Segment Information - Reconciliation of Adjusted EBITDA to Income Before Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 163,847	$ 258,341
Depreciation and amortization	(51,039)	(49,620)
Income from operations	103,985	202,012
Equity in earnings of unconsolidated subsidiaries	5,397	9,919
Interest income	0	4,749
Interest expense	(35,514)	(34,402)
Income before income taxes	73,868	182,278
Operating Segments | Critical Illness Recovery Hospital
Segment Reporting Information [Line Items]
Adjusted EBITDA	35,967	113,272
Depreciation and amortization	(14,618)	(13,050)
Stock compensation expense	0	0
Income from operations	21,349	100,222
Operating Segments | Rehabilitation Hospital
Segment Reporting Information [Line Items]
Adjusted EBITDA	42,379	50,534
Depreciation and amortization	(6,802)	(7,060)
Stock compensation expense	0	0
Income from operations	35,577	43,474
Operating Segments | Outpatient Rehabilitation
Segment Reporting Information [Line Items]
Adjusted EBITDA	26,596	26,329
Depreciation and amortization	(8,029)	(7,191)
Stock compensation expense	0	0
Income from operations	18,567	19,138
Operating Segments | Concentra
Segment Reporting Information [Line Items]
Adjusted EBITDA	89,469	82,015
Depreciation and amortization	(18,812)	(19,898)
Stock compensation expense	(535)	(536)
Income from operations	70,122	61,581
Other
Segment Reporting Information [Line Items]
Adjusted EBITDA	(30,564)	(13,809)
Depreciation and amortization	(2,778)	(2,421)
Stock compensation expense	(8,288)	(6,173)
Income from operations	$ (41,630)	$ (22,403)