Consolidated Statements of Cash Flows - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net income (loss)		$ 165,891	$ (132,988)
Loss from discontinued operations, net of tax	[1]	(3,702)	(299,538)
Income from continuing operations		169,593	166,550
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization		155,138	163,226
Deferred income taxes		(16,777)	(1,346)
Changes in current assets and liabilities, net of acquisitions:
Receivables		(121,128)	(75,308)
Inventories		2,047	(4,153)
Other current assets		(40,655)	(18,824)
Accounts payable		30,097	15,514
Other current liabilities		66,647	48,973
Other noncurrent changes		(15,081)	(25,284)
Net cash provided by continuing operations		229,881	269,348
Net cash provided by discontinued operations		42,020	7,127
Net cash provided by operating activities		271,901	276,475
Investing activities:
Capital expenditures		(222,084)	(303,873)
Net proceeds from sale or disposition of property and other		121,162	17,583
Investments		(260)	56
Net cash used in continuing operations		(101,182)	(286,234)
Net cash provided by discontinued operations		2,234	31,918
Net cash used in investing activities		(98,948)	(254,316)
Financing activities:
Issuance of long-term debt		133,437	341,777
Repayment of long-term debt		(183,968)	(236,433)
Dividends paid		(113,131)	(110,366)
Redemption of preferred stock		(15,600)	0
Repurchase of common stock		(1,684)	0
Tax withholding on stock-based compensation		(757)	(323)
Net cash used in continuing operations		(181,703)	(5,345)
Net cash used in discontinued operations		0	(40,852)
Net cash used in financing activities		(181,703)	(46,197)
Effect of exchange rate changes on cash and cash equivalents		(1)	3
Decrease in cash and cash equivalents		(8,751)	(24,035)
Cash and cash equivalents -- beginning of year		46,107	83,903
Cash and cash equivalents -- end of period		$ 37,356	$ 59,868

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