Goodwill and Other Intangible Assets (Details 1) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Remainder of 2012			$ 6,040,000
2013			22,377,000
2014			19,935,000
2015			17,837,000
2016			14,586,000
Thereafter			35,987,000
Total			116,762,000
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			131,733,000
Other Intangible Assets
Gross Carrying Amount	167,877,000		167,877,000		129,075,000
Accumulated Amortization	(51,115,000)		(51,115,000)		(36,672,000)
Net Carrying Amount	116,762,000		116,762,000		92,403,000
Aggregate amortization expense	6,612,000	3,883,000	16,830,000	9,092,000
Goodwill and Other Intangible Assets (Textuals) [Abstract]
Accumulated impairment losses	21,300,000		21,300,000
Noncontractual customer relationships [Member]
Other Intangible Assets
Gross Carrying Amount	113,689,000		113,689,000		82,891,000
Accumulated Amortization	(33,011,000)		(33,011,000)		(21,147,000)
Net Carrying Amount	80,678,000		80,678,000		61,744,000
Covenants not-to-compete [Member]
Other Intangible Assets
Gross Carrying Amount	12,262,000		12,262,000		13,035,000
Accumulated Amortization	(7,225,000)		(7,225,000)		(8,067,000)
Net Carrying Amount	5,037,000		5,037,000		4,968,000
Favorable lease asset [Member]
Other Intangible Assets
Gross Carrying Amount	7,163,000		7,163,000		5,571,000
Accumulated Amortization	(3,717,000)		(3,717,000)		(3,210,000)
Net Carrying Amount	3,446,000		3,446,000		2,361,000
Trademarks [Member]
Other Intangible Assets
Gross Carrying Amount	14,017,000		14,017,000		7,405,000
Accumulated Amortization	(2,667,000)		(2,667,000)		(1,686,000)
Net Carrying Amount	11,350,000		11,350,000		5,719,000
Contracts [Member]
Other Intangible Assets
Gross Carrying Amount	3,500,000		3,500,000		3,500,000
Accumulated Amortization	(519,000)		(519,000)		(185,000)
Net Carrying Amount	2,981,000		2,981,000		3,315,000
Technology [Member]
Other Intangible Assets
Gross Carrying Amount	17,161,000		17,161,000		16,589,000
Accumulated Amortization	(3,919,000)		(3,919,000)		(2,342,000)
Net Carrying Amount	13,242,000		13,242,000		14,247,000
Client lists [Member]
Other Intangible Assets
Gross Carrying Amount	85,000		85,000		84,000
Accumulated Amortization	(57,000)		(57,000)		(35,000)
Net Carrying Amount	28,000		28,000		49,000
Laboratory [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			34,000
All Other [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			11,194,000
Animal Hospital [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			$ 120,505,000