Annual report pursuant to Section 13 and 15(d)

Acquisitions (Details)

v2.4.0.6
Acquisitions (Details) (USD $)
0 Months Ended 1 Months Ended 12 Months Ended 0 Months Ended 23 Months Ended
Dec. 24, 2012
Feb. 28, 2011
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 21, 2012
Utica Shale [Member]
acre
Dec. 18, 2012
Utica Shale [Member]
Dec. 19, 2012
Utica Shale [Member]
acre
Dec. 31, 2012
Utica Shale [Member]
acre
wells
Dec. 17, 2012
Utica Shale [Member]
acre
Business Acquisition [Line Items]                    
Period allowed for refusal   6 months                
Affiliates participation ratio     50.00%              
Gas and oil areage, undeveloped, net           37,000   7,000 106,000 30,000
Cash price of ownership interest           $ 70,000,000 $ 302,000,000 $ 372,000,000 $ 619,600,000  
Gas and oil areage, undeveloped, gross (acres)                 137,000  
Amount put in escrow               53,900,000    
Number Of Wells Owned                 14  
Proceeds from issuance of common stock, net of offering costs, and exercise of stock options $ 427,900,000   $ 427,091,000 $ 307,154,000 $ 21,879,000