ASSET RETIREMENT OBLIGATIONS (Narrative) (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) a item property	Dec. 31, 2019 USD ($)
Asset Retirement Obligations [Line Items]
Reclamation activities	$ 12,820,000	$ 12,457,000
California [Member]
Asset Retirement Obligations [Line Items]
Reclamation activities	$ 2,563,000	$ 3,354,000
Adjacent aggregates sites | property	2
Property, acres | a	90
Number of aggregates locations | item	2