimated losses Decrease Increase in accrued workers' compensation costs for changes in estimated losses The decrease or increase in workers' compensation claims cost estimates for changes in the actuarial assumptions resulting from changes in actual claims experience and other trends. Net decrease in cash, cash equivalents, restricted cash, funds held for clients, and deposits – workers’ compensation Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation Accrued health insurance costs Increase (Decrease) in Health Care Insurance Liabilities Payroll taxes, benefits and workers’ compensation costs Payroll taxes, benefits and workers' compensation costs Includes payroll taxes, benefits, workers compensation costs, and other costs incurred by or directly on behalf of customers and the associated worksite employees of the customers. US Government Securities, at Carrying Value Other Cash Equivalents, at Carrying Value Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments, Policy [Policy Text Block] Interest expense Interest Expense, Operating and Nonoperating Current Fiscal Year End Date Current Fiscal Year End Date Percentage of our health insurance coverage provided by United Percentage of our health insurance coverage provided by United Percentage of our health insurance coverage provided by United Dividends paid Payments of Ordinary Dividends, Common Stock Payments of Ordinary Dividends, Common Stock Funds held for clients and other current assets Other Assets, Current Overnight Holdings Money Market Funds, Overnight Holdings, at Carrying Value Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, these investments are only held overnight. Additional paid-in capital Additional Paid in Capital, Common Stock Entities [Table] Entities [Table] Liability for Unpaid Claims and Claims Adjustment Expense, Adjustments Liability for Unpaid Claims and Claims Adjustment Expense, Adjustments Net cash provided by (used in) investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Statement [Table] Statement [Table] Northeast [Member] Northeast [Member] Northeast [Member] Deferred income taxes Deferred Income Tax Expense (Benefit) Adjustments to reconcile net income to net cash used in operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Cash flows from financing activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Document Fiscal Year Focus Document Fiscal Year Focus Health Insurance Costs Health Insurance Costs [Policy Text Block] Disclosure of accounting policy for health insurance coverage to worksite employees. Right-of-use (“ROU”) leased assets Operating Lease, Right-of-Use Asset Entity Interactive Data Current Entity Interactive Data Current Other Balance Sheet Disclosures [Text Block] OtherBalanceSheetDisclosures [Text Block] The entire disclosure for other balance sheet components. Balance (shares) Balance (shares) Shares, Issued Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Amendment Flag Amendment Flag Central [Member] Central [Member] Central [Member] Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Segment Reporting Disclosure Segment Reporting Disclosure [Text Block] US Government Securities, at Carrying Value US Government Securities, at Carrying Value Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation 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] US Treasury Securities [Member] US Treasury Securities [Member] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Weighted average common shares outstanding basic (in shares) Weighted Average Number of Shares Outstanding, Basic Restricted cash Restricted Cash and Cash Equivalent, Current Summary of the net income allocated to common shares and the basic and diluted shares used in the net income per share computations Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Deferred income taxes, net Deferred Income Tax Assets, Net Exchange [Domain] Exchange [Domain] Segment Reporting [Abstract] Segment Reporting [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Other assets Other Assets, Noncurrent Entity Central Index Key Entity Central Index Key Debt Disclosure [Abstract] Debt Disclosure [Abstract] Other income (expense): Nonoperating Income (Expense) [Abstract] Entity Tax Identification Number Entity Tax Identification Number Supplemental cash flow information: Supplemental Cash Flow Elements [Abstract] Other Revenues [Member] Other Revenues [Member] Other Revenues [Member] Revenue Composition [Abstract] Revenue Composition [Abstract] Revenue Composition [Abstract] Revenues are comprised of gross billings less worksite ("WSEE") payroll costs Salaries, wages and payroll taxes Salaries, wages and payroll taxes The aggregate amount of expenditures for salaries, wages, and payroll taxes of corporate and sales staff. Income taxes receivable Income Taxes Receivable, Current Quarterly dividends declared [Table Text Block] Quarterly dividends declared [Table Text Block] Quarterly dividends declared [Table Text Block] - tabular disclosure of all or some of the information related to dividends declared and paid as of the financial reporting date. Entity Filer Category Entity Filer Category Local Phone Number Local Phone Number Required deposit equal to approximately one day of claims funding activity Required deposit for health care costs Represents the amount required to be held on deposit with United, which is determined as approximately one day of claims funding activity. Workers' Compensation Costs Workers' Compensation Costs [Policy Text Block] Disclosure of accounting policy for accruing workers' compensation insurance expense. Assets Assets [Abstract] Long-term debt Long-Term Debt, Excluding Current Maturities Credit Facility [Axis] Credit Facility [Axis] Security Exchange Name Security Exchange Name Fair Value Disclosures [Text Block] Fair Value Disclosures [Text Block] Credit Facility [Domain] Credit Facility [Domain] Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Equity, Attributable to Parent [Abstract] Total noncurrent liabilities Liabilities, Noncurrent Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Entity Address, Address Line One Entity Address, Address Line One Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Treasury Stock, Value, Acquired, Cost Method Treasury Stock, Value, Acquired, Cost Method Number of days in advance of the beginning of a reporting quarter United establishes cash funding rates Number of days in advance of the beginning of a reporting quarter carrier establishes cash funding rates The number of days in advance of the beginning of a reporting quarter that United Healthcare establishes cash funding rates. Shares withheld for tax withholding obligations for the vesting of restricted stock awards (in shares) Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Operating lease liabilities, net of current Operating Lease, Liability, Noncurrent Line of Credit Facility, Interest Rate During Period Line of Credit Facility, Interest Rate During Period Statement [Line Items] Statement [Line Items] Entity Registrant Name Entity Registrant Name Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalent Other assets and ROU assets Increase (Decrease) in Other Noncurrent Assets Common Stock [Member] Common Stock [Member] Common Stock [Member] Debt Securities, Available-for-sale Debt Securities, Available-for-Sale Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Fair Value, Inputs, Level 1, Level 2, and Level 3 Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Premiums owed to United Premiums owed to United The premiums owed to United which is included in accrued health insurance costs, a current liability in the Company's Consolidated Balance Sheet. Total adjustments Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements