CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Total revenues	[1]	$ 1,309,890	$ 1,418,758	$ 3,681,707	$ 3,742,951
Cost of revenues		929,392	1,018,115	2,702,967	2,780,131
Gross profit		380,498	400,643	978,740	962,820
Selling, administrative and general expenses		83,511	88,789	261,146	274,747
Gain on sale of property, plant & equipment and businesses		1,576	234	2,317	10,982
Other operating expense, net		(10,459)	(8,712)	(20,610)	(15,173)
Operating earnings		288,104	303,376	699,301	683,882
Other nonoperating income, net		5,787	359	3,818	5,954
Interest expense, net		35,782	32,197	100,509	98,165
Earnings from continuing operations before income taxes		258,109	271,538	602,610	591,671
Income tax expense		56,984	53,472	130,530	111,764
Earnings from continuing operations		201,125	218,066	472,080	479,907
Loss on discontinued operations, net of tax		(1,337)	(2,353)	(2,118)	(3,338)
Net earnings		199,788	215,713	469,962	476,569
Other comprehensive income (loss), net of tax
Deferred loss on interest rate derivative		0	0	(14,679)	0
Amortization of prior interest rate derivative loss		350	57	1,338	169
Amortization of actuarial loss and prior service cost for benefit plans		1,695	286	5,085	856
Other comprehensive income (loss)		2,045	343	(8,256)	1,025
Comprehensive income		$ 201,833	$ 216,056	$ 461,706	$ 477,594
Basic earnings (loss) per share
Continuing operations		$ 1.52	$ 1.65	$ 3.56	$ 3.63
Discontinued operations		(0.01)	(0.02)	(0.01)	(0.03)
Net earnings		1.51	1.63	3.55	3.60
Diluted earnings (loss) per share
Continuing operations		1.51	1.63	3.54	3.60
Discontinued operations		(0.01)	(0.01)	(0.01)	(0.02)
Net earnings		$ 1.50	$ 1.62	$ 3.53	$ 3.58
Weighted-average common shares outstanding
Basic		132,573	132,414	132,564	132,244
Assuming dilution		133,268	133,375	133,192	133,273
Depreciation, depletion, accretion and amortization		$ 100,962	$ 96,247	$ 295,912	$ 278,925
Effective tax rate from continuing operations		22.10%	19.70%	21.70%	18.90%

[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