Restructuring and Other Charges - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($) employee position	Jun. 30, 2017 USD ($) position	Jun. 30, 2018 USD ($) employee position	Jun. 30, 2017 USD ($) position	Dec. 31, 2017 USD ($) employee
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 15	$ 26	$ 22	$ 99
Restructuring and other charges after tax and noncontrolling interest	12	$ 17	$ 17	$ 86
Number of employees associated with layoff costs | position		352	40	680
Reversal of forfeited executive stock compensation		$ 13		$ 13
Severance costs		$ 7		7
Cash payments made against the layoff reserves			$ 30		$ 65
New York office
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	5		5
Restructuring and other charges after tax	$ 4		$ 4
Fusina, Italy
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges				60
Restructuring and other charges after tax				$ 60
Corporate
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | position		20	16	62
Engineered Products and Solutions
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | position	24	129	24	243
Global Rolled Products
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | position		110		242
Transportation and Construction Solutions
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | position		93		133
Pension Curtailment Charge
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 9		$ 14
Restructuring and other charges after tax	7		11
Restructuring Programs Layoffs
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	4	$ 29	8	$ 48
Restructuring and other charges after tax	3	19	6	32
Other Miscellaneous Items
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	2	4	4	1
Restructuring and other charges after tax	2	3	3	0
Other Adjustments
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	5	1	9	2
Restructuring and other charges after tax and noncontrolling interest	$ 4	1	$ 7	2
Reversal of Forfeited Executive Stock Compensation
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		6		6
Restructuring and other charges after tax		$ 4		$ 4
Restructuring Programs Layoffs 2018
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee			40
Approximate number of employees already laid off | employee	20		20
Cash payments made against the layoff reserves	$ 2		$ 3
Restructuring Programs Layoffs 2017
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs | employee			760		830
Approximate number of employees already laid off | employee	530		530
Cash payments made against the layoff reserves	$ 8		$ 23
Restructuring Programs Layoffs 2016
Restructuring Cost and Reserve [Line Items]
Cash payments made against the layoff reserves	$ 0		$ 4