Goodwill and Other Intangible Assets (Details 1) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period	$ 4,972,000
Other Intangible Assets
Gross Carrying Amount	145,866,000	150,427,000
Accumulated Amortization	(55,471,000)	(55,604,000)
Total	90,395,000	94,823,000	94,823,000
Aggregate amortization expense	5,044,000	4,876,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2012	15,367,000
2013	18,500,000
2014	16,462,000
2015	13,416,000
2016	6,867,000
Thereafter	19,783,000
Total	90,395,000	94,823,000	94,823,000
Goodwill and Other Intangible Assets (Textuals) [Abstract]
Accumulated impairment losses	(120,811,000)		(120,811,000)
Noncontractual customer relationships [Member]
Other Intangible Assets
Gross Carrying Amount	107,045,000	110,404,000
Accumulated Amortization	(36,467,000)	(36,605,000)
Total	70,578,000	73,799,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	70,578,000	73,799,000
Covenants not-to-compete [Member]
Other Intangible Assets
Gross Carrying Amount	11,703,000	12,707,000
Accumulated Amortization	(6,782,000)	(7,357,000)
Total	4,921,000	5,350,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	4,921,000	5,350,000
Favorable lease asset [Member]
Other Intangible Assets
Gross Carrying Amount	7,228,000	7,228,000
Accumulated Amortization	(3,999,000)	(3,866,000)
Total	3,229,000	3,362,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	3,229,000	3,362,000
Trademarks [Member]
Other Intangible Assets
Gross Carrying Amount	12,296,000	12,494,000
Accumulated Amortization	(3,290,000)	(3,001,000)
Total	9,006,000	9,493,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	9,006,000	9,493,000
Contracts [Member]
Other Intangible Assets
Gross Carrying Amount	956,000	956,000
Accumulated Amortization	(591,000)	(570,000)
Total	365,000	386,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	365,000	386,000
Technology [Member]
Other Intangible Assets
Gross Carrying Amount	6,588,000	6,588,000
Accumulated Amortization	(4,312,000)	(4,179,000)
Total	2,276,000	2,409,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	2,276,000	2,409,000
Client lists [Member]
Other Intangible Assets
Gross Carrying Amount	50,000	50,000
Accumulated Amortization	(30,000)	(26,000)
Total	20,000	24,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Total	20,000	24,000
Laboratory [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period	15,000
Goodwill and Other Intangible Assets (Textuals) [Abstract]
Accumulated impairment losses	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	4,957,000
Goodwill and Other Intangible Assets (Textuals) [Abstract]
Accumulated impairment losses	$ 0		$ 0