Annual report pursuant to Section 13 and 15(d)

Supplemental Oil And Gas Disclosures (Schedule Of Changes In Standardized Measure) (Details)

v2.4.0.6
Supplemental Oil And Gas Disclosures (Schedule Of Changes In Standardized Measure) (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Supplemental Oil And Gas Disclosures [Abstract]      
Standardized measure, beginning of year $ 1,179,072 $ 660,396 $ 761,682
Sales and transfers of oil and gas produced, net of production costs (729,574) (521,551) (386,331)
Net changes in price, net of future production costs 634,174 367,575 (34,841)
Extensions and discoveries, net of future production and development costs 219,924 143,612 98,087
Changes in estimated future development costs (4,572) (59,124) 144,590
Previously estimated development costs incurred 173,911 97,188 224,802
Revisions of quantity estimates 204,988 94,735 (86,600)
Accretion of discount 135,791 68,862 78,789
Net change in income taxes (398,204) (221,226) (32,394)
Purchases of reserves in-place 483,286 624,302 (9,927)
Sales of reserves in-place     (205,691)
Changes in production rates due to timing and other 107,581 (75,697) 108,230
Net increase (decrease) in standardized measure 827,305 518,676 (101,286)
Standardized measure, end of year $ 2,006,377 $ 1,179,072 $ 660,396