ASSET RETIREMENT OBLIGATIONS (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) a item property	Jun. 30, 2019 USD ($)
Asset Retirement Obligations [Line Items]
Reclamation activities	$ 3,354	$ 3,388	$ 8,588	$ 6,966
California [Member]
Asset Retirement Obligations [Line Items]
Reclamation activities			$ 2,152	$ 2,015
Adjacent aggregates sites | property			2
Property, acres | a			90
Number of aggregates locations | item			3