Operating Segments and Geographic Data (Details 1) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	[1]
Segment Assets
Goodwill	$ 4,588	$ 4,593
Total Assets	266,103	266,026
United States [Member]
Segment Assets
Total Assets	72,891	79,014
International [Member]
Segment Assets
Total Assets	188,624	182,419
Operating Segments [Member]
Segment Assets
Total Assets	250,602	247,463
Operating Segments [Member] | Upstream [Member]
Segment Assets
Goodwill	4,588	4,593
Total Assets	214,212	206,672
Operating Segments [Member] | Upstream [Member] | United States [Member]
Segment Assets
Total Assets	46,407	49,343
Operating Segments [Member] | Upstream [Member] | International [Member]
Segment Assets
Total Assets	163,217	152,736
Operating Segments [Member] | Downstream [Member]
Segment Assets
Total Assets	36,390	40,791
Operating Segments [Member] | Downstream [Member] | United States [Member]
Segment Assets
Total Assets	21,408	23,068
Operating Segments [Member] | Downstream [Member] | International [Member]
Segment Assets
Total Assets	14,982	17,723
Corporate, Non-Segment [Member]
Segment Assets
Total Assets	15,501	18,563
Corporate, Non-Segment [Member] | United States [Member]
Segment Assets
Total Assets	5,076	6,603
Corporate, Non-Segment [Member] | International [Member]
Segment Assets
Total Assets	$ 10,425	$ 11,960

[1] 2014 conformed to 2015 presentation