REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	$ 743,290	$ 660,660	$ 599,309
Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	219,475	206,473
Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	343,399	286,262
Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	42,820	42,191
Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	137,596	125,734
Collection
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	377,839	306,939
Collection | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	154,805	136,661
Collection | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	223,034	170,278
Collection | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Collection | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Landfill
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	93,019	94,986
Landfill | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	19,362	28,419
Landfill | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	73,657	66,567
Landfill | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Landfill | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Transfer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	76,138	67,583
Transfer | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	44,413	39,991
Transfer | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	31,725	27,592
Transfer | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Transfer | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Customer solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	79,457	67,464
Customer solutions | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Customer solutions | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Customer solutions | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Customer solutions | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	79,457	67,464
Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	44,311	46,019
Recycling | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	5	5
Recycling | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	1,486	3,823
Recycling | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	42,820	42,191
Recycling | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Organics
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	56,326	54,174
Organics | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Organics | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Organics | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Organics | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	56,326	54,174
Transportation
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	12,624	18,366
Transportation | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Transportation | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	10,811	14,270
Transportation | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Transportation | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	1,813	4,096
Landfill gas-to-energy
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	3,576	5,129
Landfill gas-to-energy | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	890	1,397
Landfill gas-to-energy | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	2,686	3,732
Landfill gas-to-energy | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Landfill gas-to-energy | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0	0
Transferred at a point-in-time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	24,286	32,974
Transferred at a point-in-time | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	159	648
Transferred at a point-in-time | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	921	1,145
Transferred at a point-in-time | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	19,738	27,260
Transferred at a point-in-time | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	3,468	3,921
Transferred over time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	719,004	627,686
Transferred over time | Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	219,316	205,825
Transferred over time | Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	342,478	285,117
Transferred over time | Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	23,082	14,931
Transferred over time | Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	$ 134,128	$ 121,813