Segment Information - Selected Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment information
Net operating revenues	$ 1,414,632	$ 1,324,631
Adjusted EBITDA	187,333	170,117
Total assets	7,115,567	7,021,492	$ 7,340,288
Purchases of property and equipment, net	39,208	49,073
Operating Segments | Critical Illness Recovery Hospital
Segment information
Net operating revenues	500,521	457,534
Adjusted EBITDA	88,570	72,998
Total assets	2,148,779	2,062,659
Purchases of property and equipment, net	8,965	10,160
Operating Segments | Rehabilitation Hospital
Segment information
Net operating revenues	182,019	154,558
Adjusted EBITDA	38,569	25,797
Total assets	1,127,267	1,089,391
Purchases of property and equipment, net	3,325	13,183
Operating Segments | Outpatient Rehabilitation
Segment information
Net operating revenues	255,249	246,905
Adjusted EBITDA	27,122	28,991
Total assets	1,285,449	1,250,015
Purchases of property and equipment, net	8,384	9,040
Operating Segments | Concentra
Segment information
Net operating revenues	398,535	396,321
Adjusted EBITDA	61,466	66,258
Total assets	2,354,169	2,464,317
Purchases of property and equipment, net	15,586	15,698
Other
Segment information
Net operating revenues	78,308	69,313
Adjusted EBITDA	(28,394)	(23,927)
Total assets	199,903	155,110
Purchases of property and equipment, net	$ 2,948	$ 992