Acquisitions and Divestitures (Details Textuals) (USD $)	3 Months Ended	9 Months Ended					1 Months Ended			3 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Jun. 01, 2012	Sep. 30, 2012 Petro Harvester [Member]	Mar. 31, 2012 Petro Harvester [Member]	Feb. 29, 2012 Petro Harvester [Member] Petro Harvester Gulf Coast Holdings Llc [Member]	Aug. 31, 2011 Riley Ridge Phase 2 [Member]	Jun. 01, 2012 Thompson Field [Member]	Sep. 30, 2012 Paradox Basin [Member]	Sep. 30, 2012 Bakken Exchange Agreement [Member]	Oct. 31, 2010 Riley Ridge Phase 1 [Member]
Acquisitions and Divestitures (Textuals) [Abstract]
Working interest in business acquisition								57.50%				42.50%
Ownership Interest								57.50%				42.50%
Net proceeds from sales of oil and natural gas properties and equipment		$ 33,973,000	$ 47,598,000				$ 141,800,000			$ 68,500,000
Deferred Riley Ridge acquisition consideration								15,000,000
Pre Adjusted Proceeds From Sale Of Oil And Natural Gas Properties							155,000,000			75,000,000
Business Acquisition, Cost of Acquired Entity, Cash Paid				366,178,000
Effective Date Of Transaction						Dec. 01, 2011			Jun. 01, 2012	Jan. 01, 2012	Jul. 01, 2012
Net working interest acquired in purchase of oil and natural gas properties									nearly 100%
Net revenue interest acquired in purchase of oil and natural gas properties									84.70%
Net Revenue Interest Retained By Seller									5.00%
Oil Production Threshold									3,000
Business Acquisition Purchase Price Allocation Assets Acquired Less Liabilities Assumed				238,949,000
Business Acquisition Goodwill Acquired				127,229,000
Proceeds used in a like-kind exchange	212,500,000
Operating Revenues Net of Capital and Lease Operating Expense Between Effective Date and Closing Date of Sale Transaction					13,500,000
Business Acquisition, Cost of Acquired Entity, Purchase Price								214,800,000
Anticipated Pre Adjusted Cash Proceeds From Sale Of Oil And Natural Gas Properties		$ 1,600,000,000