Segment Information (Summary of Information by Business Segment) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Adjusted EBITDDA		$ 175,170	$ 274,984	$ 420,732	$ 469,970
Interest expense, net	[1]	(7,419)	(8,199)	(10,313)	(11,773)
Depreciation, depletion and amortization		(20,007)	(17,029)	(39,509)	(35,025)
Basis of real estate sold		(7,325)	(7,213)	(18,179)	(16,036)
Gain on fire damage		9,868	0	9,592	0
Pension settlement charge		0	0	(14,165)	0
Non-operating pension and other postretirement employee benefits		(1,809)	(3,271)	(3,738)	(6,685)
Gain (loss) on disposal of fixed assets		13	(527)	16	(561)
Income before income taxes		148,491	238,745	344,436	399,890
Bond discounts and deferred loan fees	[1]	372	403	744	806
Total depreciation, depletion and amortization		20,379	17,432	40,253	35,831
Operating Segments [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization		20,007	17,029	39,509	35,025
Operating Segments [Member] | Timberlands [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		57,890	77,259	134,324	145,117
Depreciation, depletion and amortization		11,563	10,482	23,724	21,899
Operating Segments [Member] | Wood Products [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		107,256	204,533	257,207	330,088
Depreciation, depletion and amortization		8,136	6,179	15,157	12,382
Operating Segments [Member] | Real Estate Segment [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		21,816	11,788	51,940	28,381
Depreciation, depletion and amortization		173	160	343	315
Basis of real estate sold		(7,328)	(7,219)	(18,188)	(16,048)
Corporate [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		(13,912)	(12,822)	(23,496)	(23,532)
Depreciation, depletion and amortization		135	208	285	429
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		2,120	(5,774)	757	(10,084)
Basis of real estate sold		$ 3	$ 6	$ 9	$ 12

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