Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Goodwill [Line Items]
Future Amortization Expense, Remainder of Fiscal Year	$ 15,367,000
Finite-Lived Intangible Assets, Amortization Expense	5,044,000	4,876,000
Finite-Lived Intangible Assets, Gross	145,866,000	150,427,000
Goodwill, Impaired, Accumulated Impairment Loss	(120,811,000)		(120,811,000)
Goodwill, Gross	1,415,000,000		1,412,042,000
Goodwill, Beginning Balance	1,291,231,000
Goodwill acquired	4,972,000
Goodwill, Translation Adjustments	(2,049,000)
Other	35,000
Goodwill, Ending Balance	1,294,189,000
Finite-Lived Intangible Assets, Accumulated Amortization	(55,471,000)	(55,604,000)
Finite-Lived Intangible Assets, Net	90,395,000	94,823,000	94,823,000
Future Amortization Expense, Year One	18,500,000
Future Amortization Expense, Year Two	16,462,000
Future Amortization Expense, Year Three	13,416,000
Future Amortization Expense, Year Four	6,867,000
Future Amortization Expense, after Year Five	19,783,000
Animal Hospital [Member]
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	0		0
Goodwill, Gross	1,179,882,000		1,177,348,000
Goodwill, Beginning Balance	1,177,348,000
Goodwill acquired	4,957,000
Goodwill, Translation Adjustments	(2,034,000)
Other	(389,000)
Goodwill, Ending Balance	1,179,882,000
All Other Segments [Member]
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	(120,811,000)		(120,811,000)
Goodwill, Beginning Balance			17,022,000
Goodwill, Ending Balance	17,446,000		17,022,000
Laboratory [Member]
Goodwill [Line Items]
Goodwill, Impaired, Accumulated Impairment Loss	0		0
Goodwill, Gross	96,861,000		96,861,000
Goodwill, Beginning Balance	96,861,000
Goodwill acquired	15,000
Goodwill, Translation Adjustments	(15,000)
Other	0
Goodwill, Ending Balance	96,861,000
All Other [Member]
Goodwill [Line Items]
Goodwill, Gross	138,257,000		137,833,000
Goodwill acquired	0
Goodwill, Translation Adjustments	0
Other	424,000
Customer Lists [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	50,000	50,000
Finite-Lived Intangible Assets, Accumulated Amortization	(30,000)	(26,000)
Finite-Lived Intangible Assets, Net	20,000	24,000
Contract [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	956,000	956,000
Finite-Lived Intangible Assets, Accumulated Amortization	(591,000)	(570,000)
Finite-Lived Intangible Assets, Net	365,000	386,000
Trademarks [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	12,296,000	12,494,000
Finite-Lived Intangible Assets, Accumulated Amortization	(3,290,000)	(3,001,000)
Finite-Lived Intangible Assets, Net	9,006,000	9,493,000
Lease Agreements [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	7,228,000	7,228,000
Finite-Lived Intangible Assets, Accumulated Amortization	(3,999,000)	(3,866,000)
Finite-Lived Intangible Assets, Net	3,229,000	3,362,000
Noncompete Agreements [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	11,703,000	12,707,000
Finite-Lived Intangible Assets, Accumulated Amortization	(6,782,000)	(7,357,000)
Finite-Lived Intangible Assets, Net	4,921,000	5,350,000
Developed Technology Rights [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	6,588,000	6,588,000
Finite-Lived Intangible Assets, Accumulated Amortization	(4,312,000)	(4,179,000)
Finite-Lived Intangible Assets, Net	2,276,000	2,409,000
Customer Relationships [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	107,045,000	110,404,000
Finite-Lived Intangible Assets, Accumulated Amortization	(36,467,000)	(36,605,000)
Finite-Lived Intangible Assets, Net	$ 70,578,000	$ 73,799,000