SEGMENT REPORTING - Schedule of Financial Information by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Segment Reporting Information [Line Items]
Gross revenues	$ 457,328	$ 417,101
Cost of operations	308,927	280,452
General and administration	58,128	56,486
Depreciation and amortization	77,982	71,491
Expense from acquisition activities	6,509	5,529
Organics facility closure charge	927	0
Operating income	4,855	3,143
Interest expense, net	13,993	11,598
Other income	(314)	(320)
Loss before income taxes	(8,824)	(8,135)
Capital expenditures	49,979	55,475
Total assets	3,270,449	3,205,870	$ 3,303,326
Solid waste
Segment Reporting Information [Line Items]
Gross revenues	368,529	334,904
Solid waste | Eastern
Segment Reporting Information [Line Items]
Gross revenues	111,287	104,740
Solid waste | Western
Segment Reporting Information [Line Items]
Gross revenues	162,448	152,316
Solid waste | Mid-Atlantic
Segment Reporting Information [Line Items]
Gross revenues	94,794	77,848
Resource Solutions
Segment Reporting Information [Line Items]
Gross revenues	88,799	82,197
Inter-company revenue
Segment Reporting Information [Line Items]
Gross revenues	(99,842)	(85,304)
Cost of operations	(99,842)	(85,304)
Inter-company revenue | Solid waste
Segment Reporting Information [Line Items]
Gross revenues	94,044	81,828
Inter-company revenue | Solid waste | Eastern
Segment Reporting Information [Line Items]
Gross revenues	27,510	26,289
Inter-company revenue | Solid waste | Western
Segment Reporting Information [Line Items]
Gross revenues	59,992	53,726
Inter-company revenue | Solid waste | Mid-Atlantic
Segment Reporting Information [Line Items]
Gross revenues	6,542	1,813
Inter-company revenue | Resource Solutions
Segment Reporting Information [Line Items]
Gross revenues	5,798	3,476
Operating Segments | Solid waste
Segment Reporting Information [Line Items]
Gross revenues	462,573	416,732
Cost of operations	328,998	295,237
General and administration	20,947	19,222
Depreciation and amortization	70,764	64,730
Expense from acquisition activities	1,902	3,654
Organics facility closure charge	0
Operating income	39,962	33,889
Interest expense, net	1,007	502
Capital expenditures	44,656	48,936
Total assets	2,801,489	2,591,161
Operating Segments | Solid waste | Eastern
Segment Reporting Information [Line Items]
Gross revenues	138,797	131,029
Cost of operations	100,901	95,653
General and administration	6,591	6,053
Depreciation and amortization	17,156	16,109
Expense from acquisition activities	64	396
Organics facility closure charge	0
Operating income	14,085	12,818
Interest expense, net	384	226
Capital expenditures	7,675	8,103
Total assets	549,868	538,730
Operating Segments | Solid waste | Western
Segment Reporting Information [Line Items]
Gross revenues	222,440	206,042
Cost of operations	151,775	140,412
General and administration	8,397	9,169
Depreciation and amortization	32,457	30,360
Expense from acquisition activities	122	844
Organics facility closure charge	0
Operating income	29,689	25,257
Interest expense, net	238	221
Capital expenditures	16,078	15,200
Total assets	1,117,182	1,131,276
Operating Segments | Solid waste | Mid-Atlantic
Segment Reporting Information [Line Items]
Gross revenues	101,336	79,661
Cost of operations	76,322	59,172
General and administration	5,959	4,000
Depreciation and amortization	21,151	18,261
Expense from acquisition activities	1,716	2,414
Organics facility closure charge	0
Operating income	(3,812)	(4,186)
Interest expense, net	385	55
Capital expenditures	20,903	25,633
Total assets	1,134,439	921,155
Operating Segments | Resource Solutions
Segment Reporting Information [Line Items]
Gross revenues	94,597	85,673
Cost of operations	78,859	70,032
General and administration	5,451	4,541
Depreciation and amortization	5,196	5,134
Expense from acquisition activities	17	992
Organics facility closure charge	927
Operating income	4,147	4,974
Interest expense, net	22	26
Capital expenditures	1,716	4,070
Total assets	277,422	276,983
Corporate Entities
Segment Reporting Information [Line Items]
Cost of operations	912	487
General and administration	31,730	32,723
Depreciation and amortization	2,022	1,627
Expense from acquisition activities	4,590	883
Organics facility closure charge	0
Operating income	(39,254)	(35,720)
Interest expense, net	12,964	11,070
Capital expenditures	3,607	2,469
Total assets	$ 191,538	$ 337,726