Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Operating activities:
Net income	$ 109,466	$ 102,848
Income (loss) from discontinued operations, net of tax	502	(136)
Income from continuing operations	108,964	102,984
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	202,683	188,850
Loss, net of distributions, from equity method investments	245	1,491
Deferred income taxes	60,141	19,790
Unrealized (gain) loss on commodity derivatives	11,908	(7,215)
Excess tax benefit on stock-based compensation	(4,729)	0
Changes in current assets and liabilities, net of acquisitions:
Receivables	(8,501)	(65,637)
Inventories	(48,857)	(29,923)
Other current assets	(37,460)	(18,044)
Accounts payable	(23,277)	18,940
Other current liabilities	(36,447)	23,071
Other noncurrent changes	(13,638)	(741)
Net cash provided by continuing operations	211,032	233,566
Net cash provided by (used in) discontinued operations	(491)	360
Net cash provided by operating activities	210,541	233,926
Investing activities:
Capital expenditures	(390,126)	(431,439)
Acquisitions, net of cash acquired	(206,304)	0
Net proceeds from sale or disposition of property and other	11,917	20,884
Investments	(1,208)	16
Net cash used in continuing operations	(585,721)	(410,539)
Net cash provided by discontinued operations	0	0
Net cash used in investing activities	(585,721)	(410,539)
Financing activities:
Issuance of short-term borrowings	0	29,600
Repayment of short-term borrowings	(11,500)	0
Issuance of long-term debt	441,447	450,461
Repayment of long-term debt	(111,539)	(214,473)
Proceeds from issuance of common stock	132,268	0
Dividends paid	(67,717)	(32,915)
Excess tax benefit on stock-based compensation	4,729	0
Contribution from noncontrolling interest	32,500	10,000
Net cash provided by continuing operations	420,188	242,673
Net cash provided by discontinued operations	0	0
Net cash provided by financing activities	420,188	242,673
Effect of exchange rate changes on cash and cash equivalents	85	(131)
Increase in cash and cash equivalents	45,093	65,929
Cash and cash equivalents - beginning of year	45,225	49,042
Cash and cash equivalents - end of period	$ 90,318	$ 114,971