Impairment of Proved Properties (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Sep. 30, 2012
Supplemental Income Statement Elements (Textual) [Abstract]
Company recognized an impairment loss	$ 7.6
Estimated fair value	$ 7.7

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This element represents the fair value of assets categorized as other which are not in and of themselves material enough to require separate disclosure.

No definition available.

Name:	us-gaap_OtherAssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant