Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net income	$ 193,490	$ 165,891
Income (loss) from discontinued operations, net of tax	85	(3,702)
Income from continuing operations	193,405	169,593
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	161,298	155,138
Deferred income taxes	42,428	(16,777)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(55,749)	(121,128)
Inventories	(38,785)	2,047
Other current assets	(3,452)	(40,655)
Accounts payable	16,155	30,097
Other current liabilities	31,971	66,647
Other noncurrent changes	(27,170)	(15,081)
Net cash provided by continuing operations	320,101	229,881
Net cash provided by (used in) discontinued operations	(2,720)	42,020
Net cash provided by operating activities	317,381	271,901
Investing activities:
Capital expenditures	(345,599)	(222,084)
Acquisitions, net of cash acquired	(27,858)	0
Net proceeds from sale or disposition of property and other	12,451	121,162
Investments	(1,560)	(260)
Net cash used in continuing operations	(362,566)	(101,182)
Net cash provided by discontinued operations	1,236	2,234
Net cash used in investing activities	(361,330)	(98,948)
Financing activities:
Issuance of long-term debt	356,952	133,437
Repayment of long-term debt	(157,315)	(183,968)
Dividends paid	(115,859)	(113,131)
Redemption of preferred stock	0	(15,600)
Repurchase of common stock	(5,020)	(1,684)
Tax withholding on stock-based compensation	(2,330)	(757)
Net cash provided by (used in) continuing operations	76,428	(181,703)
Net cash provided by discontinued operations	0	0
Net cash provided by (used in) financing activities	76,428	(181,703)
Effect of exchange rate changes on cash and cash equivalents	(1)	(1)
Increase (decrease) in cash and cash equivalents	32,478	(8,751)
Cash and cash equivalents -- beginning of year	34,599	46,107
Cash and cash equivalents -- end of period	$ 67,077	$ 37,356