SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details)	12 Months Ended
	Dec. 31, 2020
Stumpage Pay-as-Cut
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment period after satisfaction of obligation	10 days
Stumpage Pay-as-Cut | Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Initial payment, percentage of estimated contract value	5.00%
Stumpage Pay-as-Cut | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Initial payment, percentage of estimated contract value	20.00%
Total Delivered | Domestic
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment period after satisfaction of obligation	30 days
Total Delivered | Export
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment period after satisfaction of obligation, letter of credit	30 days