Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net income (loss)	$ 34,368	$ (1,943)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	89,520	67,764
Accretion on asset retirement obligation	56	65
Change in allowance for doubtful accounts	447	(1,081)
Amortization of deferred financing costs	1,392	967
Amortization and retirement of discount or premium on notes	(102)	6,484
Non-cash compensation	5,821	3,758
Loss on early extinguishment of debt (non-cash)		3,940
Premium on retirement of 11.625% senior secured notes		36,179
(Gain) loss on disposal of assets	2,699	(763)
Deferred income taxes	19,949	(6,088)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	16,180	(48,744)
Inventories	(4,831)	(4,106)
Prepaid expenses and other current assets	(1,048)	(1,102)
Other assets	1,237	(8,531)
Accounts payable	(2,049)	(690)
Excess tax expense (benefit) from exercise of employee stock options / vesting of restricted stock		(3,508)
Income tax payable	(1,306)	4,793
Other liabilities	3,297	(2,328)
Accrued expenses	11,909	10,515
Net cash provided by operating activities	177,539	55,581
Cash flows from investing activities:
Purchase of property and equipment	(86,733)	(114,873)
Proceeds from sale of assets	4,219	17,996
Payments for other long-term assets	(351)	(287)
Payments for businesses, net of cash acquired	(41,769)	(10)
Net cash used in investing activities	(124,634)	(97,174)
Cash flows from financing activities:
Proceeds from debt		498,850
Payments of debt	(19,866)	(238,291)
Premium on retirement of 11.625% senior secured notes		(36,179)
Purchase of treasury stock	(8,472)	(1,761)
Excess tax (expense) benefit from exercise of employee stock options / vesting of restricted stock		3,508
Tax withholding from exercise of stock options	(128)	(2,529)
Exercise of employee stock options	794	5,407
Deferred loan costs and other financing activities	(142)	(14,420)
Net cash provided by (used in) financing activities	(27,814)	214,585
Net increase in cash and equivalents	25,091	172,992
Cash and cash equivalents - beginning of period	78,458	47,918
Cash and cash equivalents - end of period	$ 103,549	$ 220,910