Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 86,453	$ 10,938	$ 31,714
Adjustments to reconcile net income to net cash from operating activities:
Depreciation, depletion and amortization	29,912	34,190	38,105
Basis of real estate sold	6,827	8,011	7,012
Change in deferred taxes	15,364	1,853	(5,696)
Pension and other postretirement employee benefits	13,151	15,661	15,122
Equity-based compensation expense	4,722	4,390	4,758
Loss on sale of central Idaho timber and timberlands		48,522
Other, net	(1,872)	(1,198)	(2,046)
Change in:
Receivables	3,602	(3,712)	(3,864)
Inventories	2,490	(17,460)	(3,672)
Other assets	(15)	(473)	898
Accounts payable and accrued liabilities	11,591	7,232	267
Other liabilities	(4,291)	(4,537)	(8,584)
Funding of qualified pension plans	(5,275)	(1,300)
Net cash from operating activities	162,659	102,117	74,014
CASH FLOWS FROM INVESTING ACTIVITIES
Change in short-term investments			6,995
Transfer from company owned life insurance (COLI)	1,278	6,384	1,492
Transfer to COLI	(1,324)	(3,967)
Purchase of property, plant and equipment	(12,855)	(5,866)	(18,987)
Timberlands reforestation and roads	(15,207)	(13,422)	(13,745)
Acquisition of timber and timberlands	(22,043)	(1,244)	(10,230)
Net proceeds from sale of central Idaho timber and timberlands		111,460
Other, net	131	6	886
Net cash from investing activities	(50,020)	93,351	(33,589)
CASH FLOWS FROM FINANCING ACTIVITIES
Dividends to common stockholders	(61,931)	(60,842)	(61,017)
Repurchase of common stock		(5,956)
Revolving line of credit (repayment) borrowings		(30,000)	30,000
Repayment of long-term debt	(11,000)	(113,335)	(22,500)
Proceeds from issuance of long-term debt		93,235
Other, net	(1,835)	(3,911)	(3,000)
Net cash from financing activities	(74,766)	(120,809)	(56,517)
Change in cash and cash equivalents	37,873	74,659	(16,092)
Cash and cash equivalents at beginning of year	82,584	7,925	24,017
Cash and cash equivalents at end of year	120,457	82,584	7,925
Cash paid (received) during the year for:
Interest, net of amounts capitalized	26,125	28,051	29,676
Income taxes, net	$ 15,845	$ (8,081)	$ 1,576