The cash outflow to purchase of mineral interests in oil and gas properties for use in the normal oil and gas operations and not intended for resale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 15

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3213-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 17

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_PaymentsToAcquireOilAndGasProperty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Commitments and Contingencies (Details) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended
Commitments and Contingencies (Details) (USD $)	Dec. 14, 2011	Jul. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Business Combination, Separately Recognized Transactions [Line Items]
Payments to Acquire Oil and Gas Property		$ 110,000,000	$ 238,854,000	$ 33,075,000	$ 43,726,000
Applicable Asset Group	85,000,000
[SmEnergyLitigationMember]
Loss Contingencies [Line Items]
Loss Contingency Counterclaim Amount			$ 6,000,000	$ 6,000,000
[SmEnergyCompanyMember]
Business Combination, Separately Recognized Transactions [Line Items]
Oil And Gas Business Combination Valuation Of Defects Threshold	15.00%
Termination Date	December 14, 2011