Summary of Significant Accounting Policies (Details Textual) (USD $) Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Segment Hospitals States ReportingUnits	Dec. 31, 2010	Dec. 31, 2009
Summary of Significant Accounting Policies (Textual) [Abstract]
Number of animal hospitals where management services are provided	170
Number of states in which management services are provided to animal hospitals	15
Number of Canadian provinces in which management services are provided to animal hospitals	1
Maturity period of cash equivalents	Less than 90 days
Depreciation and amortization of property under capital leases	$ 43,600,000	$ 36,700,000	$ 31,800,000
Accumulated amortization on building and equipment held under capital leases	5,500,000	4,600,000
Number of reporting units	4
Goodwill impairment	21,310,000
Likelihood of benefit amount being realized upon settlement in order to be recognized as a tax benefit	Greater than 50 percent
Valuation allowance for notes receivable	0	0
Notes bearing interest rate, minimum	3.90%
Notes bearing interest rate, maximum	8.00%
Accumulated amortization of deferred financing cost	482,000	574,000
Total marketing and advertising expense included in direct costs	25,200,000	21,700,000	19,900,000
Total marketing and advertising expenses included in selling, general and administrative expense	3,200,000	2,800,000	2,000,000
Accrued warranty costs	50,000	66,000
Common shares excluded from the computation of diluted earnings per share	1,200	11,763	48,008
Recognition of previously deferred revenue resulting from error correction	4,000,000
Recognition of previously deferred costs in Medical Technology segment resulting from error correction	3,800,000
Temporary equity from noncontrolling interests		5,800,000
Non-controlling interests in permanent equity to other liabilities		$ 506,000