UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ 16,545	$ (27,160)
Adjustments to reconcile net income (loss) to net cash from operating activities:
Depreciation and amortization	216,932	215,655
Goodwill impairment charge	0	34,013
Allowance for doubtful accounts	5,635	6,203
Amortization of deferred financing costs and debt discount	2,562	2,685
Accretion of environmental liabilities	7,053	7,529
Changes in environmental liability estimates	(312)	(349)
Deferred income taxes	184	(28,826)
Stock-based compensation	9,212	7,735
Excess tax benefit of stock-based compensation	0	(21)
Net tax deficiency on stock based awards	0	(642)
Other expense	2,814	1,247
Gain on sale of business	(31,645)	(16,431)
Loss on early extinguishment of debt	7,891	0
Environmental expenditures	(10,078)	(9,374)
Changes in assets and liabilities, net of acquisitions
Accounts receivable and unbilled accounts receivable	(38,122)	(32,944)
Inventories and supplies	(4,975)	(13,722)
Other current assets	18,305	5,619
Accounts payable	(7,085)	(11,951)
Other current and long-term liabilities	26,553	39,561
Net cash from operating activities	221,469	178,827
Cash flows used in investing activities:
Additions to property, plant and equipment	(127,736)	(175,348)
Proceeds from sale and disposal of fixed assets	5,375	3,982
Acquisitions, net of cash acquired	(44,432)	(207,089)
Proceeds on sale of business	46,339	47,134
Additions to intangible assets, including costs to obtain or renew permits	(1,348)	(1,920)
Purchases of available-for-sale securities	0	(598)
Proceeds from sale of investments	376	0
Net cash used in investing activities	(121,426)	(333,839)
Cash flows from financing activities:
Change in uncashed checks	(8,657)	(7,084)
Proceeds from exercise of stock options	46	230
Issuance of restricted shares, net of shares remitted	(2,321)	(2,500)
Repurchases of common stock	(24,465)	(15,869)
Deferred financing costs paid	(5,746)	(2,614)
Excess tax benefit of stock-based compensation	0	21
Premiums paid on early extinguishment of debt	(6,028)	0
Principal payment on debt	(401,000)	0
Issuance of senior secured notes, net of discount	399,000	0
Issuance of senior unsecured notes, including premium	0	250,625
Net cash (used in) from financing activities	(49,171)	222,809
Effect of exchange rate change on cash	3,789	5,352
Increase in cash and cash equivalents	54,661	73,149
Cash and cash equivalents, beginning of period	306,997	184,708
Cash and cash equivalents, end of period	361,658	257,857
Cash payments for interest and income taxes:
Interest paid	67,550	66,261
Income taxes paid	14,321	27,196
Non-cash investing and financing activities:
Accrual for repurchased shares	0	479
Property, plant and equipment accrued	14,509	18,181
Transfer of inventory to property, plant and equipment	12,641	0
Receivable for estimated purchase price adjustment	$ 0	$ 1,910