Segment Information (Summary Of Information By Business Segment) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Segment Revenues		$ 289,199	$ 190,441	$ 757,329	$ 503,351
Adjusted EBITDDA		101,810	62,235	260,750	145,232
Basis of real estate sold		4,248	579	10,673	6,351
Depreciation, depletion and amortization		18,836	8,196	51,982	20,796
Interest expense, net		(10,109)	(7,336)	(25,125)	(19,654)
Non-operating pension and other postretirement employee benefits		(1,942)	(1,596)	(5,707)	(4,788)
Gain (loss) on fixed assets		(12)		(11)	(16)
Lumber price swap	[1]		(3,066)		199
Environmental charges for Avery Landing			(4,978)		(4,978)
Deltic merger-related costs	[2]	(972)	(27)	(21,245)	(27)
Income before income taxes		65,691	36,457	144,158	88,821
Bond discounts and deferred loan fees	[3]	609	369	1,703	1,112
Depreciation, depletion and amortization		19,445	8,565	53,685	21,908
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues		321,679	214,474	851,082	554,927
Depreciation, depletion and amortization		18,836	8,196	51,982	20,796
Operating Segments [Member] | Resource [Member]
Segment Reporting Information [Line Items]
Segment Revenues		111,421	94,705	280,438	202,397
Adjusted EBITDDA		58,680	48,034	140,068	91,200
Depreciation, depletion and amortization		12,730	6,207	35,974	14,865
Operating Segments [Member] | Wood Products [Member]
Segment Reporting Information [Line Items]
Segment Revenues		199,025	116,487	532,425	326,608
Adjusted EBITDDA		46,446	24,395	126,962	58,660
Depreciation, depletion and amortization		5,827	1,821	15,250	5,487
Operating Segments [Member] | Real Estate [Member]
Segment Reporting Information [Line Items]
Segment Revenues		11,233	3,282	38,219	25,922
Adjusted EBITDDA		7,467	2,094	27,769	22,333
Basis of real estate sold		4,267	618	10,886	6,474
Depreciation, depletion and amortization		81		198	1
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Segment Revenues	[4]	(32,480)	(24,033)	(93,753)	(51,576)
Adjusted EBITDDA		(1,794)	(3,180)	(5,080)	(1,152)
Basis of real estate sold		(19)	(39)	(213)	(123)
Corporate [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDDA		(8,989)	(9,108)	(28,969)	(25,809)
Depreciation, depletion and amortization		$ 198	$ 168	560	$ 443
Costs of Goods Sold [Member]
Segment Reporting Information [Line Items]
Inventory purchase price adjustment in cost of goods sold	[5]			$ (1,849)

[1] Includes change in unrealized (gain) loss and $1 million in cash settlements.

[2] For integration and restructuring costs related to the merger with Deltic see Note 13: Merger, Integration and Other Costs.

[3] Bond discounts and deferred loan fees are reported within interest expense, net on the Condensed Consolidated Statement of Income.

[4] Intersegment revenues are based on prevailing market prices of logs sold by our Resource segment to the Wood Products segment.

[5] The effect on cost of goods sold for fair value adjustments to the carrying amounts of inventory acquired in business combinations.