Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Goodwill [Roll Forward]
Goodwill gross, beginning balance		$ 5,201	$ 5,302
Accumulated impairment losses, beginning balance		(53)	(53)
Goodwill, beginning balance		5,148	5,249
Acquisitions and Divestitures			47
Impairment		(719)	0	$ (25)
Translation and other		106	(148)
Goodwill gross, ending balance	$ 5,307	5,307	5,201	5,302
Accumulated impairment losses, ending balance	(772)	(772)	(53)	(53)
Goodwill, ending balance	4,535	$ 5,148	5,249	5,249
Number of reportable segments | segment		3
Engineered Products and Solutions
Goodwill [Roll Forward]
Impairment	(719)	$ (719)
Segment reporting, goodwill	256
Global Rolled Products
Goodwill [Roll Forward]
Segment reporting, goodwill	59
Transportation and Construction Solutions
Goodwill [Roll Forward]
Impairment				(25)
Segment reporting, goodwill	18
Operating Segments | Engineered Products and Solutions
Goodwill [Roll Forward]
Goodwill gross, beginning balance		4,579	4,660
Accumulated impairment losses, beginning balance		0	0
Goodwill, beginning balance		4,579	4,660
Acquisitions and Divestitures			47
Impairment		(719)
Translation and other		89	(128)
Goodwill gross, ending balance	4,668	4,668	4,579	4,660
Accumulated impairment losses, ending balance	(719)	(719)	0	0
Goodwill, ending balance	3,949	4,579	4,660	4,660
Operating Segments | Global Rolled Products
Goodwill [Roll Forward]
Goodwill gross, beginning balance		181	201
Accumulated impairment losses, beginning balance		0	0
Goodwill, beginning balance		181	201
Acquisitions and Divestitures			0
Impairment		0
Translation and other		12	(20)
Goodwill gross, ending balance	193	193	181	201
Accumulated impairment losses, ending balance	0	0	0	0
Goodwill, ending balance	193	181	201	201
Operating Segments | Transportation and Construction Solutions
Goodwill [Roll Forward]
Goodwill gross, beginning balance		110	111
Accumulated impairment losses, beginning balance		(53)	(53)
Goodwill, beginning balance		57	58
Acquisitions and Divestitures			0
Impairment		0
Translation and other		3	(1)
Goodwill gross, ending balance	113	113	110	111
Accumulated impairment losses, ending balance	(53)	(53)	(53)	(53)
Goodwill, ending balance	60	57	58	58
Corporate
Goodwill [Roll Forward]
Goodwill gross, beginning balance		331	330
Accumulated impairment losses, beginning balance		0	0
Goodwill, beginning balance		331	330
Acquisitions and Divestitures			0
Impairment		0
Translation and other		2	1
Goodwill gross, ending balance	333	333	331	330
Accumulated impairment losses, ending balance	0	0	0	0
Goodwill, ending balance	$ 333	$ 331	$ 330	$ 330