CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Total revenues	$ 787,328	$ 754,728
Cost of revenues	627,349	590,010
Gross profit	159,979	164,718
Selling, administrative and general expenses	82,120	76,468
Gain on sale of property, plant & equipment and businesses	369	555
Impairment of long-lived assets	0	(9,646)
Other operating expense, net	(5,828)	(14,238)
Operating earnings	72,400	64,921
Other nonoperating income (expense), net	2,024	(694)
Interest expense, net	34,076	33,732
Earnings from continuing operations before income taxes	40,348	30,495
Income tax expense (benefit)	(3,175)	(11,470)
Earnings from continuing operations	43,523	41,965
Earnings (loss) on discontinued operations, net of tax (Note 2)	1,398	(1,807)
Net earnings	44,921	40,158
Other comprehensive income, net of tax
Reclassification adjustment for cash flow hedges	320	294
Amortization of actuarial loss and prior service cost for benefit plans	427	20
Other comprehensive income	747	314
Comprehensive income	$ 45,668	$ 40,472
Basic earnings (loss) per share
Continuing operations	$ 0.33	$ 0.31
Discontinued operations	0.01	(0.01)
Net earnings	0.34	0.30
Diluted earnings (loss) per share
Continuing operations	0.32	0.31
Discontinued operations	0.01	(0.01)
Net earnings	$ 0.33	$ 0.30
Weighted-average common shares outstanding
Basic	132,636	133,821
Assuming dilution	134,968	136,100
Cash dividends per share of common stock	$ 0.25	$ 0.20
Depreciation, depletion, accretion and amortization	$ 71,563	$ 69,406
Effective tax rate from continuing operations	(7.90%)	(37.60%)