Timberland Acquisitions - Narrative (Details) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) a acquisition	Dec. 31, 2017 USD ($) a acquisition shares	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Timberlands acquired (acres)	29,857	109,533
Payments to acquire timberlands | $	$ 57,608	$ 242,910	$ 366,481
Florida, Georgia, And Texas
Business Acquisition [Line Items]
Timberlands acquired (acres)	26,000
Payments to acquire timberlands | $	$ 45,900
Georgia and Washington
Business Acquisition [Line Items]
Number of acquisitions | acquisition	5
Timberlands acquired (acres)	7,000,000
Payments to acquire timberlands | $	$ 7,200
Florida, Georgia, and South Carolina
Business Acquisition [Line Items]
Timberlands acquired (acres)		95,100
Timberlands acquired, leased lands (acres)		11,000
Shares sold (shares) | shares		5,750
Payments to acquire timberlands | $		$ 214,300
New Zealand
Business Acquisition [Line Items]
Number of acquisitions | acquisition	2	2
Timberlands acquired (acres)	3,833	7,546
Payments to acquire timberlands | $	$ 11,665	$ 21,376