Condensed Consolidated Statements of Cash Flows (Unaudited) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)		Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)			$ 319,011	$ (14,194)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	$ 18,171		35,831	37,215
Basis of real estate sold	2,693		16,036	9,191
Change in deferred taxes			562	(13,849)
Pension and other postretirement employee benefits			11,111	11,833
Pension settlement charge				42,988
Equity-based compensation expense			4,070	3,865
Other, net			(295)	(177)
Change in working capital and operating-related activities, net			(37,154)	16,397
Real estate development expenditures			(3,999)	(2,487)
Funding of pension and other postretirement employee benefits			(3,833)	(2,839)
Net cash provided by operating activities			341,340	87,943
CASH FLOWS FROM INVESTING ACTIVITIES
Property, plant and equipment additions			(15,943)	(10,295)
Timberlands reforestation and roads			(7,954)	(7,776)
Acquisition of timber and timberlands			(2,192)	(4,730)
Proceeds on sale of facility				1,000
Other, net			635	2,113
Net cash used in investing activities			(25,454)	(19,688)
CASH FLOWS FROM FINANCING ACTIVITIES
Distributions to common stockholders			(54,973)	(53,685)
Repurchase of common stock				(15,364)
Other, net			(1,223)	(526)
Net cash used in financing activities			(56,196)	(69,575)
Change in cash, cash equivalents and restricted cash			259,690	(1,320)
Cash, cash equivalents and restricted cash at beginning of period			252,340	84,254
Cash, cash equivalents and restricted cash at end of period	82,934		512,030	82,934
NONCASH INVESTING AND FINANCING ACTIVITIES
Accrued property, plant and equipment additions			1,474	706
Accrued timberlands reforestation and roads			1,170	462
Cash and cash equivalents	80,987		$ 512,030	80,987
Restricted cash included in other long-term assets	$ 1,947	[1]		$ 1,947	[1]
Restricted Cash, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsMember		us-gaap:OtherAssetsMember	us-gaap:OtherAssetsMember

[1] Amounts included in restricted cash represent proceeds held by a qualified intermediary that are intended to be reinvested in timber and timberlands.