CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Total revenues	[1]	$ 1,361,047	$ 1,322,575	$ 2,429,391	$ 2,371,817
Cost of revenues		962,683	926,056	1,801,760	1,773,575
Gross profit		398,364	396,519	627,631	598,242
Selling, administrative and general expenses		100,667	91,205	189,260	177,635
Gain (loss) on sale of property, plant & equipment and businesses		211	(258)	117,376	741
Other operating expense, net		(10,372)	(6,160)	(18,698)	(10,151)
Operating earnings		287,536	298,896	537,049	411,197
Other nonoperating income (expense), net		8,223	7,367	14,136	(1,969)
Interest expense, net		41,696	33,954	74,814	64,727
Earnings from continuing operations before income taxes		254,063	272,309	476,371	344,501
Income tax expense		57,283	61,352	117,922	73,546
Earnings from continuing operations		196,780	210,957	358,449	270,955
Loss on discontinued operations, net of tax		(1,436)	(1,041)	(2,491)	(781)
Net earnings		195,344	209,916	355,958	270,174
Other comprehensive income (loss), net of tax
Deferred loss on interest rate derivative		0	0	0	(14,679)
Amortization of prior interest rate derivative loss		360	194	716	988
Amortization of actuarial loss and prior service cost for benefit plans		1,235	1,695	2,470	3,390
Other comprehensive income (loss)		1,595	1,889	3,186	(10,301)
Comprehensive income		$ 196,939	$ 211,805	$ 359,144	$ 259,873
Basic earnings (loss) per share
Continuing operations		$ 1.48	$ 1.59	$ 2.70	$ 2.04
Discontinued operations		(0.01)	(0.01)	(0.02)	0.00
Net earnings		1.47	1.58	2.68	2.04
Diluted earnings (loss) per share
Continuing operations		1.47	1.58	2.69	2.03
Discontinued operations		(0.01)	0.00	(0.02)	0.00
Net earnings		$ 1.46	$ 1.58	$ 2.67	$ 2.03
Weighted-average common shares outstanding
Basic		132,781	132,552	132,765	132,560
Assuming dilution		133,507	133,115	133,455	133,154
Effective tax rate from continuing operations		22.50%	22.50%	24.80%	21.30%

[1] ¹ The geographic markets are defined by states/countries as follows: East market — Arkansas, Delaware, Illinois, Kentucky, Maryland, North Carolina, Pennsylvania, Tennessee, Virginia, and Washington D.C. Gulf Coast market — Alabama, Florida, Georgia, Louisiana, Mexico, Mississippi, Oklahoma, South Carolina and Texas West market — Arizona, California and New Mexico