Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 31,680	$ 40,330
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	28,387	27,055
Expenses associated with debt refinancing transactions	1,541
Amortization of debt issuance costs and other non-cash interest	1,153	1,066
Deferred income taxes	(613)	6,046
Income tax benefit of equity compensation	(2,076)	(860)
Non-cash equity compensation	2,639	2,715
Other expenses and non-cash items	182	798
Changes in assets and liabilities, net:
Accounts receivable, prepaid expenses and other assets	20,276	44,959
Accounts payable, accrued expenses and other liabilities	(29,645)	(21,286)
Income taxes payable	14,783	10,130
Net cash provided by operating activities	68,307	110,953
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for facility development and expansions	(9,406)	(6,014)
Expenditures for other capital improvements	(13,458)	(6,728)
Proceeds from sale of assets	441	181
Increase in other assets	(830)	(228)
Payments received on direct financing lease	374	330
Net cash used in investing activities	(22,879)	(12,459)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of debt	618,500	29,421
Principal repayments of debt	(683,500)	(73,589)
Payment of debt issuance and other refinancing and related costs	(6,292)
Income tax benefit of equity compensation	2,076	860
Purchase and retirement of common stock	(2,391)	(43,678)
Proceeds from exercise of stock options	1,701	775
Net cash used in financing activities	(69,906)	(86,211)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(24,478)	12,283
CASH AND CASH EQUIVALENTS, beginning of period	55,832	25,509
CASH AND CASH EQUIVALENTS, end of period	31,354	37,792
Cash paid during the period for:
Interest (net of amounts capitalized of $497 and $106 in 2012 and 2011, respectively)	16,052	17,460
Income taxes paid (refund)	$ 1,198	$ (4)