Acquisitions (Narrative) (Details) (USD $)	3 Months Ended				3 Months Ended		0 Months Ended		3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Contingent Purchase Price Payable [Member]	Mar. 31, 2011 Contingent Purchase Price Payable [Member]	Mar. 31, 2012 Controlling Interest [Member] Centers	Mar. 31, 2011 Controlling Interest [Member] Centers	Sep. 01, 2011 Acquired Nsc Centers [Member] Centers	Mar. 31, 2012 Acquired Nsc Centers [Member]	Mar. 31, 2012 Current Year Acquisitions [Member]	Mar. 31, 2012 Prior Year Acquisitions [Member]
Business Acquisition [Line Items]
Number of business acquisitions					2	1	17
Goodwill deductible for tax purposes	$ 7,579,000	$ 3,626,000
Payments to Acquire Businesses, Net of Cash Acquired	9,857,000	3,695,000							8,143,000	1,714,000
Additional Contingent Consideration								7,500,000
Purchase Price Placed in Escrow								3,500,000
Business Acquisition Purchase Price Allocation Maximum Amount for Working Capital Adjustments								500,000
Other operating expenses in acquisition related costs, primarily attorney fees	52,000	25,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			$ 3,522,000	$ 5,236,000