CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Total revenues	$ 956,825,000	$ 895,143,000	$ 1,711,552,000	$ 1,526,436,000
Cost of revenues	664,641,000	660,694,000	1,254,649,000	1,214,122,000
Gross profit	292,184,000	234,449,000	456,903,000	312,314,000
Selling, administrative and general expenses	82,681,000	69,197,000	159,149,000	135,960,000
Gain on sale of property, plant & equipment and businesses	356,000	249,000	911,000	6,624,000
Business interruption claims recovery	10,962,000	0	10,962,000	0
Impairment of long-lived assets	(860,000)	(5,190,000)	(10,506,000)	(5,190,000)
Restructuring charges	0	(1,280,000)	(320,000)	(4,098,000)
Other operating expense, net	(6,175,000)	(5,255,000)	(20,094,000)	(9,156,000)
Operating earnings	213,786,000	153,776,000	278,707,000	164,534,000
Other nonoperating income (expense), net	29,000	(439,000)	(666,000)	542,000
Interest expense, net	(33,333,000)	(83,651,000)	(67,065,000)	(146,132,000)
Earnings from continuing operations before income taxes	180,482,000	69,686,000	210,976,000	18,944,000
Provision for income taxes	54,200,000	19,867,000	63,964,000	5,791,000
Earnings from continuing operations	126,282,000	49,819,000	147,012,000	13,153,000
Loss on discontinued operations, net of tax	(2,532,000)	(1,657,000)	(4,338,000)	(4,669,000)
Net earnings	123,750,000	48,162,000	142,674,000	8,484,000
Other comprehensive income, net of tax
Reclassification adjustment for cash flow hedges	301,000	3,077,000	595,000	5,325,000
Amortization of actuarial loss and prior service cost for benefit plans	20,000	2,697,000	40,000	5,378,000
Other comprehensive income	321,000	5,774,000	635,000	10,703,000
Comprehensive income	$ 124,071,000	$ 53,936,000	$ 143,309,000	$ 19,187,000
Basic earnings (loss) per share
Continuing operations	$ 0.95	$ 0.37	$ 1.10	$ 0.10
Discontinued operations	(0.02)	(0.01)	(0.03)	(0.04)
Net earnings	0.93	0.36	1.07	0.06
Diluted earnings (loss) per share
Continuing operations	0.93	0.37	1.09	0.10
Discontinued operations	(0.02)	(0.01)	(0.04)	(0.04)
Net earnings	$ 0.91	$ 0.36	$ 1.05	$ 0.06
Weighted-average common shares outstanding
Basic	133,419	133,103	133,619	132,882
Assuming dilution	135,395	135,234	135,370	134,689
Cash dividends per share of common stock	$ 0.20	$ 0.10	$ 0.40	$ 0.20
Depreciation, depletion, accretion and amortization	$ 71,908,000	$ 68,384,000	$ 141,314,000	$ 135,108,000
Effective tax rate from continuing operations	30.00%	28.50%	30.30%	30.60%