Annual report pursuant to Section 13 and 15(d)

Supplemental Information on Oil and Gas Producing Activities - Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves (Detail)

v2.4.0.8
Supplemental Information on Oil and Gas Producing Activities - Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves (Detail) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves      
Future cash inflows $ 733,761 $ 784,906 $ 636,820
Future production costs (226,681) (206,684) (155,681)
Future development costs (164,142) (186,982) (89,708)
Future income tax expense (155,344) (182,001) (183,233)
Future net cash flows 187,594 209,239 208,198
Discount to present value at 10% annual rate (50,158) (56,337) (42,011)
Standardized measure of discounted future net cash flows 137,436 152,902 166,187
United States
      
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves      
Future cash inflows 8,276 8,260 13,274
Future production costs (3,038) (3,194) (1,661)
Future development costs     (4,180)
Future income tax expense (825) (807) (1,347)
Future net cash flows 4,413 4,259 6,086
Discount to present value at 10% annual rate (1,299) (1,028) (3,150)
Standardized measure of discounted future net cash flows 3,114 3,231 2,936
Gabon
      
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves      
Future cash inflows 725,485 776,646 623,546
Future production costs (223,643) (203,490) (154,020)
Future development costs (164,142) (186,982) (85,528)
Future income tax expense (154,519) (181,194) (181,886)
Future net cash flows 183,181 204,980 202,112
Discount to present value at 10% annual rate (48,859) (55,309) (38,861)
Standardized measure of discounted future net cash flows $ 134,322 $ 149,671 $ 163,251