Quarterly report pursuant to Section 13 or 15(d)

Preferred Stock (Roll-Forward) (Details)

v2.4.1.9
Preferred Stock (Roll-Forward) (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
6 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Jun. 30, 2014
Amount      
Fiscal year opening balance $ 24,539us-gaap_PreferredStockValueOutstanding    
Current year PIK dividend shares issued 430us-gaap_DividendsPreferredStockPaidinkind 835us-gaap_DividendsPreferredStockPaidinkind  
Balance at end of period 24,969us-gaap_PreferredStockValueOutstanding    
Series A Preferred Stock      
Number of shares      
Fiscal year opening balance 20,089,436us-gaap_PreferredStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
19,239,734us-gaap_PreferredStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
19,239,734us-gaap_PreferredStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
PIK dividend shares issued for previously accrued dividend 0mpet_PreferredStockPaidinKindDividendsIssuedPaidinCash
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
  164,607mpet_PreferredStockPaidinKindDividendsIssuedPaidinCash
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
Current year PIK dividend shares issued 351,565us-gaap_PreferredStockDividendsShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
  685,095us-gaap_PreferredStockDividendsShares
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
Balance at end of period 20,441,001us-gaap_PreferredStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
  20,089,436us-gaap_PreferredStockSharesOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
Amount      
Fiscal year opening balance 24,539us-gaap_PreferredStockValueOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
23,502us-gaap_PreferredStockValueOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
23,502us-gaap_PreferredStockValueOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
PIK dividend shares issued for previously accrued dividend 0mpet_PreferredStockPaidinKindDividendsIssuedPaidinCashAmount
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
  202mpet_PreferredStockPaidinKindDividendsIssuedPaidinCashAmount
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
Current year PIK dividend shares issued 430us-gaap_DividendsPreferredStockPaidinkind
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
  835us-gaap_DividendsPreferredStockPaidinkind
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
Balance at end of period $ 24,969us-gaap_PreferredStockValueOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember
  $ 24,539us-gaap_PreferredStockValueOutstanding
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesAPreferredStockMember