Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows from Operating Activities:
Consolidated net earnings	$ 42,826	$ 10,040
Adjustments to reconcile consolidated net earnings to net cash provided by operating activities:
Depreciation, depletion and amortization	89,211	76,821
Stock-based compensation expense	13,552	9,760
Gain on divestitures and sales of assets	(2,413)	(951)
Deferred income taxes	4,781	2,029
Other items, net	495	(2,269)
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable, net	(26,059)	20,951
Inventories, net	16,416	(8,873)
Accounts payable	20,393	7,925
Other assets and liabilities, net	(41,338)	(10,421)
Net Cash Provided by Operating Activities	117,864	105,012
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(130,056)	(96,259)
Proceeds from divestitures and sales of assets	2,927	2,528
Payment of railcar construction advances		(8,430)
Reimbursement of railcar construction advances		8,430
Investments in life insurance contracts, net	193	99
Other investing activities, net	(600)
Net Cash Used for Investing Activities	(127,536)	(93,632)
Cash Flows from Financing Activities:
Borrowings of debt	125,000
Repayments of debt	(85,000)	(13)
Payments on finance leases	(951)
Payments on capital lease		(829)
Debt issuance costs		(3,194)
Contributions by owners of noncontrolling interest		129
Dividends paid	(30,395)	(27,885)
Proceeds from exercise of stock options	611	2,801
Shares withheld for employees' income tax obligations	(7,128)	(6,380)
Net Cash Provided by (Used for) Financing Activities	2,137	(35,371)
Net Decrease in Cash and Cash Equivalents	(7,535)	(23,991)
Cash and Cash Equivalents, beginning of period	44,892	1,446,364
Cash and Cash Equivalents, end of period	$ 37,357	$ 1,422,373