Quarterly report pursuant to Section 13 or 15(d)

Other Assets (Schedule Of Other Assets) (Details)

v2.4.1.9
Other Assets (Schedule Of Other Assets) (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Schedule of Prepaid Expenses [Line Items]    
Plugging and abandonment escrow account on the WCBB properties (Note 8) $ 3,089,000gpor_PluggingAndAbandonmentEscrowAccount $ 3,097,000gpor_PluggingAndAbandonmentEscrowAccount
Certificates of Deposit securing letter of credit 275,000gpor_CertificatesOfDepositSecuringLetterOfCredit 275,000gpor_CertificatesOfDepositSecuringLetterOfCredit
Prepaid drilling costs 269,000gpor_PrepaidDrillingCosts 483,000gpor_PrepaidDrillingCosts
Loan commitment fees 14,771,000us-gaap_UnamortizedLoanCommitmentAndOriginationFeesAndUnamortizedDiscountsOrPremiums 15,390,000us-gaap_UnamortizedLoanCommitmentAndOriginationFeesAndUnamortizedDiscountsOrPremiums
Deposits 34,000us-gaap_DepositAssets 34,000us-gaap_DepositAssets
Other 128,000gpor_OtherAssetsOther 117,000gpor_OtherAssetsOther
Other assets 18,566,000us-gaap_OtherAssetsNoncurrent 19,396,000us-gaap_OtherAssetsNoncurrent
Prepaid Expenses and Other Current Assets [Member]    
Schedule of Prepaid Expenses [Line Items]    
Prepaid taxes 12,100,000us-gaap_PrepaidTaxes
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember 		 
Prepaid insurance 2,300,000us-gaap_PrepaidInsurance
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember 		 
Prepaid other expenses $ 1,400,000us-gaap_OtherPrepaidExpenseCurrent
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember