Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash Flows from Operating Activities:
Consolidated net earnings	$ 167,169	$ 88,138
Adjustments to reconcile consolidated net earnings to net cash provided by operating activities:
Depreciation, depletion and amortization	139,617	134,958
Stock-based compensation expense	12,801	7,524
Gain on divestitures and sales of assets	(261)	(853)
Deferred income taxes	34,389	33,906
Excess tax benefits from stock-based compensation transactions	(3,948)	(55)
Other items, net	(5,767)	(341)
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable, net	(117,524)	(76,061)
Inventories, net	(33,131)	(27,661)
Accounts payable	32,521	(3,416)
Other assets and liabilities, net	(22,495)	(29,070)
Net Cash Provided by Operating Activities	203,371	127,069
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(210,559)	(127,990)
Acquisitions, net	(123,000)	(10,713)
Cash received in acquisition	3,446
Proceeds from divestitures and sales of assets	4,474	1,972
Repayments from affiliate		1,808
Payment of railcar construction advances		(25,234)
Reimbursement of railcar construction advances		25,234
Net Cash Used for Investing Activities	(325,639)	(134,923)
Cash Flows from Financing Activities:
Borrowings of debt	280,000	80,000
Repayments of debt	(70,420)	(8,144)
Payments on capital lease obligations	(1,563)	(1,831)
Change in bank overdraft	(3,092)	(183)
Dividends paid	(51,467)	(54,285)
Issuances of common stock	15,049	27,760
Repurchases of common stock	(190,000)	(100,000)
Excess tax benefits from stock-based compensation transactions	3,948	55
Net Cash Used for Financing Activities	(17,545)	(56,628)
Net Decrease in Cash and Cash Equivalents	(139,813)	(64,482)
Cash and Cash Equivalents, beginning of period	168,409	108,651
Cash and Cash Equivalents, end of period	28,596	44,169
Supplemental Disclosures of Cash Flow Information:
Cash paid for interest	36,630	35,447
Cash paid for income taxes	$ 47,159	$ 24,334