XML 29 R78.htm IDEA: XBRL DOCUMENT v2.4.0.6
Supplementary Oil and Natural Gas Disclosures (Unaudited) (Schedule of Changes in Standardized Measure of Discounted Future Net Cash Flows Applicable to Proved Oil and Natural Gas Reserves) (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Supplementary Oil and Natural Gas Disclosures (Unaudited) [Abstract]    
Beginning of the period $ 876,169 $ 359,458
Sales and transfers of oil and natural gas produced, net of productuin costs (317,059) (266,120)
Net changes in prices and prooduction costs (244,824) 461,719
Purchase of mineral in place 797,085 230,471
Extensions, discoveries and improved recoveries, net of future production costs 452,258 139,757
Revision of quantity estimates 55,133 54,329
Previously estimated development costs incurred during the period 39,321 27,066
Changes in estimated future development costs 746 24,662
Changes in production rates (timing) and other (14,157) (25,655)
Accretion of discount 110,070 41,307
Net change in income taxes (180,460) (170,825)
Net increase (decrease) 698,113 516,711
End of period $ 1,574,282 $ 876,169