Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Critical Illness Recovery Hospital
Disaggregation of Revenue [Line Items]
Total net operating revenues	$ 442,452	$ 439,194	$ 907,128	$ 884,317
Critical Illness Recovery Hospital | Patient services revenue
Disaggregation of Revenue [Line Items]
Total net operating revenues	438,940	436,608	899,938	879,670
Critical Illness Recovery Hospital | Medicare
Disaggregation of Revenue [Line Items]
Total net operating revenues	225,857	228,733	466,849	465,170
Critical Illness Recovery Hospital | Non-Medicare
Disaggregation of Revenue [Line Items]
Total net operating revenues	213,083	207,875	433,089	414,500
Critical Illness Recovery Hospital | Other revenues
Disaggregation of Revenue [Line Items]
Total net operating revenues	3,512	2,586	7,190	4,647
Rehabilitation Hospital
Disaggregation of Revenue [Line Items]
Total net operating revenues	173,769	151,378	348,543	296,203
Rehabilitation Hospital | Patient services revenue
Disaggregation of Revenue [Line Items]
Total net operating revenues	135,441	113,523	270,184	218,270
Rehabilitation Hospital | Medicare
Disaggregation of Revenue [Line Items]
Total net operating revenues	73,054	62,089	145,895	119,593
Rehabilitation Hospital | Non-Medicare
Disaggregation of Revenue [Line Items]
Total net operating revenues	62,387	51,434	124,289	98,677
Rehabilitation Hospital | Other revenues
Disaggregation of Revenue [Line Items]
Total net operating revenues	38,328	37,855	78,359	77,933
Outpatient Rehabilitation
Disaggregation of Revenue [Line Items]
Total net operating revenues	267,183	254,984	524,564	505,355
Outpatient Rehabilitation | Patient services revenue
Disaggregation of Revenue [Line Items]
Total net operating revenues	236,086	227,128	463,176	447,629
Outpatient Rehabilitation | Medicare
Disaggregation of Revenue [Line Items]
Total net operating revenues	41,475	38,119	79,665	74,817
Outpatient Rehabilitation | Non-Medicare
Disaggregation of Revenue [Line Items]
Total net operating revenues	194,611	189,009	383,511	372,812
Outpatient Rehabilitation | Other revenues
Disaggregation of Revenue [Line Items]
Total net operating revenues	31,097	27,856	61,388	57,726
Concentra
Disaggregation of Revenue [Line Items]
Total net operating revenues	412,823	256,887	768,939	507,476
Concentra | Patient services revenue
Disaggregation of Revenue [Line Items]
Total net operating revenues	410,439	254,678	764,319	503,024
Concentra | Medicare
Disaggregation of Revenue [Line Items]
Total net operating revenues	517	571	1,145	1,116
Concentra | Non-Medicare
Disaggregation of Revenue [Line Items]
Total net operating revenues	409,922	254,107	763,174	501,908
Concentra | Other revenues
Disaggregation of Revenue [Line Items]
Total net operating revenues	$ 2,384	$ 2,209	$ 4,620	$ 4,452