ENVIRONMENTAL REMEDIATION LIABILITIES (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)
Property, Plant and Equipment [Line Items]
Environmental remediation expense	$ 11.9
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