CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues	$ 599,309	$ 565,030	$ 546,500
Operating expenses:
Cost of operations	405,188	381,973	382,615
General and administration	79,243	75,356	72,892
Depreciation and amortization	62,102	61,856	62,704
Southbridge Landfill closure charge	65,183	0	0
Expense from divestiture, acquisition and financing costs	176	0	0
Environmental remediation charge	0	900	0
Contract settlement charge	0	0	1,940
Divestiture transactions	0	0	(5,517)
Total operating expenses	611,892	520,085	514,634
Operating (loss) income	(12,583)	44,945	31,866
Other expense (income):
Interest income	(273)	(290)	(330)
Interest expense	25,160	38,942	40,420
Loss on debt extinguishment	517	13,747	999
Loss on derivative instruments	0	0	227
Impairment of investments	0	0	2,099
Other income	(935)	(1,090)	(1,119)
Other expense, net	24,469	51,309	42,296
Loss before income taxes	(37,052)	(6,364)	(10,430)
(Benefit) provision for income taxes	(15,253)	494	1,351
Net loss	(21,799)	(6,858)	(11,781)
Less: Net (loss) income attributable to noncontrolling interests	0	(9)	1,188
Net loss attributable to common stockholders	(21,799)	(6,849)	(12,969)
Net loss attributable to common stockholders:
Net loss attributable to common stockholders	$ (21,799)	$ (6,849)	$ (12,969)
Weighted average common shares outstanding:
Basic and diluted (in shares)	41,846	41,233	40,642
Basic and diluted earnings per share:
Net loss per common share (in dollars per share)	$ (0.52)	$ (0.17)	$ (0.32)