Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities:
Net income	$ 127,983	$ 99,707
Adjustments to reconcile net income to net cash provided by operating activities:
Loss (gain) on disposal of assets	742	572
Depreciation	108,843	99,349
Amortization of intangibles	14,788	10,800
Deferred income taxes, net of acquisitions	36,960	15,925
Loss on redemption of 2026 Convertible Senior Notes, net of make-whole payment		2,255
Amortization of debt issuance costs	1,005	1,332
Amortization of debt discount		1,245
Equity-based compensation	8,906	8,488
Interest income on restricted assets	(355)	(397)
Closure and post-closure accretion	1,451	1,323
Excess tax benefit associated with equity-based compensation	(4,500)	(8,935)
Net change in operating assets and liabilities, net of acquisitions	1,901	14,358
Net cash provided by operating activities	297,724	246,022
Cash flows from investing activities:
Payments for acquisitions, net of cash acquired	(247,962)	(17,391)
Capital expenditures for property and equipment	(84,051)	(86,121)
Proceeds from disposal of assets	3,238	5,786
Decrease (increase) in restricted assets, net of interest income	2,241	(1,048)
Increase in other assets	(1,706)	(2,034)
Net cash used in investing activities	(328,240)	(100,808)
Cash flows from financing activities:
Proceeds from long-term debt	515,500	331,253
Principal payments on notes payable and long-term debt	(343,726)	(384,346)
Change in book overdraft	(937)	(374)
Proceeds from option and warrant exercises	4,956	23,244
Excess tax benefit associated with equity-based compensation	4,500	8,935
Payments for repurchase of common stock	(85,068)	(116,285)
Payments for cash dividends	(25,497)
Tax withholdings related to net share settlements of restricted stock units	(5,436)	(3,724)
Distributions to noncontrolling interests	(675)
Debt issuance costs	(6,414)
Net cash provided by (used in) financing activities	57,203	(141,297)
Net increase in cash and equivalents	26,687	3,917
Cash and equivalents at beginning of period	9,873	9,639
Cash and equivalents at end of period	36,560	13,556
Non-cash financing activity:
Liabilities assumed and notes payable issued to sellers of businesses acquired	$ 144,386	$ 13,243