ENVIRONMENTAL AND NATURAL RESOURCE DAMAGE LIABILITIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2020
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