Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES
Net income				$ 384,678	$ 66,813
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization		$ 21,534	$ 20,594	57,365	57,809
Basis of real estate sold		6,697	5,249	22,733	14,440
Change in deferred taxes				3,221	(14,387)
Pension and other postretirement employee benefits				16,595	17,750
Pension settlement charge					42,988
Equity-based compensation expense				6,345	5,928
Net gain on insurance recoveries		(4,394)		(4,394)
Other, net				633	(544)
Change in working capital and operating-related activities, net				(20,082)	12,706
Real estate development expenditures				(6,434)	(4,200)
Funding of pension and other postretirement employee benefits				(7,418)	(8,458)
Net cash provided by operating activities				453,242	190,845
CASH FLOWS FROM INVESTING ACTIVITIES
Property, plant and equipment additions				(26,291)	(14,666)
Timberlands reforestation and roads				(12,236)	(12,345)
Acquisition of timber and timberlands				(2,450)	(4,738)
Proceeds from insurance recoveries - property, plant & equipment				13,250
Other, net				993	3,484
Net cash used in investing activities				(26,734)	(28,265)
CASH FLOWS FROM FINANCING ACTIVITIES
Distributions to common stockholders				(82,462)	(80,434)
Repurchase of common stock					(15,364)
Other, net				(3,619)	(1,032)
Net cash used in financing activities				(86,081)	(96,830)
Change in cash, cash equivalents and restricted cash				340,427	65,750
Cash, cash equivalents and restricted cash at beginning of period				252,340	84,254
Cash, cash equivalents and restricted cash at end of period		592,767	150,004	592,767	150,004
NONCASH INVESTING AND FINANCING ACTIVITIES
Accrued property, plant and equipment additions				2,695	3,785
Accrued timberlands reforestation and roads				1,590	1,536
Cash and cash equivalents		$ 592,767	148,919	$ 592,767	148,919
Restricted cash included in other long-term assets	[1]		$ 1,085		$ 1,085
Restricted Cash, Asset, Statement of Financial Position [Extensible List]		us-gaap:OtherAssetsMember	us-gaap:OtherAssetsMember	us-gaap:OtherAssetsMember	us-gaap:OtherAssetsMember
Total cash, cash equivalents, and restricted cash		$ 592,767	$ 150,004	$ 592,767	$ 150,004

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