Noncontrolling Interests - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Noncontrolling Interest [Line Items]
Proceeds from noncontrolling shareholder	$ 12	$ 171	$ 169
Charges related to legal matters included in noncontrolling interests	391	85
Noncontrolling Interests [Member]
Noncontrolling Interest [Line Items]
Proceeds from noncontrolling shareholder	12	171	169
Charges related to legal matters included in noncontrolling interests	17	34
Alumina Limited [Member]
Noncontrolling Interest [Line Items]
Proceeds from noncontrolling shareholder	$ 9	$ 171	$ 169