Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Break-Down Of Long-Term Debt) (Details)

v2.4.1.9
Long-Term Debt (Break-Down Of Long-Term Debt) (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2011
Aug. 18, 2014
Dec. 21, 2012
Oct. 17, 2012
Debt Instrument [Line Items]            
Unamortized original issue (discount) premium, net (4) $ 14,130,000us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet [1] $ 14,658,000us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet [1]        
Less: current maturities of long term debt (1,781,000)us-gaap_LongTermDebtCurrent (168,000)us-gaap_LongTermDebtCurrent        
Long-term debt, net of current maturities 779,130,000us-gaap_LongTermDebtNoncurrent 716,316,000us-gaap_LongTermDebtNoncurrent        
Line of Credit [Member]            
Debt Instrument [Line Items]            
Long-term debt 165,000,000us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember
[2] 100,000,000us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember
[2]        
Building loans [Member]            
Debt Instrument [Line Items]            
Long-term debt 1,781,000us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= gpor_BuildingLoansMember
[3] 1,826,000us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= gpor_BuildingLoansMember
[3] 2,400,000us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= gpor_BuildingLoansMember
     
7.75% senior unsecured notes due 2020 [Member]            
Debt Instrument [Line Items]            
Long-term debt $ 600,000,000us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
[4] $ 600,000,000us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
[4]   $ 600,000,000.0us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
$ 600,000,000.0us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
$ 600,000,000.0us-gaap_LongTermDebt
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SeniorNotesMember
[1] The October Notes were issued at a price of 98.534% resulting in a gross discount of $3.7 million and an effective rate of 8.000%. The December Notes were issued at a price of 101.000% resulting in a gross premium of $0.5 million and an effective rate of 7.531%. The August Notes were issued at a price of 106.000% resulting in a gross premium of $18.0 million and an effective rate of 6.561%. The premium and discount are being amortized using the effective interest method.
[2] On December 27, 2013, the Company entered into an Amended and Restated Credit Agreement with The Bank of Nova Scotia, as administrative agent, sole lead arranger and sole bookrunner, Amegy Bank National Association, as syndication agent, KeyBank National Association, as documentation agent, and other lenders (The "Amended and Restated Credit Agreement") that provides for a maximum facility amount of $1.5 billion. The Amended and Restated Credit Agreement matures on June 6, 2018. The Company’s wholly-owned subsidiaries have guaranteed the obligations of the Company under the Amended and Restated Credit Agreement. On April 23, 2014, the Company entered into a first amendment to the Amended and Restated Credit Agreement. The first amendment increased the letter of credit sublimit from $20.0 million to $70.0 million and provided for an increase in the borrowing base availability from $150.0 million to $275.0 million. The first amendment also made certain changes to the lenders and their respective lending commitments thereunder. On November 26, 2014, the Company entered into a second amendment to the Amended and Restated Credit Agreement. The second amendment changed the definition of EBITDAX to exclude proceeds from the disposition of equity method investments and changed the ratio of funded debt to EBITDAX to be the ratio of net funded debt to EBITDAX. Net funded debt is funded debt less the amount of cash and short-term investments the Company has at the end of the relevant fiscal quarter. The second amendment increases the ratio from 2.00 to 1.00 to 3.50 to 1.00 for the period December 31, 2014 through June 30, 2015 and then decreases the ratio to 3.25 to 1.00 for the periods thereafter. Further, the second amendment increased the letter of credit sublimit from $70.0 million to $125.0 million and provided for an increase in the borrowing base availability from $275.0 million to $450.0 million. As of March 31, 2015, $165.0 million was outstanding under the Amended and Restated Credit Agreement. At March 31, 2015, the total availability for future borrowings under the Amended and Restated Credit Agreement, after giving effect to an aggregate of $68.2 million of letters of credit, was $216.8 million.On April 10, 2015, the Company entered into a third amendment to the Amended and Restated Credit Agreement. The third amendment increased the borrowing base from $450.0 million to $575.0 million and increased the Company's basket for unsecured debt issuances to $1.2 billion. The third amendment also made certain changes to the lenders and their respective lending commitments thereunder.Advances under the Amended and Restated Credit Agreement may be in the form of either base rate loans or eurodollar loans. The interest rate for base rate loans is equal to (1) the applicable rate, which ranges from 0.50% to 1.50%, plus (2) the highest of: (a) the federal funds rate plus 0.50%, (b) the rate of interest in effect for such day as publicly announced from time to time by agent as its “prime rate,” and (c) the eurodollar rate for an interest period of one month plus 1.00%. The interest rate for eurodollar loans is equal to (1) the applicable rate, which ranges from 1.50% to 2.50%, plus (2) the London interbank offered rate that appears on pages LIBOR01 or LIBOR02 of the Reuters screen that displays such rate for deposits in U.S. dollars, or, if such rate is not available, the rate as administered by ICE Benchmark Administration (or any other person that takes over administration of such rate) per annum equal to the offered rate on such other page or service that displays on average London interbank offered rate as determined by ICE Benchmark Administration (or any other person that takes over administration of such rate) for deposits in U.S. dollars, or, if such rate is not available, the average quotations for three major New York money center banks of whom the agent shall inquire as the “London Interbank Offered Rate” for deposits in U.S. dollars. At March 31, 2015, amounts borrowed under the Amended and Restated Credit Agreement bore interest at the Eurodollar rate (2.18%).The Amended and Restated Credit Agreement contains customary negative covenants including, but not limited to, restrictions on the Company’s and its subsidiaries’ ability to: •incur indebtedness; •grant liens; •pay dividends and make other restricted payments; •make investments; •make fundamental changes; •enter into swap contracts and forward sales contracts; •dispose of assets; •change the nature of their business; and •enter into transactions with affiliates. The negative covenants are subject to certain exceptions as specified in the Amended and Restated Credit Agreement. The Amended and Restated Credit Agreement also contains certain affirmative covenants, including, but not limited to the following financial covenants: (i) the ratio of net funded debt to EBITDAX (net income, excluding (i) any non-cash revenue or expense associated with swap contracts resulting from ASC 815 and (ii) any cash or noncash revenue or expense attributable to minority investments plus without duplication and, in the case of expenses, to the extent deducted from revenues in determining net income, the sum of (a) the aggregate amount of consolidated interest expense for such period, (b) the aggregate amount of income, franchise, capital or similar tax expense (other than ad valorem taxes) for such period, (c) all amounts attributable to depletion, depreciation, amortization and asset or goodwill impairment or writedown for such period, (d) all other non-cash charges, (e) exploration costs deducted in determining net income under successful efforts accounting, (f) actual cash distributions received from minority investments, (g) to the extent actually reimbursed by insurance, expenses with respect to liability on casualty events or business interruption, and (h) all reasonable transaction expenses related to dispositions and acquisitions of assets, investments and debt and equity offerings (provided that expenses related to any unsuccessful disposition will be limited to $3.0 million in the aggregate) for a twelve-month period may not be greater than 3.50 to 1.00; for the period December 31, 2014 through June 30, 2015 and 3.25 to 1.00 for the twelve-month period ending September 30, 2015 and periods thereafter; and (ii) the ratio of EBITDAX to interest expense for a twelve-month period may not be less than 3.00 to 1.00. The Company was in compliance with all covenants at March 31, 2015.
[3] In March 2011, the Company entered into a new building loan agreement for the office building it occupies in Oklahoma City, Oklahoma. The new loan agreement refinanced the $2.4 million outstanding under the previous building loan agreement. The new agreement matures in February 2016 and bears interest at the rate of 5.82% per annum. The new building loan requires monthly interest and principal payments of approximately $22,000 and is collateralized by the Oklahoma City office building and associated land.
[4] On October 17, 2012, the Company issued $250.0 million in aggregate principal amount of senior unsecured notes due 2020 (the "October Notes") to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the "October Notes Offering") under an indenture among the Company, its subsidiary guarantors and Wells Fargo Bank, National Association, as the trustee (the "senior note indenture"). On December 21, 2012, the Company issued an additional $50.0 million in aggregate principal amount of senior unsecured notes due 2020 (the "December Notes") to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act ("the December Notes Offering"). The December Notes were issued as additional securities under the senior note indenture. The Company used a portion of the net proceeds from the October Notes Offering to repay all amounts outstanding at such time under its revolving credit facility. The Company used the remaining net proceeds of the October Notes Offering and the net proceeds of the December Notes Offering for general corporate purposes, which included funding a portion of its 2013 capital development plan. The October Notes and the December Notes were exchanged for substantially identical notes in the same aggregate principal amount that were registered under the Securities Act in October 2013 (the "Exchange Notes").On August 18, 2014, the Company issued an additional $300.0 million in aggregate principal amount of senior unsecured notes due 2020 (the "August Notes") to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act ("the August Notes Offering"). The August Notes were issued as additional securities under the senior note indenture. The Company used a portion of the net proceeds from the August Notes Offering to repay all amounts outstanding at such time under its revolving credit facility. The Company intends to use the remaining net proceeds of the August Notes Offering for general corporate purposes, including funding a portion of its 2014 and 2015 capital development plans. The October Notes Offering, December Notes Offering and the August Notes Offering are collectively referred to as the "Notes Offerings" and the Exchange Notes, and the August Notes are collectively referred to as the "Old Notes".In connection with the issuance of the August Notes, the Company and the subsidiary guarantors entered into a registration rights agreement with the initial purchasers on August 18, 2014, pursuant to which the Company and the subsidiary guarantors have agreed to file a registration statement with respect to an offer to exchange the August Notes for a new issue of substantially identical debt securities registered under the Securities Act. The registration statement relating to the exchange offer for the August Notes was filed on November 6, 2014, as amended on February 3, 2015, and declared effective by the SEC on February 4, 2015. The exchange offer for the August Notes was completed in March 2015.Under the senior note indenture relating to the Old Notes, interest on the Old Notes accrues at a rate of 7.75% per annum on the outstanding principal amount from October 17, 2012, payable semi-annually on May 1 and November 1 of each year, commencing on May 1, 2013. The Old Notes are the Company's senior unsecured obligations and rank equally in the right of payment with all of the Company's other senior indebtedness and senior in right of payment to any future subordinated indebtedness. All of the Company's existing and future restricted subsidiaries that guarantee the Company's secured revolving credit facility or certain other debt guarantee the Old Notes; provided, however, that the Old Notes are not guaranteed by Grizzly Holdings, Inc. and will not be guaranteed by any of the Company's future unrestricted subsidiaries. The Company may redeem some or all of the Old Notes at any time on or after November 1, 2016, at the redemption prices listed in the senior note indenture. Prior to November 1, 2016, the Company may redeem the Old Notes at a price equal to 100% of the principal amount plus a “make-whole” premium. In addition, prior to November 1, 2015, the Company may redeem up to 35% of the aggregate principal amount of the Old Notes with the net proceeds of certain equity offerings, provided that at least 65% of the aggregate principal amount of the Old Notes initially issued remains outstanding immediately after such redemption.