Contingencies - Tronox Litigation (Detail) - Tronox Litigation [Member] - Judicial Ruling [Member] - USD ($) $ in Millions	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Loss Contingencies [Line Items]
Litigation-related contingent liability	$ 0			$ 5,150		$ 0		$ 5,210
Payment for Tronox settlement		$ 5,200
Litigation-related contingent loss	$ 0		$ 19	$ 4,300	$ 850	$ 5	$ 4,338
Post Settlement Interest Expense [Member]
Loss Contingencies [Line Items]
Litigation-related contingent loss		$ 5						$ 60