Segment Information - Reconciliation of Adjusted EBITDA to Income Before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment information
Adjusted EBITDA	$ 807,425	$ 646,863	$ 947,359
Depreciation and amortization	(208,742)	(205,825)	(202,645)
Stock compensation expense	(43,809)	(37,755)	(30,940)
Income from operations	554,874	403,283	713,774
Loss on early retirement of debt	(14,692)	0	0
Equity in earnings of unconsolidated subsidiaries	40,813	26,407	44,428
Gain on sale of businesses	0	0	2,155
Interest income	0	0	5,350
Interest expense	(198,639)	(169,111)	(135,985)
Income before income taxes	382,356	260,579	629,722
Operating Segments | Critical Illness Recovery Hospital
Segment information
Adjusted EBITDA	246,015	111,344	267,993
Depreciation and amortization	(63,865)	(61,565)	(53,094)
Stock compensation expense	0	0	0
Income from operations	182,150	49,779	214,899
Operating Segments | Rehabilitation Hospital
Segment information
Adjusted EBITDA	221,875	198,034	184,704
Depreciation and amortization	(28,055)	(27,814)	(27,677)
Stock compensation expense	0	0	0
Income from operations	193,820	170,220	157,027
Operating Segments | Outpatient Rehabilitation
Segment information
Adjusted EBITDA	111,868	101,860	138,275
Depreciation and amortization	(35,210)	(32,663)	(29,592)
Stock compensation expense	0	0	0
Income from operations	76,658	69,197	108,683
Operating Segments | Concentra
Segment information
Adjusted EBITDA	361,334	334,337	389,616
Depreciation and amortization	(73,051)	(73,667)	(82,210)
Stock compensation expense	(651)	(2,141)	(2,142)
Income from operations	287,632	258,529	305,264
Corporate, non-Segment
Segment information
Adjusted EBITDA	(133,667)	(98,712)	(33,229)
Depreciation and amortization	(8,561)	(10,116)	(10,072)
Stock compensation expense	(43,158)	(35,614)	(28,798)
Income from operations	$ (185,386)	$ (144,442)	$ (72,099)