Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (94,694)	$ 233,327	$ 196,005
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Loss on disposal of assets and impairments	518,657	8,239	2,853
Depreciation	240,357	230,944	218,454
Amortization of intangibles	29,077	27,000	25,410
Deferred income taxes, net of acquisitions	(132,454)	31,031	38,680
Amortization of debt issuance costs	3,097	3,085	3,655
Equity-based compensation	20,318	18,446	15,397
Interest income on restricted assets	(428)	(446)	(386)
Interest accretion	6,761	5,076	4,812
Excess tax benefit associated with equity-based compensation	(2,069)	(7,518)	(3,765)
Payment of contingent consideration recorded in earnings		(1,074)	(5,059)
Adjustments to contingent consideration	(22,180)	(3,450)	1,276
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	17,348	(22,168)	1,612
Prepaid expenses and other current assets	(2,780)	(3,868)	1,696
Accounts payable	(16,674)	10,173	(26,993)
Deferred revenue	4,377	8,571	1,403
Accrued liabilities	8,217	4,985	6,117
Other long-term liabilities	69	2,724	2,894
Net cash provided by operating activities	576,999	545,077	484,061
Cash flows from investing activities:
Payments for acquisitions, net of cash acquired	(230,517)	(126,181)	(64,156)
Proceeds from adjustment to acquisition consideration			18,000
Capital expenditures for property and equipment	(238,833)	(241,277)	(209,874)
Proceeds from disposal of assets	2,883	9,421	11,019
Change in restricted assets, net of interest income	(2,225)	(4,475)	(646)
Other	(1,842)	(896)	(5,358)
Net cash used in investing activities	(470,534)	(363,408)	(251,015)
Cash flows from financing activities:
Proceeds from long-term debt	1,489,500	432,500	327,600
Principal payments on notes payable and long-term debt	(1,429,195)	(525,909)	(493,560)
Payment of contingent consideration recorded at acquisition date	(2,190)	(24,847)	(23,941)
Change in book overdraft	(89)	(11)	(110)
Proceeds from option and warrant exercises	572	3,375	2,464
Excess tax benefit associated with equity-based compensation	2,069	7,518	3,765
Payments for repurchase of common stock	(91,165)	(7,317)
Payments for cash dividends	(65,990)	(58,906)	(51,213)
Tax withholdings related to net share settlements of restricted stock units	(6,447)	(6,814)	(5,439)
Distributions to noncontrolling interests	(42)	(371)	(198)
Debt issuance costs	(6,867)	(125)	(2,035)
Net cash used in financing activities	(109,844)	(180,907)	(242,667)
Net increase (decrease) in cash and equivalents	(3,379)	762	(9,621)
Cash and equivalents at beginning of year	14,353	13,591	23,212
Cash and equivalents at end of year	10,974	14,353	13,591
SUPPLEMENTARY DISCLOSURES OF CASH FLOW INFORMATION AND NON-CASH TRANSACTIONS:
Cash paid for income taxes	102,279	116,239	81,710
Cash paid for interest	55,674	60,224	66,985
In connection with its acquisitions, the Company assumed liabilities as follows:
Fair value of assets acquired	433,227	172,875	67,271
Cash paid for current year acquisitions	(230,517)	(126,181)	(64,156)
Liabilities assumed and notes payable issued to sellers of businesses acquired	$ 202,710	$ 46,694	$ 3,115