Long-Term Debt and Notes Payable - Components of Long-Term Debt And Notes Payable (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Principal Outstanding	$ 3,353,091	$ 3,338,381
Unamortized Premium (Discount)	(11,329)	(11,905)
Unamortized Issuance Costs	(30,330)	(33,095)
Carrying Value	3,311,432	3,293,381
Fair Value	3,328,406	3,222,705
Select Medical Corporation
Debt Instrument [Line Items]
Principal Outstanding	1,965,876	1,916,290
Unamortized Premium (Discount)	(8,774)	(9,140)
Unamortized Issuance Costs	(13,453)	(14,447)
Carrying Value	1,943,649	1,892,703
Fair Value	$ 1,947,943	1,856,987
Select Medical Corporation \| Senior notes \| 6.375% Senior Notes Due June 2021
Debt Instrument [Line Items]
Interest rate of debt (as a percent)	6.375%
Principal Outstanding	$ 710,000	710,000
Unamortized Premium (Discount)	493	550
Unamortized Issuance Costs	(4,162)	(4,642)
Carrying Value	706,331	705,908
Fair Value	711,775	706,450
Select Medical Corporation \| Other debt, including finance leases
Debt Instrument [Line Items]
Principal Outstanding	64,808	56,415
Unamortized Premium (Discount)	0	0
Unamortized Issuance Costs	(464)	(484)
Carrying Value	64,344	55,931
Fair Value	64,344	55,931
Select Medical Corporation \| Revolving facility \| Credit facilities
Debt Instrument [Line Items]
Principal Outstanding	160,000	20,000
Unamortized Premium (Discount)	0	0
Unamortized Issuance Costs	0	0
Carrying Value	160,000	20,000
Fair Value	147,200	18,400
Select Medical Corporation \| Term loans \| Credit facilities
Debt Instrument [Line Items]
Principal Outstanding	1,031,068	1,129,875
Unamortized Premium (Discount)	(9,267)	(9,690)
Unamortized Issuance Costs	(8,827)	(9,321)
Carrying Value	1,012,974	1,110,864
Fair Value	1,024,624	1,076,206
Concentra Inc
Debt Instrument [Line Items]
Principal Outstanding	1,387,215	1,422,091
Unamortized Premium (Discount)	(2,555)	(2,765)
Unamortized Issuance Costs	(16,877)	(18,648)
Carrying Value	1,367,783	1,400,678
Fair Value	1,380,463	1,365,718
Concentra Inc \| Other debt, including finance leases
Debt Instrument [Line Items]
Principal Outstanding	6,918	7,916
Unamortized Premium (Discount)	0	0
Unamortized Issuance Costs	0	0
Carrying Value	6,918	7,916
Fair Value	6,918	7,916
Concentra Inc \| Term loans \| Credit facilities
Debt Instrument [Line Items]
Principal Outstanding	1,380,297	1,414,175
Unamortized Premium (Discount)	(2,555)	(2,765)
Unamortized Issuance Costs	(16,877)	(18,648)
Carrying Value	1,360,865	1,392,762
Fair Value	$ 1,373,545	$ 1,357,802

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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