Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	$ 9,533,000	$ 3,999,000	$ 5,510,000
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	2,868,000	1,708,000	378,000
Adjustments Related to Tax Withholding for Share-based Compensation	(8,216,000)	(2,673,000)	(2,310,000)
CashPaidToDebtHolders	(25,915,000)	(26,048,000)	(29,532,000)
Stock Issued During Period, Value, Acquisitions	(10,500,000)	0	0
Cash flows from operating activities:
Net income	50,716,000	99,860,000	114,158,000
Adjustments to reconcile net income to net cash provided by operating activities:
Asset Impairment Charges	123,573,000
Goodwill impairment	99,501,000	21,310,000	0
Depreciation and amortization	76,227,000	56,988,000	46,069,000
Amortization of debt issue costs	(1,278,000)	(1,445,000)	(862,000)
Provision for uncollectible accounts	6,396,000	6,742,000	7,366,000
Debt retirement costs	0	2,764,000	2,131,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain	(5,719,000)	0	0
Net loss on sale of assets	1,310,000	382,000	374,000
Share-based compensation	14,087,000	10,773,000	9,340,000
Deferred income taxes	33,398,000	(19,552,000)	(13,493,000)
Excess tax benefit from exercise of stock options	(2,868,000)	(1,708,000)	(378,000)
Other	(584,000)	(637,000)	(901,000)
Changes in operating assets and liabilities:
Trade accounts receivable	(1,640,000)	14,107,000	7,048,000
Inventory, prepaid expenses and other assets	(10,329,000)	(12,297,000)	(11,868,000)
Accounts payable and other accrued liabilities	(3,640,000)	5,415,000	(7,463,000)
Accrued payroll and related liabilities	(7,181,000)	(4,583,000)	385,000
Income taxes	(4,103,000)	(816,000)	12,603,000
Net cash provided by operating activities	237,253,000	191,051,000	168,073,000
Cash flows from investing activities:
Real estate acquired in connection with business acquisitions	(5,337,000)	(1,900,000)	(9,289,000)
Property and equipment additions	(76,807,000)	(63,485,000)	(61,951,000)
Proceeds from sale of assets	(115,000)	(465,000)	(939,000)
Other	(2,313,000)	(596,000)	(22,000)
Net cash used in investing activities	(219,258,000)	(271,310,000)	(150,174,000)
Cash flows from financing activities:
Repayment of debt	(60,775,000)	(98,990,000)	(555,529,000)
Proceeds from the issuance of long-term debt	50,000,000	150,000,000	500,000,000
Payment of financing costs	(122,000)	(2,944,000)	(9,112,000)
Proceeds from revolving credit facility	50,000,000	50,000,000	0
Repayment of revolving credit facility	(50,000,000)	(50,000,000)	0
Distributions to noncontrolling interest partners	(4,481,000)	(3,277,000)	(4,247,000)
Proceeds from issuance of common stock under stock incentive plans	9,533,000	3,999,000	5,510,000
Excess tax benefits from exercise of stock options	2,868,000	1,708,000	378,000
Stock repurchases	(8,159,000)	(2,673,000)	(2,310,000)
Other	(2,378,000)	(819,000)	(832,000)
Net cash provided by (used in) financing activities	(13,514,000)	47,004,000	(66,142,000)
Effect of currency exchange rate changes on cash and cash equivalents	303,000	(220,000)	188,000
(Decrease) increase in cash and cash equivalents	4,784,000	(33,475,000)	(48,055,000)
Cash and cash equivalents at beginning of year	63,651,000	97,126,000	145,181,000
Cash and cash equivalents at end of year	68,435,000	63,651,000	97,126,000
Supplemental disclosures of cash flow information:
Interest paid	15,407,000	15,088,000	13,357,000
Income taxes paid	61,481,000	55,660,000	77,210,000
Detail of acquisitions:
Fair value of assets acquired	220,526,000	254,781,000	139,085,000
Contingent consideration	(1,306,000)	(560,000)	(259,000)
Holdbacks	(3,475,000)	(1,500,000)	0
Liabilities assumed	24,403,000	22,677,000	29,443,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value	(11,850,000)	0	0
Noncontrolling Interest, Increase from Business Combination	(8,161,000)	0	0
Payments to Acquire Businesses, Net of Cash Acquired	(134,916,000)	(205,794,000)	(79,851,000)
Business Acquisition, Cost of Acquired Entity, Cash Paid		$ (203,996,000)	$ (79,851,000)