Supplemental Cash Flow Information (Summary Of Supplemental Cash Flow Information) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash Paid During The Period For
Interest	$ 13,815	$ 12,219	$ 7,854
Income taxes, net of refunds	10,232	16,776	19,336
Noncash Investing and Financing Activities
Increase (decrease) in accounts payable associated with acquisition of property and equipment	659	164	(1,892)
Capital lease obligations	466	4,057	8,222
Restricted stock vested	4,476	48	90
Effect Of Acquisitions And Related Transactions [Abstract]
Assets acquired, net of cash and adjustments	408,429	94,686	170,783
Liabilities assumed and noncontrolling interests	(163,970)	(37,101)	(74,957)
Notes payable and other obligations	(5,236)	(3,895)	0
Payment for interests in surgery centers and related transactions	$ 239,223	$ 53,690	$ 95,826