Revenue Recognition (Summary of Revenues by Major Product) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue Recognition [Line Items]
Revenues		$ 268,233	$ 163,229	$ 468,130	$ 312,910
Operating Segments [Member]
Revenue Recognition [Line Items]
Revenues		302,527	178,589	529,403	340,453
Intersegment Eliminations [Member]
Revenue Recognition [Line Items]
Revenues	[1]	(34,294)	(15,360)	(61,273)	(27,543)
Resource [Member] | Operating Segments [Member]
Revenue Recognition [Line Items]
Revenues		92,511	55,924	169,017	107,692
Resource [Member] | Operating Segments [Member] | Northern Region [Member]
Revenue Recognition [Line Items]
Revenues		51,235	40,002	102,894	74,437
Resource [Member] | Operating Segments [Member] | Northern Region [Member] | Sawlogs [Member]
Revenue Recognition [Line Items]
Revenues		49,627	38,258	99,211	70,344
Resource [Member] | Operating Segments [Member] | Northern Region [Member] | Pulpwood [Member]
Revenue Recognition [Line Items]
Revenues		1,299	1,491	3,079	3,445
Resource [Member] | Operating Segments [Member] | Northern Region [Member] | Stumpage [Member]
Revenue Recognition [Line Items]
Revenues		57		136	142
Resource [Member] | Operating Segments [Member] | Northern Region [Member] | Other [Member]
Revenue Recognition [Line Items]
Revenues		252	253	468	506
Resource [Member] | Operating Segments [Member] | Southern Region [Member]
Revenue Recognition [Line Items]
Revenues		41,276	15,922	66,123	33,255
Resource [Member] | Operating Segments [Member] | Southern Region [Member] | Sawlogs [Member]
Revenue Recognition [Line Items]
Revenues		25,190	7,544	39,220	16,233
Resource [Member] | Operating Segments [Member] | Southern Region [Member] | Pulpwood [Member]
Revenue Recognition [Line Items]
Revenues		13,468	7,312	22,438	14,954
Resource [Member] | Operating Segments [Member] | Southern Region [Member] | Stumpage [Member]
Revenue Recognition [Line Items]
Revenues		1,062	148	1,453	230
Resource [Member] | Operating Segments [Member] | Southern Region [Member] | Other [Member]
Revenue Recognition [Line Items]
Revenues		1,556	918	3,012	1,838
Wood Products [Member] | Operating Segments [Member]
Revenue Recognition [Line Items]
Revenues		193,585	114,529	333,400	210,121
Wood Products [Member] | Operating Segments [Member] | Lumber [Member]
Revenue Recognition [Line Items]
Revenues		133,788	81,702	228,781	146,574
Wood Products [Member] | Operating Segments [Member] | Panels [Member]
Revenue Recognition [Line Items]
Revenues		41,239	19,283	70,130	36,978
Wood Products [Member] | Operating Segments [Member] | Residuals [Member]
Revenue Recognition [Line Items]
Revenues		18,558	13,544	34,489	26,569
Real Estate Segment [Member] | Operating Segments [Member]
Revenue Recognition [Line Items]
Revenues		16,431	8,136	26,986	22,640
Real Estate Segment [Member] | Operating Segments [Member] | Rural Real Estate [Member]
Revenue Recognition [Line Items]
Revenues		12,669	$ 8,136	21,502	$ 22,640
Real Estate Segment [Member] | Operating Segments [Member] | Development Real Estate [Member]
Revenue Recognition [Line Items]
Revenues		1,743		2,962
Real Estate Segment [Member] | Operating Segments [Member] | Other [Member]
Revenue Recognition [Line Items]
Revenues		$ 2,019		$ 2,522

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