Accounting Standards - Revenue Recognition Standard (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues and other income:
Revenues from contracts with customers	$ 1,447	$ 902	$ 2,984	$ 1,775
Marketing revenues	0	35	0	69
Other income	12	9	16	23
Costs and expenses:
Marketing, including purchases from related parties	0	38	0	72
Shipping, handling and other operating	126	$ 111	256	$ 200
Presentation without adoption of ASC Topic 606 [Member]
Revenues and other income:
Revenues from contracts with customers	1,447		2,982
Marketing revenues	43		75
Other income	11		14
Costs and expenses:
Marketing, including purchases from related parties	44		76
Shipping, handling and other operating	124		251
Accounting Standards Update 2014-09 [Member] | Adjustments [Member]
Revenues and other income:
Revenues from contracts with customers	0		(2)
Marketing revenues	43		75
Other income	(1)		(2)
Costs and expenses:
Marketing, including purchases from related parties	44		76
Shipping, handling and other operating	$ (2)		$ (5)