Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Details) (USD $)	9 Months Ended
	Sep. 30, 2012
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	$ 21,300,000
Goodwill, Beginning Balance	1,237,607,000
Goodwill acquired	131,733,000
Goodwill, Translation Adjustments	2,076,000
Other	(5,299,000)
Goodwill, Ending Balance	1,366,117,000
Goodwill, Impairment Loss	0
Animal Hospital [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	1,035,401,000
Goodwill acquired	120,505,000
Goodwill, Translation Adjustments	2,053,000
Other	(4,271,000)
Goodwill, Ending Balance	1,153,688,000
Laboratory [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	96,810,000
Goodwill acquired	34,000
Goodwill, Translation Adjustments	23,000
Other	0
Goodwill, Ending Balance	96,867,000
All Other [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	105,396,000
Goodwill acquired	11,194,000
Goodwill, Translation Adjustments	0
Other	(1,028,000)
Goodwill, Ending Balance	$ 115,562,000