Segment Information (Summary of Information by Business Segment) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Adjusted EBITDDA		$ 194,986	$ 47,571
Interest expense, net	[1],[2]	(3,574)	(3,698)
Depreciation, depletion and amortization		(17,996)	(18,638)
Basis of real estate sold		8,823	6,498
Pension settlement charge			(42,988)
Non-operating pension and other postretirement employee benefits		(3,414)	(3,635)
(Loss) gain on disposal of fixed assets		(34)	192
Income (loss) before income taxes		161,145	(27,694)
Bond discounts and deferred loan fees	[1]	403	406
Total depreciation, depletion and amortization		18,399	19,044
Operating Segments [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization		17,996	18,638
Operating Segments [Member] | Timberlands [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		67,858	34,982
Depreciation, depletion and amortization		11,417	12,591
Operating Segments [Member] | Wood Products [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		125,555	13,229
Depreciation, depletion and amortization		6,203	5,630
Operating Segments [Member] | Real Estate Segment [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		16,593	7,340
Depreciation, depletion and amortization		155	160
Basis of real estate sold		8,829	6,504
Corporate [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		(10,710)	(8,672)
Depreciation, depletion and amortization		221	257
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		(4,310)	692
Basis of real estate sold		$ (6)	$ (6)

[1] Bond discounts and deferred loan fees are reported within interest expense, net on the Condensed Consolidated Statements of Operations.

[2] Realized losses on interest rate contracts consist of net cash received or paid and interest accruals on the interest rate swaps during the periods. Net cash received or paid is included in the supplemental cash flow information within interest, net of amounts capitalized in the Condensed Consolidated Statements of Cash Flows.