Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Details)

v2.4.1.9
Stockholders' Equity (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 6 Months Ended 12 Months Ended 0 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Jun. 30, 2014
Jul. 01, 2014
Oct. 10, 2014
Class of Stock [Line Items]          
Shares of common stock repurchased 1,512,500us-gaap_StockRepurchasedDuringPeriodShares        
Repurchase of common stock $ 566us-gaap_PaymentsForRepurchaseOfCommonStock $ 0us-gaap_PaymentsForRepurchaseOfCommonStock      
Treasury Stock [Roll Forward]          
Fiscal year opening balance (in shares) 9,425,114us-gaap_TreasuryStockShares 9,414,176us-gaap_TreasuryStockShares 9,414,176us-gaap_TreasuryStockShares 9,425,114us-gaap_TreasuryStockShares  
Fiscal year opening balance 9,344us-gaap_TreasuryStockValue 9,333us-gaap_TreasuryStockValue 9,333us-gaap_TreasuryStockValue 9,344us-gaap_TreasuryStockValue  
Shares repurchased from former executive (in shares) 250,000us-gaap_TreasuryStockSharesAcquired        
Shares repurchased from former executive 462us-gaap_TreasuryStockValueAcquiredCostMethod        
Net shares repurchased for employee tax and option exercise price obligations related to the vesting of restricted stock and the exercise of employee stock options (in shares) 47,920us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation   10,938us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation    
Net shares repurchased for employee tax and option exercise price obligations related to the vesting of restricted stock and the exercise of employee stock options 104us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation   11us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation    
Cancellation of shares repurchased (in shares) (47,920)us-gaap_TreasuryStockSharesRetired   0us-gaap_TreasuryStockSharesRetired    
Cancellation of shares repurchased (104)us-gaap_TreasuryStockRetiredCostMethodAmount   0us-gaap_TreasuryStockRetiredCostMethodAmount    
Balance at end of period (in shares) 9,675,114us-gaap_TreasuryStockShares   9,425,114us-gaap_TreasuryStockShares    
Balance at end of period $ 9,806us-gaap_TreasuryStockValue   $ 9,344us-gaap_TreasuryStockValue    
Restricted Stock          
Class of Stock [Line Items]          
Vested restricted stock award (in shares)       150,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		 
Treasury Stock [Roll Forward]          
Net shares repurchased for employee tax and option exercise price obligations related to the vesting of restricted stock and the exercise of employee stock options (in shares)       47,920us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		 
Former Company Executive          
Class of Stock [Line Items]          
Shares of common stock repurchased from individual retirement account         250,000mpet_StockRepurchasedfromIndividualRetirementAccountDuringPeriodShares
/ us-gaap_TitleOfIndividualAxis
= mpet_FormerCompanyExecutiveMember