CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Total revenues	[1]	$ 4,929,103	$ 4,382,869	$ 3,890,296
Cost of revenues		3,673,202	3,281,924	2,896,783
Gross profit		1,255,901	1,100,945	993,513
Selling, administrative and general expenses		370,548	333,371	324,972
Gain on sale of property, plant & equipment and businesses		23,752	14,944	17,827
Other operating expense, net		(31,647)	(34,805)	(47,324)
Operating earnings		877,458	747,713	639,044
Other nonoperating income, net		9,243	13,000	13,357
Interest income		1,155	554	4,437
Interest expense		130,155	137,977	295,522
Earnings from continuing operations before income taxes		757,701	623,290	361,316
Income tax expense (benefit)
Current		58,941	40,516	354
Deferred		76,257	64,933	(232,429)
Total income tax expense (benefit)		135,198	105,449	(232,075)
Earnings from continuing operations		622,503	517,841	593,391
Earnings (loss) on discontinued operations, net of income taxes		(4,841)	(2,036)	7,794
Net earnings		617,662	515,805	601,185
Other comprehensive income (loss), net of tax
Deferred gain on interest rate derivative		0	2,496	0
Amortization of prior interest rate derivative loss		227	226	1,862
Adjustment for funded status of benefit plans		(26,892)	(207)	(14,106)
Amortization of actuarial loss and prior service cost for benefit plans		1,142	4,365	2,154
Other comprehensive income (loss)		(25,523)	6,880	(10,090)
Comprehensive income		$ 592,139	$ 522,685	$ 591,095
Basic earnings (loss) per share
Continuing operations		$ 4.71	$ 3.91	$ 4.48
Discontinued operations		(0.04)	(0.01)	0.06
Net earnings		4.67	3.90	4.54
Diluted earnings (loss) per share
Continuing operations		4.67	3.87	4.40
Discontinued operations		(0.04)	(0.02)	0.06
Net earnings		$ 4.63	$ 3.85	$ 4.46
Weighted-average common shares outstanding
Basic		132,300	132,393	132,513
Assuming dilution		133,385	133,926	134,878

[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, Texas and the Bahamas West market — Arizona, California and New Mexico