Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Details)

v2.4.1.9
Stock-Based Compensation (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
0 Months Ended 9 Months Ended 1 Months Ended 0 Months Ended
Aug. 15, 2014
Mar. 31, 2015
Mar. 31, 2014
Oct. 31, 2014
Oct. 31, 2013
Oct. 17, 2014
Oct. 10, 2014
Jul. 01, 2014
Jan. 16, 2013
Jan. 15, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Number of stock options exercised   494,791us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised 0us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised              
Issuance of common stock (in shares)   272,898us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod                
Number of stock options forfeited/canceled   2,882,085us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod 41,666us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod              
Value of stock repurchased   $ 1,445us-gaap_StockRepurchasedDuringPeriodValue                
Repurchase of common stock   566us-gaap_PaymentsForRepurchaseOfCommonStock 11us-gaap_PaymentsForRepurchaseOfCommonStock              
Stock issued, in shares   1,785,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross                
Expired (in shares)   25,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod              
Unvested options forfeited 1,369,585us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares                  
Exercise price of options (in dollars per share)   $ 1.73us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice                
TBOs                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Stock issued, in shares   135,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_TimedBasedOptionsMember
               
Restricted Stock                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Share-based compensation expense (reversal of expense)   (44)us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
               
PBOs                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Stock issued, in shares   1,250,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
1,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
             
PBOs | CO2-EOR Development Project at Poplar                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Performance metrics weighted average       20.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_CO2EORDevelopmentProjectatPoplarMember
40.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_CO2EORDevelopmentProjectatPoplarMember
         
PBOs | Preparing Poplar of commercially viable CO2-EOR Development                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Performance metrics weighted average       40.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_PreparingPoplarofCommerciallyViableCO2EORDevelopmentMember
           
PBOs | Progressing UK operations in the Weald Basin                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Performance metrics weighted average       20.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_ProgressingUKOperationsintheWealdBasinMember
           
PBOs | Moving forward with Farnham Dome Project                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Performance metrics weighted average       20.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_MovingForwardwithFarnhamDomeProjectMember
           
PBOs | CO2-EOR Pilot Program at Poplar                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Performance metrics weighted average         10.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_CO2EORPilotProgramatPoplarMember
         
PBOs | Sale of Substantially All of the Amadeus Basin Assets                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Performance metrics weighted average         20.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_SaleofSubstantiallyAlloftheAmadeusBasinAssetsMember
         
PBOs | Approval of a Farmout Agreement or Participation in Drilling a Well in the Weald Basin                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Performance metrics weighted average         20.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_ApprovalofaFarmoutAgreementorParticipationinDrillingaWellintheWealdBasinMember
         
PBOs | Approval of a Farmout Agreement in the Bonaparte Basin                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Performance metrics weighted average         10.00%mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformanceMetricsWeightedAveragePercentage
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ mpet_PerformanceMetricsWeightedAverageAxis
= mpet_ApprovalofaFarmoutAgreementintheBonaparteBasinMember
         
Employee Stock Option                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Share-based compensation expense (reversal of expense)   (430)us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
               
Unrecorded expected future compensation expense related to stock option awards   1,424us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1,500us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
             
RSUs                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Unvested RSUs forfeited 100,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
                 
Market Based Options                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Per share closing price (in dollars per share)   $ 2.35mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardsMinimumPerShareClosingPriceforVesting
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
               
Number of consecutive trading days       10mpet_MarketBasedStockOptionsNumberofConsecutiveTradingDays
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
           
Stock issued, in shares   400,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
1,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
             
Employee Stock Option                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Maximum number of shares allowed to be issued each year                 1,000,000mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityOtherthanOptionsMaximumNumberofSharesAllowedtobeIssuedPerPersonPerYear
/ us-gaap_StatementClassOfStockAxis
= us-gaap_EmployeeStockOptionMember
 
RSUs                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Maximum number of shares allowed to be issued each year                 500,000mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityOtherthanOptionsMaximumNumberofSharesAllowedtobeIssuedPerPersonPerYear
/ us-gaap_StatementClassOfStockAxis
= us-gaap_RestrictedStockUnitsRSUMember
 
2012 Stock Incentive Plan                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Number of shares authorized                 5,000,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
 
Expiration term   10 years                
2012 Stock Incentive Plan | TBOs                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Stock issued, in shares   135,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_TimedBasedOptionsMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
               
2012 Stock Incentive Plan | PBOs                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Stock issued, in shares   1,250,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
1,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_PerformanceBasedOptionsMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
             
2012 Stock Incentive Plan | Market Based Options                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Per share closing price (in dollars per share)       5.00mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardsMinimumPerShareClosingPriceforVesting
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
           
Number of consecutive trading days   10mpet_MarketBasedStockOptionsNumberofConsecutiveTradingDays
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
  90mpet_MarketBasedStockOptionsNumberofConsecutiveTradingDays
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
           
Median stock price (in dollars per share)   $ 2.35mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardsMedianStockPriceforVesting
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
  5.00mpet_SharebasedCompensationArrangementbySharebasedPaymentAwardsMedianStockPriceforVesting
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
           
Median stock price, maintenance period   90 days                
Stock issued, in shares   400,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
1,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= mpet_StockOptionsMarketBasedMember
/ us-gaap_PlanNameAxis
= mpet_A2012StockIncentivePlanMember
             
Vesting period       3 years            
1998 Stock Incentive Plan                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Number of shares authorized                   288,435us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
Nonvested options outstanding (in shares)   3,131,250us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
               
1998 Stock Incentive Plan | Employee Stock Option                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Market based and performance based shares available for future issuance   658,698us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
               
2015 Incentive Compensation Program | Restricted Stock                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Share-based compensation expense (reversal of expense)   57us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= mpet_A2015IncentiveCompensationProgramMember
               
Former executive | 1998 Stock Incentive Plan                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Number of stock options forfeited/canceled   1,512,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
               
Value of stock repurchased           1,400us-gaap_StockRepurchasedDuringPeriodValue
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
       
Repurchase of common stock   983us-gaap_PaymentsForRepurchaseOfCommonStock
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
      462us-gaap_PaymentsForRepurchaseOfCommonStock
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
       
Former executive officer ownership, percent, more than             5.00%us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
     
Amount of withholding taxes   318us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
               
Shares repurchased during period       1,512,500us-gaap_StockRepurchasedDuringPeriodShares
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
    250,000us-gaap_StockRepurchasedDuringPeriodShares
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
     
Former executive | 1998 Stock Incentive Plan | Employee Stock Option                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Shares repurchased during period             1,512,500us-gaap_StockRepurchasedDuringPeriodShares
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= mpet_A1998StockIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
     
Non-employee Directors                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Number of stock options exercised               21,875us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_TitleOfIndividualAxis
= mpet_NonemployeeDirectorsMember
   
Share-based compensation expense (reversal of expense)   256us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_TitleOfIndividualAxis
= mpet_NonemployeeDirectorsMember
               
Non-employee Directors | Common Stock                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Grants in period               96,330us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_CommonStockMember
/ us-gaap_TitleOfIndividualAxis
= mpet_NonemployeeDirectorsMember
   
Executives | 2015 Incentive Compensation Program | Restricted Stock                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Grants in period   100,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= mpet_A2015IncentiveCompensationProgramMember
/ us-gaap_TitleOfIndividualAxis
= mpet_ExecutiveOfficersMember
               
Chairman of the Board | 2015 Incentive Compensation Program | Restricted Stock                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Grants in period   50,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= mpet_A2015IncentiveCompensationProgramMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_BoardOfDirectorsChairmanMember
               
Selling, General and Administrative Expense                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Share-based compensation expense (reversal of expense)   841us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SellingGeneralAndAdministrativeExpensesMember
1,667us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SellingGeneralAndAdministrativeExpensesMember
             
Selling, General and Administrative Expense | Prior Period Awards                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Share-based compensation expense (reversal of expense)   441us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= mpet_PriorPeriodAwardsMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SellingGeneralAndAdministrativeExpensesMember
               
Selling, General and Administrative Expense | Employee Stock Option                    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Share-based compensation expense (reversal of expense)   $ 561us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SellingGeneralAndAdministrativeExpensesMember