Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Operating activities:
Net income (loss)	$ 294,338		$ 278,570		$ (754)
Income (loss) from discontinued operations, net of tax	3,177	[1]	(312)	[1]	13,567	[1]
Income (loss) from continuing operations	291,161		278,882		(14,321)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	401,368		386,856		359,205
Earnings (loss), net of distributions, from equity method investments	550		2,281		(618)
Deferred income taxes	87,015		86,778		(7,503)
Unrealized (gain) loss on commodity derivatives	(23,400)		6,267		624
Write-downs of oil and natural gas properties (Note 1)	0		0		391,800
Excess tax benefit on stock-based compensation	(4,729)		0		(26)
Changes in current assets and liabilities, net of acquisitions:
Receivables	6,166		(40,669)		(13,416)
Inventories	(18,738)		30,452		(42,334)
Other current assets	(25,997)		(9,474)		297
Accounts payable	(45,065)		15,084		6,352
Other current liabilities	(23,515)		29,392		(59,001)
Other noncurrent changes	(29,193)		(43,937)		(33,639)
Net cash provided by continuing operations	615,623		741,912		587,420
Net cash provided by (used in) discontinued operations	159		281		(2,680)
Net cash provided by operating activities	615,782		742,193		584,740
Investing activities:
Capital expenditures	(972,102)		(909,400)		(872,920)
Acquisitions, net of cash acquired	(209,213)		0		(67,261)
Net proceeds from sale or disposition of property and other	276,415		124,541		40,110
Investments	709		302		9,725
Proceeds from sale of equity method investments	0		1,896		2,394
Net cash used in continuing operations	(904,191)		(782,661)		(887,952)
Net cash provided by discontinued operations	0		0		0
Net cash used in investing activities	(904,191)		(782,661)		(887,952)
Financing activities:
Issuance of short-term borrowings	0		9,500		20,100
Repayment of short-term borrowings	(11,500)		0		0
Issuance of long-term debt	606,084		507,924		467,957
Repayment of long-term debt	(368,803)		(423,707)		(138,775)
Proceeds from issuance of common stock	150,060		14,554		88
Dividends paid	(136,712)		(98,405)		(159,768)
Excess tax benefit on stock-based compensation	4,729		0		26
Tax withholding on stock-based compensation	(5,564)		0		0
Contribution from noncontrolling interest	86,900		27,000		0
Net cash provided by continuing operations	325,194		36,866		189,628
Net cash provided by discontinued operations	0		0		0
Net cash provided by financing activities	325,194		36,866		189,628
Effect of exchange rate changes on cash and cash equivalents	(155)		(215)		(146)
Increase (decrease) in cash and cash equivalents	36,630		(3,817)		(113,730)
Cash and cash equivalents - beginning of year	45,225		49,042		162,772
Cash and cash equivalents - end of year	$ 81,855		$ 45,225		$ 49,042

[1] Reflected in the Other category.