CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 38,716	$ 18,514
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation and amortization	79,654	76,903
Provision for doubtful accounts	9,766	5,157
Amortization of debt discount and debt issuance costs	2,068	1,420
Stock-based compensation	2,744	2,660
Deferred income taxes	136	177
Equity in earnings of an unconsolidated affiliate	(3,011)	(1,484)
Gain on disposition of long-lived assets		(2,397)
Changes in operating assets and liabilities, excluding the effects of acquisitions:
Accounts receivable	(15,844)	(22,088)
Materials and supplies, prepayments, and other current assets	(3,404)	13,670
Income tax receivable	11,545
Accounts payable and accrued liabilities, advance payments and deposits and other current liabilities	272	(13,478)
Accrued taxes	17,505	7,373
Other	(2,672)	(1,690)
Net cash provided by operating activities	137,475	84,737
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(50,505)	(65,850)
Cash acquired in business combinations		4,087
Proceeds from disposition of long-lived assets		1,200
Decrease in restricted cash		467
Net cash used in investing activities	(50,505)	(60,096)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from borrowing under term loan	275,000
Proceeds from borrowings under revolver loan	46,378	93,153
Principal repayments of term loan	(256,873)	(9,984)
Principal repayments of revolver loan	(74,534)	(79,619)
Proceeds from stock option exercises	1,240	193
Dividends paid on common stock	(10,692)	(10,159)
Distributions to non-controlling interests	(2,010)	(2,531)
Payments of debt issuance costs	(3,564)	(1,020)
Repurchase of non-controlling interests	(80)	(446)
Investments made by non-controlling interests	1,040	684
Purchase of common stock	(202)	(129)
Net cash used in financing activities	(24,297)	(9,858)
NET CHANGE IN CASH AND CASH EQUIVALENTS	62,673	14,783
CASH AND CASH EQUIVALENTS, beginning of the period	48,735	37,330
CASH AND CASH EQUIVALENTS, end of the period	$ 111,408	$ 52,113