Accounting Policies (Policies)	9 Months Ended
Accounting Policies (Policies)	Sep. 30, 2021
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses. Actual results could differ from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Convertible Instruments and Contracts on an Entity’s Own Equity In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity. The ASU simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. As part of this update, convertible instruments are to be included in diluted earnings per share using the if-converted method, rather than the treasury stock method. Further, contracts which can be settled in cash or shares, excluding liability-classified share-based payment awards, are to be included in diluted earnings per share on an if-converted basis if the effect is dilutive, regardless of whether the entity or the counterparty can choose between cash and share settlement. The share-settlement presumption may not be rebutted based on past experience or a stated policy. This pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2021. The Company plans to adopt this pronouncement as of January 1, 2022. The use of either the modified retrospective or fully retrospective method of transition is permitted. Under the terms of the Amended and Restated Limited Liability Company Agreement of Concentra Group Holdings Parent, certain members of Concentra Group Holdings Parent have put rights that obligate the Company to purchase certain of such members’ equity interests in Concentra Group Holdings Parent when exercised. The Company can elect to pay the purchase price for those equity interests in cash or in shares of Holdings’ common stock. Under ASU 2020-06, the Company is no longer able to rebut the share-settlement presumption based on its past experience. Accordingly, if any of the put rights provided for under the Amended and Restated Limited Liability Company Agreement of Concentra Group Holdings Parent are outstanding upon adoption of ASU 2020-06, the shares which are potentially issuable will be included in diluted earnings per share, on an if-converted basis. At this time, the Company cannot reasonably estimate the impact that the adoption of ASU 2020-06 will have on its financial statements.
Credit Risk Concentrations	Credit Risk ConcentrationsFinancial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash balances and accounts receivable. The Company’s excess cash is held with large financial institutions. The Company grants unsecured credit to its patients, most of whom reside in the service area of the Company’s facilities and are insured under third-party payor agreements.Because of the diversity in the Company’s non-governmental third-party payor base, as well as their geographic dispersion, accounts receivable due from the Medicare program represent the Company’s only significant concentration of credit risk.
Redeemable Non-Controlling Interests	Redeemable Non-Controlling Interests The ownership interests held by outside parties in subsidiaries, which include limited liability companies and limited partnerships, controlled by the Company are classified as non-controlling interests. Some of the Company’s non-controlling ownership interests consist of outside parties that have certain redemption rights that, if exercised, require the Company to purchase the parties’ ownership interests. These interests are classified and reported as redeemable non-controlling interests and have been adjusted to their approximate redemption values, after the attribution of net income or loss. The Company’s redeemable non-controlling interests are comprised primarily of the voting membership interests owned by outside members of Concentra Group Holdings Parent, each of which have put rights with respect to their interests in Concentra Group Holdings Parent.
Variable Interest Entities	Variable Interest EntitiesCertain states prohibit the “corporate practice of medicine,” which restricts the Company from owning medical practices which directly employ physicians and from exercising control over medical decisions by physicians. In these states, the Company enters into long-term management agreements with medical practices that are owned by licensed physicians, which, in turn, employ or contract with physicians who provide professional medical services. The management agreements provide for the Company to direct the transfer of ownership of the medical practices to new licensed physicians at any time. Based on the provisions of the management agreements, the medical practices are variable interest entities for which the Company is the primary beneficiary.