Supplemental Cash Flow Information (Summary Of Supplemental Cash Flow Information) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash Paid During The Period For
Interest	$ 13,204	$ 10,012
Income taxes, net of refunds	16,778	9,372
Noncash Investing and Financing Activities
Increase (decrease) in accounts payable associated with acquisition of property and equipment	958	185
Capital lease obligations	168	326
Effect Of Acquisitions And Related Transactions [Abstract]
Assets acquired, net of cash and adjustments	23,759	310,191
Liabilities assumed and noncontrolling interests	(9,491)	(121,691)
Payment of purchase price payable	1,829	0
Payment for interests in surgery centers and related transactions	$ 16,097	$ 188,500