Annual report pursuant to Section 13 and 15(d)

Supplemental Information On Oil And Gas Exploration And Production Activities (Capitalized Costs Related To Oil And Gas Producing Activities) (Details)

v2.4.0.6
Supplemental Information On Oil And Gas Exploration And Production Activities (Capitalized Costs Related To Oil And Gas Producing Activities) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2012
Dec. 31, 2011
Oil and Gas Exploration and Production Industries Disclosures [Abstract]    
Proven properties $ 984,795 $ 897,130
Unproven properties 626,295 132,912
Gross capitalized costs 1,611,090 1,030,042
Accumulated depreciation, depletion, amortization and impairment reserve (661,442) (571,213)
Net capitalized costs $ 949,648 $ 458,829