Consolidated Statements of Cash Flows - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Operating activities:
Net income (loss)		$ 78,539	$ (215,974)
Loss from discontinued operations, net of tax	[1]	(1,504)	(294,138)
Income from continuing operations		80,043	78,164
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization		102,983	109,132
Deferred income taxes		(5,293)	3,608
Changes in current assets and liabilities, net of acquisitions:
Receivables		(43,478)	(44,909)
Inventories		(13,573)	(23,189)
Other current assets		(15,799)	(20,555)
Accounts payable		11,611	7,339
Other current liabilities		(6,387)	33,214
Other noncurrent changes		(4,460)	(14,626)
Net cash provided by continuing operations		105,647	128,178
Net cash provided by (used in) discontinued operations		33,846	(25,529)
Net cash provided by operating activities		139,493	102,649
Investing activities:
Capital expenditures		(143,764)	(220,098)
Net proceeds from sale or disposition of property and other		119,361	14,778
Investments		(358)	(262)
Net cash used in continuing operations		(24,761)	(205,582)
Net cash provided by discontinued operations		2,234	28,040
Net cash used in investing activities		(22,527)	(177,542)
Financing activities:
Issuance of long-term debt		63,827	387,625
Repayment of long-term debt		(93,275)	(196,771)
Dividends paid		(75,535)	(73,575)
Redemption of preferred stock		(15,600)	0
Repurchase of common stock		(1,684)	0
Tax withholding on stock-based compensation		(757)	(323)
Net cash provided by (used in) continuing operations		(123,024)	116,956
Net cash used in discontinued operations		0	(40,852)
Net cash provided by (used in) financing activities		(123,024)	76,104
Effect of exchange rate changes on cash and cash equivalents		(1)	3
Increase (decrease) in cash and cash equivalents		(6,059)	1,214
Cash and cash equivalents -- beginning of year		46,107	83,903
Cash and cash equivalents -- end of period		$ 40,048	$ 85,117

[1] Includes eliminations for the presentation of income tax adjustments between continuing and discontinued operations.