REVENUES - Geography (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of revenue
Revenue	$ 240,720	$ 131,037
United States
Disaggregation of revenue
Revenue	213,474	116,064
Canada
Disaggregation of revenue
Revenue	19,894	14,973
EMEA
Disaggregation of revenue
Revenue	5,239
Other
Disaggregation of revenue
Revenue	2,113
Operating Segment | Environmental Services
Disaggregation of revenue
Revenue	126,745	92,332
Operating Segment | Environmental Services | United States
Disaggregation of revenue
Revenue	107,928	77,359
Operating Segment | Environmental Services | Canada
Disaggregation of revenue
Revenue	18,817	14,973
Operating Segment | Field and Industrial Services
Disaggregation of revenue
Revenue	113,975	38,705
Operating Segment | Field and Industrial Services | United States
Disaggregation of revenue
Revenue	105,546	$ 38,705
Operating Segment | Field and Industrial Services | Canada
Disaggregation of revenue
Revenue	1,077
Operating Segment | Field and Industrial Services | EMEA
Disaggregation of revenue
Revenue	5,239
Operating Segment | Field and Industrial Services | Other
Disaggregation of revenue
Revenue	$ 2,113