CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating activities:
Net income (loss)	$ 13,002	$ 58,026	$ (239,256)
Adjustments to reconcile net income (loss) to net cash provided from operating activities:
(Gain) loss from discontinued operations		(15,320)	327,954
Loss (gain) from equity method investments, net of distributions	5,670	16,871	(7,366)
Deferred income tax expense	13,832	34,920	51,746
Depletion, depreciation and amortization and proved property impairment	480,782	379,902	281,743
Exploration dry hole costs	841	3,888	3,700
Mark-to-market on natural gas and oil derivatives not designated as hedges (gain) loss	(5,958)	(15,762)	2,086
Abandonment and impairment of unproved properties	125,278	79,703	49,738
Unrealized derivative loss (gain)	3,221	(2,183)	(2,387)
Allowance for bad debts	750	946	3,608
Amortization of deferred financing costs, loss on extinguishment of debt and other	23,165	25,458	10,072
Deferred and stock-based compensation	60,136	86,979	34,964
Gain on the sale of assets	(49,132)	(2,259)	(76,642)
Changes in working capital:
Accounts receivable	(48,986)	(52,112)	(6,512)
Inventory and other	(7,376)	865	(333)
Accounts payable	13,654	738	2,867
Accrued liabilities and other	18,220	9,540	(2,096)
Net cash provided from continuing operations	647,099	610,200	433,886
Net cash provided from discontinued operations		21,437	79,436
Net cash provided from operating activities	647,099	631,637	513,322
Investing activities:
Additions to natural gas and oil properties	(1,498,628)	(1,199,545)	(732,860)
Additions to field service assets	(4,762)	(11,607)	(14,944)
Acreage and proved property purchases	(191,065)	(226,500)	(296,503)
Investment in equity method investments and other assets			(45)
Proceeds from disposal of assets	168,219	53,926	327,765
Purchase of marketable securities held by the deferred compensation plan	(60,406)	(25,388)	(17,670)
Proceeds from the sales of marketable securities held by the deferred compensation plan	58,084	20,410	19,572
Net cash used in investing activities from continuing operations	(1,528,558)	(1,388,704)	(714,685)
Net cash provided from (used in) investing activities from discontinued operations		840,723	(84,173)
Net cash used in investing activities	(1,528,558)	(547,981)	(798,858)
Financing activities:
Borrowing on credit facilities	1,773,000	887,826	1,055,000
Repayment on credit facilities	(1,221,000)	(974,826)	(1,105,000)
Issuance of subordinated notes	600,000	500,000	500,000
Repayment of subordinated notes	(259,375)	(413,697)	(202,458)
Dividends paid	(25,981)	(25,756)	(25,574)
Debt issuance costs	(12,605)	(22,003)	(9,600)
Issuance of common stock	2,073	619	5,903
Change in cash overdrafts	(1,126)	(51,474)	64,100
Proceeds from the sales of common stock held by the deferred compensation plan	26,633	12,899	5,246
Net cash provided from (used in) financing activities	881,619	(86,412)	287,617
Increase (decrease) in cash and cash equivalents	160	(2,756)	2,081
Cash and cash equivalents at beginning of year	92	2,848	767
Cash and cash equivalents at end of year	$ 252	$ 92	$ 2,848