Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net income	$ 31,763	$ 52,131
Income from discontinued operations, net of tax	30	15
Income from continuing operations	31,733	52,116
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	80,121	73,723
Deferred income taxes	(6,466)	9,843
Provision for credit losses	1,735	(317)
Amortization of debt issuance costs	341	332
Employee stock-based compensation costs	2,689	2,574
Pension & postretirement benefit plan net periodic benefit credit	(1,491)	(1,226)
Unrealized losses on investments	5,147	529
Gains on sales of assets	(3,136)	(2,919)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(5,723)	89,724
Inventories	(44,080)	(25,613)
Other current assets	34,491	(46,837)
Accounts payable	2,980	(41,965)
Other current liabilities	13,086	(13,977)
Pension & postretirement benefit plan contributions	(149)	(119)
Other noncurrent changes	1,139	(223)
Net cash provided by continuing operations	112,417	95,645
Net cash used in discontinued operations	(7)	(25)
Net cash provided by operating activities	112,410	95,620
Investing activities:
Capital expenditures	(150,288)	(111,091)
Acquisitions, net of cash acquired	(524)	(1,023)
Net proceeds from sale or disposition of property and other	4,586	9,035
Investments	(4,442)	(3,248)
Net cash used in investing activities	(150,668)	(106,327)
Financing activities:
Issuance of short-term borrowings	100,000	50,000
Repayment of short-term borrowings	0	(50,000)
Issuance of long-term debt	150,000	93,298
Repayment of long-term debt	(143,622)	(53,301)
Debt issuance costs	(718)	(3)
Net proceeds from issuance of common stock	(127)	19,699
Dividends paid	(44,229)	(42,611)
Repurchase of common stock	(7,399)	(6,701)
Tax withholding on stock-based compensation	(4,904)	(4,127)
Net cash provided by financing activities	49,001	6,254
Increase (decrease) in cash and cash equivalents	10,743	(4,453)
Cash and cash equivalents -- beginning of year	54,161	59,547
Cash and cash equivalents -- end of period	$ 64,904	$ 55,094