Other Income, Net - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Non operating Income Expense [Line Items]
Net loss (gain) from asset sales	$ 156	$ 74	$ 47
Firth Rixson [Member]
Other Non operating Income Expense [Line Items]
Other, net	76
Sherwin, TX Site [Member]
Other Non operating Income Expense [Line Items]
Net loss (gain) from asset sales		19
China Rolling Mill Equity Investment [Member]
Other Non operating Income Expense [Line Items]
Net loss (gain) from asset sales		$ 19	$ 14
Post Closing Adjustment [Member] \| Firth Rixson [Member]
Other Non operating Income Expense [Line Items]
Other, net	(20)
Contingent Consideration Earn Out Liability [Member] \| Firth Rixson [Member]
Other Non operating Income Expense [Line Items]
Other, net	$ (56)