Timberland Acquisitions - Summary of Timberland Acquisitions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) a	Dec. 31, 2017 USD ($) a	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Cost | $	$ 57,608	$ 242,910	$ 366,481
Acres | a	29,857	109,533
Florida
Business Acquisition [Line Items]
Cost | $	$ 35,560	$ 32,334
Acres | a	20,513	15,382
Georgia
Business Acquisition [Line Items]
Cost | $	$ 2,532	$ 147,833
Acres | a	2,232	68,473
South Carolina
Business Acquisition [Line Items]
Cost | $	$ 0	$ 39,884
Acres | a	0	17,651
Texas
Business Acquisition [Line Items]
Cost | $	$ 7,851	$ 0
Acres | a	3,279	0
Washington
Business Acquisition [Line Items]
Cost | $	$ 0	$ 1,483
Acres | a	0	481
New Zealand
Business Acquisition [Line Items]
Cost | $	$ 11,665	$ 21,376
Acres | a	3,833	7,546