Revenue (Log Sale and Other Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 22,647	$ 28,008	$ 27,912	$ 24,987	$ 47,784	$ 18,803	$ 15,891	$ 17,345
Partnership Timber
Disaggregation of Revenue [Line Items]
Revenue									$ 45,422	$ 39,672	$ 36,275
Funds Timber
Disaggregation of Revenue [Line Items]
Revenue									49,819	33,842	21,029
Timber deed sale revenue | Partnership Timber
Disaggregation of Revenue [Line Items]
Revenue									92	422	347
Timber deed sale revenue | Funds Timber
Disaggregation of Revenue [Line Items]
Revenue									11,440	2,337	1,440
Other revenue | Partnership Timber
Disaggregation of Revenue [Line Items]
Revenue									2,292	2,157	2,105
Other revenue | Funds Timber
Disaggregation of Revenue [Line Items]
Revenue									1,117	558	424
UNITED STATES | Log sale revenue - domestic | Partnership Timber
Disaggregation of Revenue [Line Items]
Revenue									34,789	28,126	26,710
UNITED STATES | Log sale revenue - domestic | Funds Timber
Disaggregation of Revenue [Line Items]
Revenue									27,981	15,490	16,229
Indirect | Log sale revenue - domestic | Partnership Timber
Disaggregation of Revenue [Line Items]
Revenue									8,249	8,967	7,113
Indirect | Log sale revenue - domestic | Funds Timber
Disaggregation of Revenue [Line Items]
Revenue									$ 9,281	$ 15,457	$ 2,936