Supplemental Cash Flow Information (Summary Of Supplemental Cash Flow Information) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash Paid During The Period For
Interest	$ 14,786	$ 13,815	$ 12,219
Income taxes, net of refunds	19,615	10,232	16,776
Noncash Investing and Financing Activities
Increase (decrease) in accounts payable associated with acquisition of property and equipment	248	659	164
Capital lease obligations	1,096	466	4,057
Restricted stock vested	4,835	4,476	48
Effect Of Acquisitions And Related Transactions [Abstract]
Assets acquired, net of cash and adjustments	470,172	408,429	94,686
Liabilities assumed and noncontrolling interests	(194,613)	(163,970)	(37,101)
Notes payable and other obligations	1,829	(5,236)	(3,895)
Payment for interests in surgery centers and related transactions	$ 277,388	$ 239,223	$ 53,690