MERGER WITH POPE RESOURCES - Narrative (Details) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	May 08, 2020 fund
Business Acquisition [Line Items]
Costs related to the merger with Pope Resources	$ 0	$ 430			$ 0	$ 16,415
Net (loss) income	$ 110,512	(9,498)			188,963	17,378
Merger with Pope Resources
Business Acquisition [Line Items]
Number of timber funds acquired | fund							3
Costs related to the merger with Pope Resources		400	$ 13,500	$ 2,500
Increase in higher and better use timberlands from purchase price allocation					8,200
Increase (decrease) in timber and timberlands					1,100
Merger with Pope Resources | Acquisition-related Transaction Costs
Business Acquisition [Line Items]
Net (loss) income		$ 400				$ 31,600
Core Timberlands
Business Acquisition [Line Items]
Increase (decrease) in timber and timberlands					(15,500)
Timber Funds
Business Acquisition [Line Items]
Increase (decrease) in timber and timberlands					$ 16,600