CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Activities
Net earnings	$ 132,289,000	$ 166,902,000
Adjustments to reconcile net earnings to net cash provided by operating activities
Depreciation, depletion, accretion and amortization	204,770,000	208,858,000
Net gain on sale of property, plant & equipment and businesses	(7,423,000)	(238,527,000)
Contributions to pension plans	(11,337,000)	(4,115,000)
Share-based compensation	14,020,000	18,425,000
Excess tax benefits from share-based compensation	(16,950,000)	(3,375,000)
Deferred tax provision (benefit)	(7,640,000)	13,158,000
Cost of debt purchase	67,075,000	72,949,000
Changes in assets and liabilities before initial effects of business acquisitions and dispositions	(79,000,000)	(89,888,000)
Other, net	(14,467,000)	5,339,000
Net cash provided by operating activities	281,337,000	149,726,000
Investing Activities
Purchases of property, plant & equipment	(214,815,000)	(169,220,000)
Proceeds from sale of property, plant & equipment	4,464,000	21,320,000
Proceeds from sale of businesses, net of transaction costs	0	719,089,000
Payment for businesses acquired, net of acquired cash	(20,801,000)	(268,604,000)
Other, net	(301,000)	0
Net cash provided by (used for) investing activities	(231,453,000)	302,585,000
Financing Activities
Proceeds from line of credit	291,000,000	70,000,000
Payment of current maturities, long-term debt and line of credit	(751,056,000)	(649,711,000)
Proceeds from issuance of long-term debt	400,000,000	0
Debt and line of credit issuance costs	(7,382,000)	0
Proceeds from issuance of common stock	0	30,620,000
Dividends paid	(39,878,000)	(20,973,000)
Proceeds from exercise of stock options	67,888,000	12,513,000
Excess tax benefits from share-based compensation	16,950,000	3,375,000
Other, net	2,000	(5,000)
Net cash used for financing activities	(22,476,000)	(554,181,000)
Net increase (decrease) in cash and cash equivalents	27,408,000	(101,870,000)
Cash and cash equivalents at beginning of year	141,273,000	193,738,000
Cash and cash equivalents at end of period	$ 168,681,000	$ 91,868,000