Segment Information - Selected Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Revenue	$ 1,674,528	$ 1,584,741	$ 3,339,508	$ 3,184,288
Adjusted EBITDA	219,469	180,994	433,532	344,841
Total assets	7,701,869	7,551,658	7,701,869	7,551,658	$ 7,665,293
Purchases of property, equipment, and other assets	59,514	46,332	118,399	93,177
Operating Segments | Critical Illness Recovery Hospital
Segment Reporting Information [Line Items]
Revenue	575,091	545,908	1,169,017	1,147,663
Adjusted EBITDA	65,496	20,019	142,269	55,986
Total assets	2,492,370	2,387,516	2,492,370	2,387,516
Purchases of property, equipment, and other assets	31,363	19,528	55,021	39,097
Operating Segments | Rehabilitation Hospital
Segment Reporting Information [Line Items]
Revenue	240,856	228,887	472,318	449,521
Adjusted EBITDA	54,689	49,845	101,905	92,224
Total assets	1,209,737	1,194,739	1,209,737	1,194,739
Purchases of property, equipment, and other assets	1,903	4,821	10,485	11,095
Operating Segments | Outpatient Rehabilitation
Segment Reporting Information [Line Items]
Revenue	302,972	287,258	598,875	559,198
Adjusted EBITDA	32,850	33,601	63,049	60,197
Total assets	1,399,782	1,360,600	1,399,782	1,360,600
Purchases of property, equipment, and other assets	10,476	9,314	20,408	18,728
Operating Segments | Concentra
Segment Reporting Information [Line Items]
Revenue	467,079	441,357	923,377	864,780
Adjusted EBITDA	100,391	92,607	194,139	182,076
Total assets	2,314,328	2,301,296	2,314,328	2,301,296
Purchases of property, equipment, and other assets	15,846	8,716	30,246	18,956
Other
Segment Reporting Information [Line Items]
Revenue	88,530	81,331	175,921	163,126
Adjusted EBITDA	(33,957)	(15,078)	(67,830)	(45,642)
Total assets	285,652	307,507	285,652	307,507
Purchases of property, equipment, and other assets	$ (74)	3,953	$ 2,239	5,301
Government assistance recognized in earnings, CARES Act		$ 15,100		$ 15,100