Presentation LIFO Restatement Income Statement (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained Earnings (Accumulated Deficit)	$ 22,993		$ 22,993		$ 21,906
Cost of Goods and Services Sold	33,194	$ 33,342	68,947	$ 66,042
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	1,349	2,266	3,268	4,517
Income Tax Expense (Benefit)	280	211	454	863
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	1,069	2,055	2,814	3,654
Net Income (Loss) Available to Common Stockholders, Basic	$ 1,066	$ 2,047	$ 2,802	$ 3,639
Earnings Per Share, Basic	$ 0.27	$ 0.51	$ 0.70	$ 0.92
Earnings Per Share, Diluted	$ 0.27	$ 0.51	$ 0.70	$ 0.91
Scenario, Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained Earnings (Accumulated Deficit)					21,218
Cost of Goods and Services Sold		$ 33,349		$ 66,057
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		2,259		4,502
Income Tax Expense (Benefit)		209		858
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		2,050		3,644
Net Income (Loss) Available to Common Stockholders, Basic		$ 2,042		$ 3,629
Earnings Per Share, Basic		$ 0.51		$ 0.91
Earnings Per Share, Diluted		$ 0.51		$ 0.91
Scenario, Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained Earnings (Accumulated Deficit)					$ 688	$ 559
Cost of Goods and Services Sold		$ (7)		$ (15)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		7		15
Income Tax Expense (Benefit)		2		5
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		5		10
Net Income (Loss) Available to Common Stockholders, Basic		$ 5		$ 10
Earnings Per Share, Basic		$ 0		$ 0.01
Earnings Per Share, Diluted		$ 0		$ 0