CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenues	$ 202,667	$ 198,547	$ 574,344	$ 549,670
Operating expenses:
Cost of operations	130,406	131,273	382,386	377,707
General and administration	25,014	22,536	74,240	67,423
Depreciation and amortization	23,799	20,940	67,281	58,144
Withdrawal costs - multiemployer pension plan	0	3,591	0	3,591
Southbridge Landfill closure charge	2,642	625	3,815	2,097
Expense from acquisition activities	173	1,097	1,533	2,237
Total operating expenses	182,034	180,062	529,255	511,199
Operating income	20,633	18,485	45,089	38,471
Other expense (income):
Interest income	(107)	(66)	(203)	(287)
Interest expense	5,406	6,235	16,869	18,849
Other income	(157)	(248)	(606)	(960)
Other expense, net	5,142	5,921	16,060	17,602
Income before income taxes	15,491	12,564	29,029	20,869
Provision (benefit) for income taxes	374	178	840	(1,718)
Net income	$ 15,117	$ 12,386	$ 28,189	$ 22,587
Basic earnings per share attributable to common stockholders:
Weighted average common shares outstanding	48,370	47,690	48,241	47,029
Basic earnings per common share (in dollars per share)	$ 0.31	$ 0.26	$ 0.58	$ 0.48
Diluted earnings per share attributable to common stockholders:
Weighted average common shares outstanding	48,619	48,361	48,481	47,660
Diluted earnings per common share (in dollars per share)	$ 0.31	$ 0.26	$ 0.58	$ 0.47