CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net earnings	$ 419,491	$ 221,177	$ 204,923
Adjustments to reconcile net earnings to net cash provided by operating activities
Depreciation, depletion, accretion and amortization	284,940	274,823	279,497
Net gain on sale of property, plant & equipment and businesses	(15,431)	(9,927)	(244,222)
Contributions to pension plans	(9,576)	(14,047)	(5,488)
Share-based compensation expense	20,670	18,248	23,884
Excess tax benefits from share-based compensation	0	(18,376)	(3,464)
Deferred tax expense (benefit)	33,591	3,069	18,378
Cost of debt purchase	0	67,075	72,949
(Increase) decrease in assets excluding the initial effects of business acquisitions and dispositions
Accounts and notes receivable	(72,763)	(42,164)	(25,118)
Inventories	1,625	(20,925)	(5,595)
Prepaid expenses	2,558	(5,288)	(6,256)
Other assets	(18,236)	34,863	(13,930)
Increase (decrease) in liabilities excluding the initial effects of business acquisitions and dispositions
Accrued interest and income taxes	(7,187)	26,605	(3,840)
Trade payables and other accruals	30,353	26,491	4,229
Other noncurrent liabilities	(29,138)	(42,702)	(42,810)
Other, net	3,691	616	7,870
Net cash provided by operating activities	644,588	519,538	261,007
Investing Activities
Purchases of property, plant & equipment	(350,148)	(289,262)	(224,852)
Proceeds from sale of property, plant & equipment	23,318	8,218	26,028
Proceeds from sale of businesses, net of transaction costs	0	0	721,359
Payment for businesses acquired, net of acquired cash	(32,537)	(27,198)	(284,237)
Increase in restricted cash	(7,883)	(1,150)	0
Other, net	2,173	(350)	33
Net cash provided by (used for) investing activities	(365,077)	(309,742)	238,331
Financing Activities
Proceeds from line of credit	3,000	441,000	93,000
Payment of line of credit	(3,000)	(206,000)	(93,000)
Payment of current maturities and long-term debt	(130)	(695,060)	(579,829)
Proceeds from issuance of long-term debt	0	400,000	0
Debt and line of credit issuance costs	(1,860)	(7,382)	0
Purchases of common stock	(161,463)	(21,475)	0
Proceeds from issuance of common stock	0	0	30,620
Dividends paid	(106,333)	(53,214)	(28,884)
Proceeds from exercise of stock options	0	72,971	23,502
Share-based compensation, shares withheld for taxes	(34,797)	(16,160)	(671)
Excess tax benefits from share-based compensation	0	18,376	3,464
Other, net	(2)	(65)	(5)
Net cash used for financing activities	(304,585)	(67,009)	(551,803)
Net increase (decrease) in cash and cash equivalents	(25,074)	142,787	(52,465)
Cash and cash equivalents at beginning of year	284,060	141,273	193,738
Cash and cash equivalents at end of year	$ 258,986	$ 284,060	$ 141,273