Acquisition (Details) (USD $)	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Dec. 31, 2013
Consideration:
Cash	$ 29,271,000		$ 21,835,000
Earnout contingent consideration	1,600,000				2,200,000
Allocation of the Purchase Price:
Goodwill	1,355,396,000				1,330,917,000
Cash payments for real estate	1,493,000		510,000
Animal Hospital [Member]
Business Acquisition Summary Of Acquired Properties [Line Items]
Acquisitions	10		6
Acquisitions, merged	(2)		(1)
Sold, closed or merged	(5)		(9)
Net increase (decrease) in Animal Hospitals	3		(4)
Consideration:
Cash	29,271,000		21,835,000
Assumed debt	736,000		0
Holdbacks	750,000		460,000
Earnout contingent consideration	374,000		46,000
Fair value of total consideration transferred	31,131,000		22,341,000
Allocation of the Purchase Price:
Tangible assets	1,195,000		2,548,000
Identifiable intangible assets	4,880,000		2,946,000
Goodwill	26,761,000	[1]	20,979,000	[1]
Other liabilities assumed	0		(532,000)
Fair value of assets acquired	32,836,000		25,941,000
Noncontrolling interest	(1,705,000)		(3,600,000)
Total	31,131,000		22,341,000
Goodwill recorded for acquisitions, fully deductible for income tax purposes	$ 16,300,000		$ 20,200,000
Laboratories Acquisitions [Member]
Business Acquisition Summary Of Acquired Properties [Line Items]
Acquisitions	0		1
Created	3		0
Net increase in Laboratories	3		1

[1] We expect that $16.3 million and $20.2 million of the goodwill recorded for these acquisitions, as of June 30, 2014 and 2013, respectively, will be fully deductible for income tax purposes.