Supplemental Disclosures about Oil and Natural Gas Producing Properties (unaudited) - Narrative (Details) - USD ($)	12 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Reserve Quantities [Line Items]
Oil and natural gas property costs attributable to the recognition of asset retirement obligations	$ 576,039	$ 66,976	$ 65,575
Period Considered for Unweighted Arithmetic Average for Determining Reserve Volumes and Values	12 months
Period Considered for Determining Unweighted Arithmetic Average of First Day of Month, Commodity Prices	12 months

Amount of asset retirement obligations incurred during the period, net of certain increases or decreases in the amount of the asset retirement obligation during the current period that may include changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

No definition available.

Name:	epm_AssetRetirementObligationLiabilitiesIncurredNet
Namespace Prefix:	epm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration