ENVIRONMENTAL AND NATURAL RESOURCE DAMAGE LIABILITIES - Narrative (Details)	9 Months Ended
	Sep. 30, 2021
Minimum | Millsite Cleanup and Natural Resource Damages Restoration
Property, Plant and Equipment [Line Items]
Natural resource damages restoration monitoring term	2 years
Minimum | Port Gamble Location
Property, Plant and Equipment [Line Items]
Natural resource damages restoration monitoring term	10 years
Maximum | Millsite Cleanup and Natural Resource Damages Restoration
Property, Plant and Equipment [Line Items]
Natural resource damages restoration monitoring term	3 years
Maximum | Port Gamble Location
Property, Plant and Equipment [Line Items]
Natural resource damages restoration monitoring term	15 years