Income Taxes - Income Tax Expense (Benefit) Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Tax at the federal statutory rate	$ 107	$ 2,326
State income taxes (net of federal benefit)	22	233
2017 qualified timber gains at the federal statutory rate of 23.8% (1)	(345)	0
Decrease in valuation allowance	(33)	(280)
Total income tax (benefit) expense	$ (249)	$ 2,279
Timber statutory federal rate		23.80%