Commitments and Contingencies - Litigation (Details) $ in Millions			3 Months Ended
	Oct. 19, 2015 hospital	Jul. 13, 2015 hospital	Mar. 31, 2018 USD ($)
Select, SSH-Knoxville, and SSH-North Knoxville
Commitments and Contingencies
Number of current or former employees named as defendants | hospital		10
Professional liability claims
Commitments and Contingencies
Self insurance retention limit			$ 35.0
Amended complaint | SSH-Evansville
Commitments and Contingencies
Number of case managers identified as plaintiff | hospital	2
Minimum | Joint Venture Operations | Professional liability claims
Commitments and Contingencies
Self insurance retention limit			5.0
Maximum | Joint Venture Operations | Professional liability claims
Commitments and Contingencies
Self insurance retention limit			$ 20.0