REVENUE (Disaggregation of Revenue by Contract Type) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total Timber Sales	$ 245,592	$ 200,719	$ 448,559	$ 394,916
Stumpage Pay-as-Cut
Disaggregation of Revenue [Line Items]
Total Timber Sales	19,855	18,249	42,364	38,352
Stumpage Lump Sum
Disaggregation of Revenue [Line Items]
Total Timber Sales	4,861	2,247	11,785	7,623
Stumpage Agreed Volume
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	54	0	1,234
Total Stumpage
Disaggregation of Revenue [Line Items]
Total Timber Sales	24,716	20,550	54,149	47,209
Total Delivered
Disaggregation of Revenue [Line Items]
Total Timber Sales	158,826	124,238	287,689	229,803
Total Delivered | Domestic
Disaggregation of Revenue [Line Items]
Total Timber Sales	69,054	51,593	128,851	102,293
Total Delivered | Export
Disaggregation of Revenue [Line Items]
Total Timber Sales	89,772	72,645	158,838	127,510
Timber
Disaggregation of Revenue [Line Items]
Total Timber Sales	183,542	144,788	341,838	277,012
Southern Timber | Stumpage Pay-as-Cut
Disaggregation of Revenue [Line Items]
Total Timber Sales	19,855	18,249	42,364	38,352
Southern Timber | Stumpage Lump Sum
Disaggregation of Revenue [Line Items]
Total Timber Sales	256	2,247	2,074	5,043
Southern Timber | Stumpage Agreed Volume
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
Southern Timber | Total Stumpage
Disaggregation of Revenue [Line Items]
Total Timber Sales	20,111	20,496	44,438	43,395
Southern Timber | Total Delivered
Disaggregation of Revenue [Line Items]
Total Timber Sales	17,179	10,281	30,990	20,097
Southern Timber | Total Delivered | Domestic
Disaggregation of Revenue [Line Items]
Total Timber Sales	15,166	10,281	28,543	20,097
Southern Timber | Total Delivered | Export
Disaggregation of Revenue [Line Items]
Total Timber Sales	2,013	0	2,447	0
Pacific Northwest Timber | Stumpage Pay-as-Cut
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
Pacific Northwest Timber | Stumpage Lump Sum
Disaggregation of Revenue [Line Items]
Total Timber Sales	4,605	0	9,711	2,580
Pacific Northwest Timber | Stumpage Agreed Volume
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	54	0	1,234
Pacific Northwest Timber | Total Stumpage
Disaggregation of Revenue [Line Items]
Total Timber Sales	4,605	54	9,711	3,814
Pacific Northwest Timber | Total Delivered
Disaggregation of Revenue [Line Items]
Total Timber Sales	26,674	19,397	52,054	40,429
Pacific Northwest Timber | Total Delivered | Domestic
Disaggregation of Revenue [Line Items]
Total Timber Sales	26,674	19,397	52,054	40,429
Pacific Northwest Timber | Total Delivered | Export
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
New Zealand Timber | Stumpage Pay-as-Cut
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
New Zealand Timber | Stumpage Lump Sum
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
New Zealand Timber | Stumpage Agreed Volume
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
New Zealand Timber | Total Stumpage
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
New Zealand Timber | Total Delivered
Disaggregation of Revenue [Line Items]
Total Timber Sales	69,007	52,853	119,596	93,593
New Zealand Timber | Total Delivered | Domestic
Disaggregation of Revenue [Line Items]
Total Timber Sales	25,647	20,598	45,750	39,443
New Zealand Timber | Total Delivered | Export
Disaggregation of Revenue [Line Items]
Total Timber Sales	43,360	32,255	73,846	54,150
Trading | Stumpage Pay-as-Cut
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
Trading | Stumpage Lump Sum
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
Trading | Stumpage Agreed Volume
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
Trading | Total Stumpage
Disaggregation of Revenue [Line Items]
Total Timber Sales	0	0	0	0
Trading | Total Delivered
Disaggregation of Revenue [Line Items]
Total Timber Sales	45,966	41,707	85,049	75,684
Trading | Total Delivered | Domestic
Disaggregation of Revenue [Line Items]
Total Timber Sales	1,567	1,317	2,504	2,324
Trading | Total Delivered | Export
Disaggregation of Revenue [Line Items]
Total Timber Sales	$ 44,399	$ 40,390	$ 82,545	$ 73,360