CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities
Net earnings	$ 160,614	$ 60,258
Adjustments to reconcile net earnings to net cash provided by operating activities
Depreciation, depletion, accretion and amortization	100,368	95,480
Noncash operating lease expense	10,528	8,851
Net gain on sale of property, plant & equipment and businesses	(117,165)	(999)
Contributions to pension plans	(2,124)	(2,144)
Share-based compensation expense	7,869	6,716
Deferred tax expense	26,949	19,671
Changes in assets and liabilities before initial effects of business acquisitions and dispositions	(16,992)	(99,597)
Other, net	(785)	(5,761)
Net cash provided by operating activities	169,262	82,475
Investing Activities
Purchases of property, plant & equipment	(100,650)	(142,650)
Proceeds from sale of property, plant & equipment	186,497	2,536
Other, net	25	9,872
Net cash provided by (used for) investing activities	85,872	(130,242)
Financing Activities
Payment of current maturities and long-term debt	(500,006)	(6)
Settlements of interest rate derivatives	0	(19,863)
Purchases of common stock	0	(26,132)
Dividends paid	(49,085)	(45,100)
Share-based compensation, shares withheld for taxes	(12,086)	(15,064)
Other, net	(1,031)	(301)
Net cash used for financing activities	(562,208)	(106,466)
Net decrease in cash and cash equivalents and restricted cash	(307,074)	(154,233)
Cash and cash equivalents and restricted cash at beginning of year	1,198,013	274,506
Cash and cash equivalents and restricted cash at end of period	$ 890,939	$ 120,273