CONDENSED CONSOLIDATED BALANCE SHEET (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 13,948	$ 20,954
Accounts receivable, net	185,281us-gaap_ReceivablesNetCurrent	239,009us-gaap_ReceivablesNetCurrent
Inventories	14,087us-gaap_InventoryNet	14,026us-gaap_InventoryNet
Derivative instruments	134,041us-gaap_DerivativeInstrumentsAndHedges	137,603us-gaap_DerivativeInstrumentsAndHedges
Other current assets	2,046us-gaap_OtherAssetsCurrent	1,855us-gaap_OtherAssetsCurrent
Total current assets	349,403us-gaap_AssetsCurrent	413,447us-gaap_AssetsCurrent
Properties and equipment, net (Successful efforts method)	5,058,804us-gaap_PropertyPlantAndEquipmentNet	4,925,711us-gaap_PropertyPlantAndEquipmentNet
Equity method investments	74,528us-gaap_EquityMethodInvestments	68,029us-gaap_EquityMethodInvestments
Other assets	29,588us-gaap_OtherAssetsNoncurrent	30,529us-gaap_OtherAssetsNoncurrent
TOTAL ASSETS	5,512,323us-gaap_Assets	5,437,716us-gaap_Assets
Current liabilities
Accounts payable	321,215us-gaap_AccountsPayableCurrent	400,076us-gaap_AccountsPayableCurrent
Accrued liabilities	34,579us-gaap_AccruedLiabilitiesCurrent	63,669us-gaap_AccruedLiabilitiesCurrent
Income taxes payable	7,808us-gaap_AccruedIncomeTaxesCurrent	0us-gaap_AccruedIncomeTaxesCurrent
Deferred income taxes	39,144us-gaap_DeferredTaxLiabilitiesCurrent	35,273us-gaap_DeferredTaxLiabilitiesCurrent
Total current liabilities	402,746us-gaap_LiabilitiesCurrent	499,018us-gaap_LiabilitiesCurrent
Postretirement benefits	36,448	35,827
Long-term debt	1,877,000us-gaap_LongTermDebtNoncurrent	1,752,000us-gaap_LongTermDebtNoncurrent
Deferred income taxes	851,649	843,876
Asset retirement obligations	130,541	124,655
Other liabilities	38,408us-gaap_OtherLiabilitiesNoncurrent	39,607us-gaap_OtherLiabilitiesNoncurrent
Total liabilities	3,336,792us-gaap_Liabilities	3,294,983us-gaap_Liabilities
Commitments and contingencies
Stockholders' equity
Common stock: Authorized -- 960,000,000 shares of $0.10 par value in 2015 and 2014, respectively Issued-- 423,496,205 shares and 422,915,258 shares in 2015 and 2014, respectively	42,350us-gaap_CommonStockValue	42,292us-gaap_CommonStockValue
Additional paid-in capital	711,180	710,432
Retained earnings	1,730,987	1,698,995
Accumulated other comprehensive income (loss)	(2,151)	(2,151)
Less treasury stock, at cost: 9,892,680 shares in 2015 and 2014, respectively	(306,835)us-gaap_TreasuryStockValue	(306,835)us-gaap_TreasuryStockValue
Total stockholders' equity	2,175,531us-gaap_StockholdersEquity	2,142,733us-gaap_StockholdersEquity
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 5,512,323	$ 5,437,716

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Subparagraph a

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682