Summary of Significant Accounting Policies (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Goodwill
Goodwill, Beginning Balance		$ 1,291,231	$ 1,237,607
Goodwill acquired		45,665	156,115
Goodwill impairment	(123,600)		(99,501)	(21,310)
Other		(288)	(4,288)
Goodwill, Ending Balance	1,291,231	1,330,917	1,291,231	1,237,607
Goodwill, Impaired, Accumulated Impairment Loss	120,811	(120,811)	120,811	21,310
Animal Hospital [Member]
Goodwill
Goodwill, Beginning Balance		1,177,348	1,035,401
Goodwill acquired		45,615	143,926
Goodwill impairment			0	0
Other		(731)	(3,260)
Goodwill, Ending Balance	1,177,348	1,216,581	1,177,348	1,035,401
Goodwill, Impaired, Accumulated Impairment Loss	0	0	0	0
Laboratory [Member]
Goodwill
Goodwill, Beginning Balance		96,861	96,810
Goodwill acquired		50	34
Goodwill impairment			0	0
Other		0	0
Goodwill, Ending Balance	96,861	96,871	96,861	96,810
Goodwill, Impaired, Accumulated Impairment Loss	0	0	0	0
All Other [Member]
Goodwill
Goodwill, Beginning Balance		17,022	105,396
Goodwill acquired		0	12,155
Goodwill impairment			(99,501)	(21,310)
Other		443	(1,028)
Goodwill, Ending Balance	17,022	17,465	17,022	105,396
Goodwill, Impaired, Accumulated Impairment Loss	$ 120,811	$ (120,811)	$ 120,811	$ 21,310