Goodwill and Other Intangible Assets (Details 1) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			$ 32,557,000
Other Intangible Assets
Gross Carrying Amount	148,914,000	150,427,000	148,914,000	150,427,000
Accumulated Amortization	(58,775,000)	(55,604,000)	(58,775,000)	(55,604,000)
Total	90,139,000	94,823,000	90,139,000	94,823,000	94,823,000
Aggregate amortization expense	5,588,000	6,612,000	16,153,000	16,830,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2012	5,471,000		5,471,000
2013	20,613,000		20,613,000
2014	18,557,000		18,557,000
2015	15,520,000		15,520,000
2016	9,096,000		9,096,000
Thereafter	20,882,000		20,882,000
Total	90,139,000	94,823,000	90,139,000	94,823,000	94,823,000
Goodwill and Other Intangible Assets (Textuals) [Abstract]
Accumulated impairment losses	(120,811,000)		(120,811,000)		(120,811,000)
Noncontractual customer relationships [Member]
Other Intangible Assets
Gross Carrying Amount	113,573,000	110,404,000	113,573,000	110,404,000
Accumulated Amortization	(41,637,000)	(36,605,000)	(41,637,000)	(36,605,000)
Total	71,936,000	73,799,000	71,936,000	73,799,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	71,936,000	73,799,000	71,936,000	73,799,000
Covenants not-to-compete [Member]
Other Intangible Assets
Gross Carrying Amount	9,873,000	12,707,000	9,873,000	12,707,000
Accumulated Amortization	(5,458,000)	(7,357,000)	(5,458,000)	(7,357,000)
Total	4,415,000	5,350,000	4,415,000	5,350,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	4,415,000	5,350,000	4,415,000	5,350,000
Favorable lease asset [Member]
Other Intangible Assets
Gross Carrying Amount	7,465,000	7,228,000	7,465,000	7,228,000
Accumulated Amortization	(4,252,000)	(3,866,000)	(4,252,000)	(3,866,000)
Total	3,213,000	3,362,000	3,213,000	3,362,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	3,213,000	3,362,000	3,213,000	3,362,000
Trademarks [Member]
Other Intangible Assets
Gross Carrying Amount	12,096,000	12,494,000	12,096,000	12,494,000
Accumulated Amortization	(3,865,000)	(3,001,000)	(3,865,000)	(3,001,000)
Total	8,231,000	9,493,000	8,231,000	9,493,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	8,231,000	9,493,000	8,231,000	9,493,000
Contracts [Member]
Other Intangible Assets
Gross Carrying Amount	956,000	956,000	956,000	956,000
Accumulated Amortization	(633,000)	(570,000)	(633,000)	(570,000)
Total	323,000	386,000	323,000	386,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	323,000	386,000	323,000	386,000
Technology [Member]
Other Intangible Assets
Gross Carrying Amount	4,901,000	6,588,000	4,901,000	6,588,000
Accumulated Amortization	(2,891,000)	(4,179,000)	(2,891,000)	(4,179,000)
Total	2,010,000	2,409,000	2,010,000	2,409,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	2,010,000	2,409,000	2,010,000	2,409,000
Client lists [Member]
Other Intangible Assets
Gross Carrying Amount	50,000	50,000	50,000	50,000
Accumulated Amortization	(39,000)	(26,000)	(39,000)	(26,000)
Total	11,000	24,000	11,000	24,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	11,000	24,000	11,000	24,000
Laboratory [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			8,000
Goodwill and Other Intangible Assets (Textuals) [Abstract]
Accumulated impairment losses	0		0		0
All Other [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			0
Animal Hospital [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			32,549,000
Goodwill and Other Intangible Assets (Textuals) [Abstract]
Accumulated impairment losses	0		0		0
Animal Hospitals And Laboratory Acquisitions [Member]
Finite-Lived Intangible Assets [Line Items]
Business Acquisition, Purchase Price Allocation, Goodwill, Expected Tax Deductible Amount	$ 12,900,000	$ 40,000,000	$ 12,900,000	$ 40,000,000