Consolidated Statements of Cash Flows - Entity [Domain] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 122,580	$ 107,470
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	67,085	57,136
Asset impairments	955	2,238
Amortization of debt issuance costs and other non-cash interest	1,552	1,548
Deferred income taxes	2,611	93
Non-cash revenue and other income	(991)	(2,889)
Income tax benefit of equity compensation	(475)	(117)
Non-cash equity compensation	7,708	6,924
Other expenses and non-cash items	2,213	2,625
Changes in assets and liabilities, net:
Accounts receivable, prepaid expenses and other assets	6,124	(10,196)
Accounts payable, accrued expenses and other liabilities	5,692	(30,476)
Income taxes payable	193	(450)
Net cash provided by operating activities	215,247	133,906
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for facility development and expansions	(112,548)	(27,750)
Expenditures for other capital improvements	(25,889)	(20,852)
Capitalized lease payments	(24,592)
Decrease in restricted cash	603	2,983
Proceeds from sale of assets	57	704
Decrease in other assets	1,922	2,041
Payments received on direct financing lease and notes receivable	1,091	967
Net cash used in investing activities	(159,356)	(41,907)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of debt	160,000	75,000
Principal repayments of debt	(122,000)	(85,000)
Payment of debt issuance and other refinancing and related costs	(134)
Dividends paid	(124,261)	(115,469)
Income tax benefit of equity compensation	475	117
Purchase and retirement of common stock	(9,432)	(2,803)
Decrease in restricted cash for dividends	500
Proceeds from exercise of stock options	5,637	4,852
Net cash used in financing activities	(89,215)	(123,303)
NET DECREASE IN CASH AND CASH EQUIVALENTS	(33,324)	(31,304)
CASH AND CASH EQUIVALENTS, beginning of period	74,393	77,919
CASH AND CASH EQUIVALENTS, end of period	41,069	46,615
Cash paid during the period for:
Interest (net of amounts capitalized of $2,792 and $1,002 in 2015 and 2014, respectively)	18,609	19,912
Income taxes	$ 6,706	$ 8,697