Presentation LIFO Restatement Income Statement (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained Earnings (Accumulated Deficit)	$ 23,384		$ 23,384		$ 21,906
Cost of Goods and Services Sold	31,568	$ 30,275	100,515	$ 96,317
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	1,094	1,770	4,362	6,287
Income Tax Expense (Benefit)	101	191	555	1,054
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	993	1,579	3,807	5,233
Net Income (Loss) Available to Common Stockholders, Basic	$ 991	$ 1,572	$ 3,793	$ 5,211
Earnings Per Share, Basic	$ 0.25	$ 0.40	$ 0.95	$ 1.31
Earnings Per Share, Diluted	$ 0.25	$ 0.39	$ 0.95	$ 1.30
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		$ 30,288		$ 96,345
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		1,757		6,259
Income Tax Expense (Benefit)		186		1,044
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		1,571		5,215
Net Income (Loss) Available to Common Stockholders, Basic		$ 1,564		$ 5,193
Earnings Per Share, Basic		$ 0.39		$ 1.31
Earnings Per Share, Diluted		$ 0.39		$ 1.30
Scenario, Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained Earnings (Accumulated Deficit)					$ 688	$ 559
Cost of Goods and Services Sold		$ (13)		$ (28)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		13		28
Income Tax Expense (Benefit)		5		10
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		8		18
Net Income (Loss) Available to Common Stockholders, Basic		$ 8		$ 18
Earnings Per Share, Basic		$ 0.01		$ 0
Earnings Per Share, Diluted		$ 0		$ 0