UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ 4,487	$ (16,905)
Adjustments to reconcile net loss to net cash from operating activities:
Depreciation and amortization	143,943	142,295
Allowance for doubtful accounts	3,580	3,228
Amortization of deferred financing costs and debt discount	1,660	1,772
Accretion of environmental liabilities	4,706	5,053
Changes in environmental liability estimates	(129)	(315)
Deferred income taxes	190	(6,521)
Stock-based compensation	5,172	4,739
Excess tax benefit of stock-based compensation	0	(2)
Net tax deficiency on stock based awards	0	(603)
Other expense	2,382	1,049
Gain on sale of business	(31,722)	0
Loss on early extinguishment of debt	6,045	0
Environmental expenditures	(6,102)	(6,454)
Changes in assets and liabilities, net of acquisitions
Accounts receivable and unbilled accounts receivable	(31,154)	993
Inventories and supplies	(6,307)	(1,113)
Other current assets	13,918	(4,789)
Accounts payable	(2,686)	(8,397)
Other current and long-term liabilities	8,948	6,021
Net cash from operating activities	116,931	120,051
Cash flows used in investing activities:
Additions to property, plant and equipment	(88,742)	(123,529)
Proceeds from sales of fixed assets	2,121	2,668
Acquisitions, net of cash acquired	(9,277)	(58,989)
Proceeds on sale of businesses, net of transactional costs	46,391	0
Additions to intangible assets, including costs to obtain or renew permits	(1,239)	(973)
Purchases of available-for-sale securities	0	(598)
Proceeds from sale of investments	376	0
Net cash used in investing activities	(50,370)	(181,421)
Cash flows from financing activities:
Change in uncashed checks	(8,361)	(11,022)
Proceeds from exercise of stock options	46	184
Issuance of restricted shares, net of shares remitted	(2,132)	(1,879)
Repurchases of common stock	(12,257)	(10,134)
Deferred financing costs paid	(4,727)	(2,614)
Excess tax benefit of stock-based compensation	0	2
Premiums paid on early extinguishment of debt	(4,665)	0
Principal payment on debt	(296,202)	0
Issuance of senior secured notes, net of discount	399,000	0
Issuance of senior unsecured notes, including premium	0	250,625
Net cash from financing activities	70,702	225,162
Effect of exchange rate change on cash	2,106	4,423
Increase in cash and cash equivalents	139,369	168,215
Cash and cash equivalents, beginning of period	306,997	184,708
Cash and cash equivalents, end of period	446,366	352,923
Cash payments for interest and income taxes:
Interest paid	50,432	44,275
Income taxes paid	13,407	23,872
Non-cash investing and financing activities:
Property, plant and equipment accrued	16,213	24,187
Transfer of inventory to property, plant and equipment	$ 12,641	$ 0