Accounting Policies	9 Months Ended
Accounting Policies	Sep. 30, 2019
Accounting Policies [Abstract]
Accounting Policies	Accounting Policies 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 and liabilities, including disclosure of contingencies, at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Credit Risk Concentrations Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash balances and trade receivables. 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. The Company’s general policy is to verify insurance coverage prior to the date of admission for patients admitted to the Company’s critical illness recovery hospitals and rehabilitation hospitals. Within the Company’s outpatient rehabilitation clinics, the Company verifies insurance coverage prior to the patient’s visit. Within the Company’s Concentra centers, the Company verifies insurance coverage or receives authorization from the patient’s employer prior to the patient’s visit. Because of the geographic diversity of the Company’s facilities and non-governmental third-party payors, Medicare represents the Company’s only significant concentration of credit risk. Approximately 16% and 15% of the Company’s accounts receivable is from Medicare at December 31, 2018, and September 30, 2019, respectively. Leases The Company evaluates whether a contract is or contains a lease at the inception of the contract. Upon lease commencement, the date on which a lessor makes the underlying asset available to the Company for use, the Company classifies the lease as either an operating or finance lease. Most of the Company’s facility and equipment leases are classified as operating leases. Balance Sheet For both operating and finance leases, the Company recognizes a right-of-use asset and lease liability at lease commencement. A right-of-use asset represents the Company’s right to use an underlying asset for the lease term while the lease liability represents an obligation to make lease payments arising from a lease which are measured on a discounted basis. The Company elected the short-term lease exemption for its equipment leases; accordingly, equipment leases with an initial term of 12 months or less are not recorded on the consolidated balance sheets. Lease liabilities are measured at the present value of the remaining, fixed lease payments at lease commencement. The Company primarily uses its incremental borrowing rate, based on the information available at lease commencement, in determining the present value of its remaining lease payments. The Company’s leases may also specify extension or termination clauses. These options are factored into the measurement of the lease liability when it is reasonably certain that the Company will exercise the option. Right-of-use assets are measured at an amount equal to the initial lease liability, plus any prepaid lease payments (less any incentives received, such as reimbursement for leasehold improvements) and initial direct costs, at the lease commencement date. The Company has elected to account for lease and non-lease components, such as common area maintenance, as a single lease component for its facility leases. As a result, the fixed payments that would otherwise be allocated to the non-lease components will be accounted for as lease payments and are included in the measurement of the Company’s right-of-use asset and lease liability. Statement of Operations For the Company’s operating leases, rent expense, a component of cost of services and general and administrative expenses on the consolidated statements of operations, is recognized on a straight-line basis over the lease term. The straight-line rent expense is reflective of the interest expense on the lease liability using the effective interest method and the amortization of the right-of-use asset. The Company may enter into arrangements to sublease portions of its facilities and the Company typically retains the obligation to the lessor under these arrangements. The Company’s subleases are classified as operating leases; accordingly, the Company continues to account for the original leases as it did prior to commencement of the subleases. Sublease income, a component of cost of services on the consolidated statements of operations, is recognized on a straight-line basis, as a reduction to rent expense, over the term of the sublease. For the Company’s finance leases, interest expense on the lease liability is recognized using the effective interest method. Amortization expense related to the right-of-use asset is recognized on a straight-line basis over the shorter of the estimated useful life of the asset or the lease term. The Company elected the short-term lease exemption for its equipment leases. For these leases, the Company recognizes lease payments on a straight-line basis over the lease term and variable lease payments are expensed as incurred. These expenses are included as components of cost of services on the consolidated statements of operations. The Company makes payments related to changes in indexes or rates after the lease commencement date. Additionally, the Company makes payments, which are not fixed at lease commencement, for property taxes, insurance, and common area maintenance related to its facility leases. These variable lease payments, which are expensed as incurred, are included as a component of cost of services and general and administrative expenses on the consolidated statements of operations. Recent Accounting Pronouncements Financial Instruments In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments — Credit Losses: Measurement of Credit Losses on Financial Instruments. The current standard delays the recognition of a credit loss on a financial asset until the loss is probable of occurring. The new standard removes the requirement that a credit loss be probable of occurring for it to be recognized and requires entities to use historical experience, current conditions, and reasonable and supportable forecasts to estimate their future expected credit losses. The financial instruments subject to ASU 2016-13 are the Company’s accounts receivable and notes receivable. The standard will be effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The guidance must be applied using a modified retrospective approach through a cumulative-effect adjustment to retained earnings as of the beginning of the earliest comparative period in the financial statements. Given the very high rate of collectability of the Company’s financial instruments, the impact of ASU 2016-13 will not be material to the Company’s consolidated financial statements. The Company’s implementation efforts are focused on finalizing the accounting processes and related controls associated with accounting for its financial instruments under the new standard. Recently Adopted Accounting Pronouncements Leases The Company adopted Accounting Standards Codification (“ASC”) Topic 842, Leases using a modified retrospective approach as of January 1, 2019, for leases which existed on that date. Prior comparative periods were not adjusted and continue to be reported in accordance with ASC Topic 840, Leases. The Company elected the package of practical expedients, which permitted the Company not to reassess under ASC Topic 842 the Company’s prior conclusions about lease identification, lease classification, and initial direct costs. The Company did not elect the use-of-hindsight or the practical expedient pertaining to land easements; the latter not being applicable to the Company. The adoption of the standard resulted in the recognition of operating lease right-of-use assets of $1,015.0 million and operating lease liabilities of $1,057.0 million at January 1, 2019. The difference between the operating lease right-of-use assets and operating lease liabilities resulted from the reclassification of prepaid rent, deferred rent, unamortized lease incentives, and acquired favorable and unfavorable leasehold interests upon adoption. The Company did not recognize a cumulative-effect adjustment to retained earnings upon adoption.