Contingencies and Commitments - Summary of Activity Related to Alba Matter (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commitments Contingencies And Litigation [Line Items]
Government investigations	$ 782	$ 172	$ 281
Civil suit	19,286	20,401	20,480
(Loss) income from continuing operations before income taxes	(1,816)	324	1,063
Benefit for income taxes	428	162	255
Net (loss) income	(2,244)	162	805
Alba [Member]
Commitments Contingencies And Litigation [Line Items]
(Loss) income from continuing operations before income taxes	384	85
Benefit for income taxes	66	18
Net (loss) income	318	67
Alba [Member] | Government Investigation [Member]
Commitments Contingencies And Litigation [Line Items]
Government investigations	384
Alba [Member] | Civil Suit [Member]
Commitments Contingencies And Litigation [Line Items]
Civil suit		85
Alcoa [Member] | Alba [Member]
Commitments Contingencies And Litigation [Line Items]
Reallocation of civil suit	21
Reallocation of legal costs	20
(Loss) income from continuing operations before income taxes	367	51
Benefit for income taxes	66	18
Net (loss) income	301	33
Alcoa [Member] | Alba [Member] | Government Investigation [Member]
Commitments Contingencies And Litigation [Line Items]
Government investigations	326
Alcoa [Member] | Alba [Member] | Civil Suit [Member]
Commitments Contingencies And Litigation [Line Items]
Civil suit		51
Alumina [Member] | Alba [Member]
Commitments Contingencies And Litigation [Line Items]
Reallocation of civil suit	(21)
Reallocation of legal costs	(20)
(Loss) income from continuing operations before income taxes	17	34
Net (loss) income	17	34
Alumina [Member] | Alba [Member] | Government Investigation [Member]
Commitments Contingencies And Litigation [Line Items]
Government investigations	58
Alumina [Member] | Alba [Member] | Civil Suit [Member]
Commitments Contingencies And Litigation [Line Items]
Civil suit		$ 34