Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Revenues		$ 827,098		$ 974,579		$ 678,595
Costs and expenses:
Cost of goods sold		682,066		707,645		469,393
Selling, general and administrative expenses		57,925		59,861		49,996
Gain on sale of facility		(9,176)
Deltic merger-related costs	[1]			22,119		3,409
Environmental charges for Avery Landing						4,978
Gain on lumber price swap						(1,088)
Total costs and expenses		730,815		789,625		526,688
Operating income		96,283		184,954		151,907
Interest expense, net	[2]	(30,361)		(35,227)		(27,049)
Loss on extinguishment of debt		(5,512)
Non-operating pension and other postretirement employee benefit costs		(3,739)		(7,648)		(6,384)
Income before income taxes		56,671		142,079		118,474
Income tax provision		(1,010)		(19,199)		(32,021)
Net income		$ 55,661		$ 122,880		$ 86,453
Net income per share:
Basic (in dollars per share)		$ 0.82	[3]	$ 2.03	[3]	$ 2.12
Diluted (in dollars per share)		0.82	[3]	1.99	[3]	2.10
Dividends/Special distribution per share		$ 1.60		$ 1.60		$ 1.53
Weighted-average shares outstanding (in thousands)
Basic (in shares)		67,608		60,534		40,824
Diluted (in shares)		67,743		61,814		41,227
Deltic [Member]
Costs and expenses:
Deltic merger-related costs				$ 22,100		$ 3,400
Net income per share:
Dividends/Special distribution per share				$ 3.54

[1] For integration and restructuring costs related to the merger with Deltic see Note 2: Merger with Deltic.

[2] Bond discounts and deferred loan fees are reported within interest expense on the Consolidated Statements of Income

[3] Per share amounts are computed independently for each of the quarters presented. Therefore, the sum of the quarterly per share amounts may not equal the total computed for the year.