v2.4.0.6
Supplemental Information On Oil And Gas Operations (Standardized Measure Of Discounted Future Net Cash Flows Related To Interest In Proved Reserves) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
United States [Member]
      
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]      
Future cash flows $ 69,305 $ 58,093 $ 44,571
Future costs development (6,817) (6,220) (6,814)
Future costs production (26,217) (24,223) (22,184)
Future income tax expense (11,432) (8,643) (3,572)
Future net cash flows 24,839 19,007 12,001
10% discount to reflect timing of cash flows (13,492) (10,164) (6,121)
Standardized measure of discounted future net cash flows 11,347 8,843 5,880
Canada [Member]
      
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]      
Future cash flows 36,786 35,948 28,442
Future costs development (4,678) (4,526) (4,132)
Future costs production (15,063) (12,249) (9,847)
Future income tax expense (3,763) (4,209) (3,408)
Future net cash flows 13,282 14,964 11,055
10% discount to reflect timing of cash flows (6,785) (7,455) (5,532)
Standardized measure of discounted future net cash flows 6,497 7,509 5,523
North America [Member]
      
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]      
Future cash flows 106,091 94,041 73,013
Future costs development (11,495) (10,746) (10,946)
Future costs production (41,280) (36,472) (32,031)
Future income tax expense (15,195) (12,852) (6,980)
Future net cash flows 38,121 33,971 23,056
10% discount to reflect timing of cash flows (20,277) (17,619) (11,653)
Standardized measure of discounted future net cash flows $ 17,844 $ 16,352 $ 11,403