Assets Held for Sale and Discontinued Operations - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Discontinued Operations And Disposal Groups [Abstract]
Accrued liabilities		$ 3,500
Impairment of proved oil and gas properties	$ 6,849

Disposal group including discontinued operation impairment of proved oil and natural gas properties.

No definition available.

Name:	mr_DisposalGroupIncludingDiscontinuedOperationImpairmentOfProvedOilAndNaturalGasProperties
Namespace Prefix:	mr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration