SIGNIFICANT ACCOUNTING POLICIES (Property, Plant and Equipment) (Details)	12 Months Ended
	Dec. 31, 2017
Solar equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	30 years
Minimum | Buildings
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	30 years
Minimum | Leasehold and building improvements
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	2 years
Minimum | Camp equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	8 years
Minimum | Vehicles
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	3 years
Minimum | Capitalized software and computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	3 years
Minimum | Containers and railcars
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	15 years
Minimum | All other equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	8 years
Minimum | Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	5 years
Maximum | Buildings
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	42 years
Maximum | Leasehold and building improvements
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	45 years
Maximum | Camp equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	15 years
Maximum | Vehicles
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	15 years
Maximum | Capitalized software and computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	5 years
Maximum | Containers and railcars
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	20 years
Maximum | All other equipment
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	25 years
Maximum | Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	8 years
Weighted average | Leasehold and building improvements
Property, Plant and Equipment [Line Items]
Estimated useful life (in years)	9 years 219 days