Segment Disclosures and Related Information (Summary of Geographic Information) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Analysis of results of sales and other operating revenues and long-lived assets by geographical location [Abstract]
Sales and other operating revenues	[1],[2]	$ 98,975	$ 161,212	$ 171,596
Long-Lived Assets	[3]	31,701	27,384	26,478
United States [Member]
Analysis of results of sales and other operating revenues and long-lived assets by geographical location [Abstract]
Sales and other operating revenues	[2]	69,578	110,713	115,378
Long-Lived Assets	[3]	29,624	25,255	23,641
United Kingdom [Member]
Analysis of results of sales and other operating revenues and long-lived assets by geographical location [Abstract]
Sales and other operating revenues	[2]	12,120	20,131	21,868
Long-Lived Assets	[3]	1,459	1,469	1,485
Germany [Member]
Analysis of results of sales and other operating revenues and long-lived assets by geographical location [Abstract]
Sales and other operating revenues	[2]	6,584	9,424	9,799
Long-Lived Assets	[3]	502	534	587
Other foreign countries [Member]
Analysis of results of sales and other operating revenues and long-lived assets by geographical location [Abstract]
Sales and other operating revenues	[2]	10,693	20,944	24,551
Long-Lived Assets	[3]	$ 116	$ 126	$ 765

[1] Includes excise taxes on petroleum products sales: $13,780 million, $14,698 million, $13,866 million

[2] Sales and other operating revenues are attributable to countries based on the location of the operations generating the revenues.

[3] Defined as net properties, plants and equipment plus investments in and advances to affiliated companies.