Acquisitions (Fair Value Of Total Consideration Transferred And Major Class Of Consideration) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Acquired Nsc Centers [Member]
Business Acquisition [Line Items]
Accounts receivable		$ 16,032
Supplies, inventory, prepaid and other current assets		5,744
Investment in unconsolidated affiliates		10,710
Property and equipment		18,208
Goodwill		167,865
Other intangible assets		268
Accounts payable		(2,612)
Other accrued liabilities		(5,233)
Long-term debt		(2,900)
Other long-term liabililties		(1,895)
Total fair value		206,187
Less: Fair value attributable to noncontrolling interests		70,502
Acquisition date fair value of total consideration transferred		135,685
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Accounts receivable	11,572	7,837
Supplies, inventory, prepaid and other current assets	4,750	1,888
Investment in unconsolidated affiliates	0	0
Property and equipment	23,546	8,350
Goodwill	429,504	169,777
Other intangible assets	800	1,750
Accounts payable	(3,199)	(2,665)
Other accrued liabilities	(2,387)	(415)
Long-term debt	(6,954)	(5,698)
Other long-term liabililties	0	0
Total fair value	457,632	180,824
Less: Fair value attributable to noncontrolling interests	182,073	72,050
Acquisition date fair value of total consideration transferred	$ 275,559	$ 108,774