Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Details) (USD $)	3 Months Ended
	Mar. 31, 2012
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	$ 21,300,000
Goodwill, Beginning Balance	1,237,607,000
Goodwill acquired	102,347,000
Other	(1,385,000)
Goodwill, Ending Balance	1,338,569,000
Goodwill, Impairment Loss	0
Animal Hospital [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	1,035,401,000
Goodwill acquired	92,264,000
Other	(1,565,000)
Goodwill, Ending Balance	1,126,100,000
Laboratory [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	96,810,000
Goodwill acquired	8,000
Other	13,000
Goodwill, Ending Balance	96,831,000
All Other [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	105,396,000
Goodwill acquired	10,075,000
Other	167,000
Goodwill, Ending Balance	$ 115,638,000