Supplemental Cash Flow Information (Summary Of Supplemental Cash Flow Information) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash Paid During The Period For
Interest	$ 8,178	$ 6,899
Income taxes, net of refunds	11,963	5,614
Noncash Investing and Financing Activities
Increase (decrease) in accounts payable associated with acquisition of property and equipment	(225)	(867)
Capital lease obligations	48	188
Effect Of Acquisitions And Related Transactions [Abstract]
Assets acquired, net of cash and adjustments	12,911	76,923
Liabilities assumed and noncontrolling interests	(4,768)	(31,249)
Payment of purchase price payable	1,829	0
Payment for interests in surgery centers and related transactions	$ 9,972	$ 45,674