Acquisitions and Divestitures - 2017 Divestitures (Details) $ in Millions	1 Months Ended		3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) employee	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Net loss on divestitures of businesses											$ 57	$ 3	$ 136
Sales revenue, goods, net			$ 3,271	$ 3,236	$ 3,261	$ 3,192	$ 2,967	$ 3,138	$ 3,234	$ 3,055	12,960	12,394	12,413
Restructuring and other charges											165	155	$ 214
Slim Aluminium
Business Acquisition [Line Items]
Cash expense related to divestiture of business		$ 10
Guarantee payments to third party		$ 5
Sales revenue, goods, net											$ 54	$ 165
Number of employees | employee											312
Slim Aluminium | Restructuring and Other Charges
Business Acquisition [Line Items]
Net loss on divestitures of businesses											$ 60
Latin America Extrusions (LAE)
Business Acquisition [Line Items]
Proceeds from divestiture of businesses	$ 10
Latin America Extrusions (LAE) | Divested Businesses
Business Acquisition [Line Items]
Restructuring and other charges			$ 41