Acquisitions - Acquisition and Disposal Activity (Details)	6 Months Ended
	Jun. 30, 2016 Laboratory Hospital	Jun. 30, 2015 Laboratory Hospital
Animal Hospital
Business Acquisition Summary Of Acquired Properties [Line Items]
Acquisitions	93	23
Acquisitions, merged	(3)	(2)
Sold, closed or merged	(5)	(7)
Net increase	85	14
Laboratories Acquisitions
Business Acquisition Summary Of Acquired Properties [Line Items]
Acquisitions | Laboratory	0	1
Acquisitions, merged | Laboratory	0	(1)
Net increase | Laboratory	0	0