Annual report pursuant to Section 13 and 15(d)

Supplemental Information on Oil and Gas Producing Activities (Details 4)

v2.4.0.6
Supplemental Information on Oil and Gas Producing Activities (Details 4) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves      
Future cash inflows $ 784,906 $ 636,820 $ 517,458
Future production costs (206,684) (155,681) (140,673)
Future development costs (186,982) (89,708) (71,190)
Future income tax expense (182,001) (183,233) (159,845)
Future net cash flows 209,239 208,198 145,750
Discount to present value at 10% annual rate (56,337) (42,011) (20,926)
Standardized measure of discounted future net cash flows 152,902 166,187 124,824
United States [Member]
      
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves      
Future cash inflows 8,260 13,274 407
Future production costs (3,194) (1,661) (203)
Future development costs   (4,180)  
Future income tax expense (807) (1,347) (34)
Future net cash flows 4,259 6,086 170
Discount to present value at 10% annual rate (1,028) (3,150) (41)
Standardized measure of discounted future net cash flows 3,231 2,936 129
International [Member]
      
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves      
Future cash inflows 776,646 623,546 517,051
Future production costs (203,490) (154,020) (140,470)
Future development costs (186,982) (85,528) (71,190)
Future income tax expense (181,194) (181,886) (159,811)
Future net cash flows 204,980 202,112 145,580
Discount to present value at 10% annual rate (55,309) (38,861) (20,885)
Standardized measure of discounted future net cash flows $ 149,671 $ 163,251 $ 124,695