CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Total revenues	$ 1,008,140,000	$ 1,038,460,000	$ 2,719,693,000	$ 2,564,896,000
Cost of revenues	703,931,000	747,170,000	1,958,581,000	1,961,292,000
Gross profit	304,209,000	291,290,000	761,112,000	603,604,000
Selling, administrative and general expenses	76,311,000	71,390,000	235,460,000	207,350,000
Gain on sale of property, plant & equipment and businesses	2,023,000	799,000	2,934,000	7,423,000
Business interruption claims recovery	690,000	0	11,652,000	0
Impairment of long-lived assets	0	0	(10,506,000)	(5,190,000)
Restructuring charges	0	(448,000)	(320,000)	(4,546,000)
Other operating expense, net	(3,535,000)	(8,045,000)	(23,629,000)	(17,201,000)
Operating earnings	227,076,000	212,206,000	505,783,000	376,740,000
Other nonoperating income (expense), net	990,000	(2,818,000)	325,000	(2,277,000)
Interest expense, net	33,126,000	37,800,000	100,192,000	183,931,000
Earnings from continuing operations before income taxes	194,940,000	171,588,000	405,916,000	190,532,000
Provision for income taxes	52,062,000	45,386,000	116,026,000	51,177,000
Earnings from continuing operations	142,878,000	126,202,000	289,890,000	139,355,000
Loss on discontinued operations, net of tax	(3,113,000)	(2,397,000)	(7,451,000)	(7,066,000)
Net earnings	139,765,000	123,805,000	282,439,000	132,289,000
Other comprehensive income, net of tax
Reclassification adjustment for cash flow hedges	307,000	282,000	902,000	5,607,000
Amortization of actuarial loss and prior service cost for benefit plans	20,000	3,883,000	61,000	9,261,000
Other comprehensive income	327,000	4,165,000	963,000	14,868,000
Comprehensive income	$ 140,092,000	$ 127,970,000	$ 283,402,000	$ 147,157,000
Basic earnings (loss) per share
Continuing operations	$ 1.07	$ 0.95	$ 2.17	$ 1.05
Discontinued operations	(0.02)	(0.02)	(0.05)	(0.06)
Net earnings	1.05	0.93	2.12	0.99
Diluted earnings (loss) per share
Continuing operations	1.06	0.93	2.14	1.03
Discontinued operations	(0.02)	(0.02)	(0.05)	(0.05)
Net earnings	$ 1.04	$ 0.91	$ 2.09	$ 0.98
Weighted-average common shares outstanding
Basic	133,019	133,474	133,418	133,082
Assuming dilution	135,033	135,558	135,192	134,942
Cash dividends per share of common stock	$ 0.20	$ 0.10	$ 0.60	$ 0.30
Depreciation, depletion, accretion and amortization	$ 72,049,000	$ 69,662,000	$ 213,362,000	$ 204,770,000
Effective tax rate from continuing operations	26.70%	26.50%	28.60%	26.90%