Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 162,510	$ 157,193	$ 154,954
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	108,931	106,273	100,803
Goodwill impairment		1,684
Amortization of debt issuance costs and other non-cash interest	4,331	4,250	4,017
Expenses associated with debt refinancing transactions			3,838
Deferred income taxes	19,321	26,203	22,622
Other non-cash items	1,559	645	503
Income tax benefit of equity compensation	(1,962)	(4,371)	(6,896)
Non-cash equity compensation	10,384	9,646	9,828
Changes in assets and liabilities, net:
Accounts receivable, prepaid expenses and other assets	46,941	(70,964)	20,767
Accounts payable, accrued expenses and other liabilities	(2,456)	21,049	(2,672)
Income taxes payable	1,517	3,907	6,927
Net cash provided by operating activities	351,076	255,515	314,691
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for facility development and expansions	(125,682)	(101,820)	(94,313)
Expenditures for other capital improvements	(48,258)	(41,843)	(48,644)
Decrease in restricted cash	1,749
Proceeds from sale of assets	885	86	273
Increase in other assets	(2,248)	(1,875)	(2,285)
Payments received on direct financing lease and notes receivable	1,515	1,229	1,089
Net cash used in investing activities	(172,039)	(144,223)	(143,880)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of debt	383,623	171,167	587,478
Principal repayments of debt	(296,589)	(165,000)	(631,334)
Payment of debt issuance and other refinancing and related costs			(11,485)
Proceeds from exercise of stock options	2,137	6,601	15,166
Purchase and retirement of common stock	(239,847)	(148,830)	(125,701)
Income tax benefit of equity compensation	1,962	4,371	6,896
Net cash used in financing activities	(148,714)	(131,691)	(158,980)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	30,323	(20,399)	11,831
CASH AND CASH EQUIVALENTS, beginning of year	25,509	45,908	34,077
CASH AND CASH EQUIVALENTS, end of year	55,832	25,509	45,908
Cash paid during the period for:
Interest (net of amounts capitalized of $1,584, $3,922, and $1,582 in 2011, 2010, and 2009, respectively)	71,002	69,121	74,466
Income taxes	$ 70,341	$ 61,396	$ 63,534