Acquisitions Acquisition (Details) (USD $)	9 Months Ended					3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Animal Hospital [Member] Hospital	Sep. 30, 2012 Animal Hospitals And Laboratory Acquisitions [Member]	Sep. 30, 2012 AVC [Member]	Sep. 30, 2011 ThinkPetsAcquisition [Member]	Sep. 30, 2012 ThinkPetsAcquisition [Member]	Sep. 30, 2011 ThinkPetsAcquisition [Member]	Sep. 30, 2012 AVC Acquisition [Member]	Sep. 30, 2012 AVC Acquisition [Member] Hospital	Sep. 30, 2012 Laboratories Acquisitions [Member] Laboratory
Business Acquisition Summary Of Acquired Properties [Line Items]
Number of Businesses Acquired			24							44
Annualized Revenue At Acquisition CAD										$ 95,000,000
Business Acquisition, Purchase Price Allocation, Goodwill, Expected Tax Deductible Amount				40,000,000			821,000		362,000	362,000
Payments To Acquire Real Estate For Use By Owner	1,602,000	1,900,000
Preliminary Purchase Price CAD										81,000,000
Business Acquisition, Cost of Acquired Entity, Cash Paid	108,031,000	189,255,000		51,744,000			7,468,000		48,819,000	48,819,000
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned							10,500,000
Business Acquisition Cost Of Acquired Entity Cash Paid For Hold Backs				1,475,000			1,050,000
Business Acquisition, Contingent Consideration, at Fair Value	(934,000)	(481,000)		934,000
Business Combination, Consideration Transferred				54,153,000			19,018,000		74,734,000	74,734,000
Business Acquisition, Purchase Price Allocation, Tangible Assets				1,995,000			2,078,000		11,743,000	11,743,000
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets				9,184,000			7,221,000		23,561,000	23,561,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount				42,974,000			11,194,000		77,565,000	77,565,000
Business Acquisition, Purchase Price Allocation, Liabilities Assumed							(1,475,000)		(18,124,000)	(18,124,000)
business acquisition purchase price allocation total									94,745,000	94,745,000
Noncontrolling Interest, Increase from Business Combination	(8,161,000)	0								(8,161,000)
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value	(11,850,000)	0							(11,850,000)	(11,850,000)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net				54,153,000			19,018,000		74,734,000	74,734,000
Business Acquisitions Cash Paid To Debtholders									25,915,000	25,915,000
Business Combination, Acquisition Related Costs						35,000		1,000,000	161,000	500,000
Business Acquisition, Percentage of Voting Interests Acquired							100.00%
Business Acquisition Cost Of Acquired Entity Preliminary Purchase Price					81,000,000		21,000,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares							473,389
business acquisition cash including acquired cash							10,500,000
Number Of Acquired Hospitals Relocated To Existing Hospitals			(4)
Number Of Properties Sold Closed Or Merged			(4)
Change In Number Of Animal Hospitals Owned During The Period			60
Number Of Laboratories Created											2
US Annualized Revenue At Acquisition										$ 95,000,000