Summary of Significant Accounting Policies - Prepaid Logging Roads (Details)	12 Months Ended
	Dec. 31, 2018
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Harvested in months, to be recorded as prepaid logging roads	24 months
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Harvested in months, to be recorded as prepaid logging roads	60 months