Acquisition (Details) (USD $)	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Consideration:
Cash	$ 17,295,000		$ 6,756,000
Contingent consideration	1,900,000				2,200,000
Allocation of the Purchase Price:
Goodwill	1,340,054,000				1,330,917,000
Noncontrolling interest	(855,000)		0
Cash payments for real estate	0		510,000
Animal Hospital [Member]
Business Acquisition Summary Of Acquired Properties [Line Items]
Acquisitions	(4)		(3)
Acquisitions, merged	(1)		0
Sold, closed or merged	(4)		(8)
Net decrease in Animal Hospitals	(1)		(5)
Consideration:
Cash	17,295,000		6,756,000
Holdbacks	400,000		160,000
Contingent consideration	0		53,000
Fair value of total consideration transferred	17,695,000		6,969,000
Allocation of the Purchase Price:
Tangible assets	701,000		491,000
Identifiable intangible assets	2,734,000		1,506,000
Goodwill	15,115,000	[1]	4,972,000	[1]
Fair value of assets acquired	18,550,000		6,969,000
Noncontrolling interest	(855,000)		0
Total	17,695,000		6,969,000
Goodwill recorded for acquisitions, fully deductible for income tax purposes	$ 10,300,000		$ 4,100,000
Laboratories Acquisitions [Member]
Business Acquisition Summary Of Acquired Properties [Line Items]
Acquisitions	0		(1)
Created	1		0
Net increase in Laboratories	1		1

[1] We expect that $10.3 million and $4.1 million of the goodwill recorded for these acquisitions, as of March 31, 2014 and 2013, respectively, will be fully deductible for income tax purposes.