Long-Term Debt and Notes Payable - Components of Long-Term Debt And Notes Payable (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Principal Outstanding	$ 3,402,394	$ 3,403,043
Unamortized Premium (Discount)	22,285	25,380
Unamortized Issuance Costs	(22,456)	(26,404)
Carrying Value	3,402,223	3,402,019
Fair Value	3,446,530	3,473,582
Other debt, including finance leases
Debt Instrument [Line Items]
Principal Outstanding	73,957	74,606
Unamortized Premium (Discount)	0	0
Unamortized Issuance Costs	(236)	(302)
Carrying Value	73,721	74,304
Fair Value	$ 73,721	$ 74,304
Select Medical Corporation \| Senior notes
Debt Instrument [Line Items]
Interest rate of debt (as a percent)	6.25%	6.25%
Principal Outstanding	$ 1,225,000	$ 1,225,000
Unamortized Premium (Discount)	29,177	33,773
Unamortized Issuance Costs	(14,707)	(16,953)
Carrying Value	1,239,470	1,241,820
Fair Value	1,285,148	1,316,875
Select Medical Corporation \| Term loans
Debt Instrument [Line Items]
Principal Outstanding	2,103,437	2,103,437
Unamortized Premium (Discount)	(6,892)	(8,393)
Unamortized Issuance Costs	(7,513)	(9,149)
Carrying Value	2,089,032	2,085,895
Fair Value	$ 2,087,661	$ 2,082,403

Long-Term Debt And Finance Lease Obligation

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Long-Term Debt, Gross And Finance Lease Obligation

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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