Accounting Standards Revenue Recognition Standard (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues from contracts with customers	$ 5,902	$ 4,247	$ 2,996
Marketing revenues	0	162	240
Other income	150	78	53
Cost of Purchased Oil and Gas	0	168	245
Shipping, handling and other operating	575	$ 431	$ 484
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues from contracts with customers	(12)
Marketing revenues	159
Other income	(5)
Cost of Purchased Oil and Gas	158
Shipping, handling and other operating	(16)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues from contracts with customers	5,890
Marketing revenues	159
Other income	145
Cost of Purchased Oil and Gas	158
Shipping, handling and other operating	$ 559