CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenues	$ 165,649	$ 154,016	$ 313,104	$ 287,818
Operating expenses:
Cost of operations	111,800	102,519	217,409	197,063
General and administration	20,793	18,794	41,820	37,638
Depreciation and amortization	17,386	15,868	33,370	29,717
Contract settlement charge	0	0	2,100	0
Southbridge Landfill closure charge	172	64,114	1,759	64,114
Development project charge	0	0	311	0
Expense from acquisition activities and other items	349	0	349	0
Total operating expenses	150,500	201,295	297,118	328,532
Operating income (loss)	15,149	(47,279)	15,986	(40,714)
Other expense (income):
Interest income	(79)	(52)	(108)	(121)
Interest expense	6,469	6,334	12,922	12,784
Loss on debt extinguishment	7,352	46	7,352	517
Other income	(342)	(326)	(431)	(405)
Other expense, net	13,400	6,002	19,735	12,775
Income (loss) before income taxes	1,749	(53,281)	(3,749)	(53,489)
Provision (benefit) for income taxes	45	394	(1,543)	411
Net income (loss)	$ 1,704	$ (53,675)	$ (2,206)	$ (53,900)
Basic earnings per share attributable to common stockholders:
Basic weighted average common share outstanding (in shares)	42,661	41,811	42,516	41,698
Basic earnings per common share (in dollars per share)	$ 0.04	$ (1.28)	$ (0.05)	$ (1.29)
Diluted earnings per share attributable to common stockholders:
Diluted weighted average shares outstanding (in shares)	43,916	41,811	42,516	41,698
Diluted earnings per common share (in dollars per share)	$ 0.04	$ (1.28)	$ (0.05)	$ (1.29)