Acquisitions - Narrative (Details) - USD ($) $ in Thousands		2 Months Ended	3 Months Ended
	Feb. 01, 2018	Mar. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Acquisitions
Non-cash equity exchange for acquisition of U.S. HealthWorks		$ 238,000	$ 238,000		$ 0
Consideration given and net cash paid for identifiable net assets and goodwill acquired
Goodwill		3,318,611	3,318,611	$ 2,782,812
U.S. HealthWorks
Acquisitions
U.S. HealthWorks acquisition costs			$ 2,900
Total consideration (net of cash acquired)	$ 753,000
Estimated value of goodwill, deductible for tax purposes	83,100
Net revenues of acquiree		$ 89,900
Consideration given and net cash paid for identifiable net assets and goodwill acquired
Identifiable tangible assets	184,357
Identifiable intangible assets	105,000
Goodwill	535,595
Total assets	824,952
Total liabilities	71,952
Consideration given	$ 753,000
Concentra Group Holdings Parent, LLC | U.S. HealthWorks
Acquisitions
Equity interest issued (percent)	20.00%
Non-cash equity exchange for acquisition of U.S. HealthWorks	$ 238,000