REVENUE (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	100.00%	100.00%
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage Of Company-Wide Revenue	100.00%	100.00%
Government Customer [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	14.00%	14.00%
Heavy Manufacturing [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	17.00%	18.00%
Light Manufacturing [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	10.00%	11.00%
Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	5.00%	5.00%
Healthcare Customer [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	6.00%	5.00%
Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	8.00%	8.00%
Retail/Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	7.00%	7.00%
Contractors [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	8.00%	8.00%
Natural Resources [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	4.00%	4.00%
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	21.00%	20.00%
Other businesses
Disaggregation of Revenue [Line Items]
Percentage Of Company-Wide Revenue	23.00%	22.00%
United States
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	100.00%	100.00%
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage Of Company-Wide Revenue	72.00%	72.00%
United States | Government Customer [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	18.00%	18.00%
United States | Heavy Manufacturing [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	19.00%	19.00%
United States | Light Manufacturing [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	12.00%	13.00%
United States | Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	6.00%	6.00%
United States | Healthcare Customer [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	7.00%	7.00%
United States | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	10.00%	9.00%
United States | Retail/Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	9.00%	8.00%
United States | Contractors [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	10.00%	10.00%
United States | Natural Resources [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	3.00%	3.00%
United States | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	6.00%	7.00%
Canada
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	100.00%	100.00%
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage Of Company-Wide Revenue	5.00%	6.00%
Canada | Government Customer [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	6.00%	6.00%
Canada | Heavy Manufacturing [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	20.00%	20.00%
Canada | Light Manufacturing [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	6.00%	6.00%
Canada | Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	8.00%	7.00%
Canada | Healthcare Customer [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	0.00%	0.00%
Canada | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	9.00%	10.00%
Canada | Retail/Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	4.00%	4.00%
Canada | Contractors [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	10.00%	11.00%
Canada | Natural Resources [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	33.00%	32.00%
Canada | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue From Contract With Customer, Excluding Assessed Tax, Percentage	4.00%	4.00%