Segment and Geographic Area Information - Schedule of Operating Results and Assets of Alcoa's Reportable Segment (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total sales	$ 27,795	$ 28,777	$ 30,826
Equity income (loss)	(68)	(28)	16
Depreciation, depletion, and amortization	1,337	1,374	1,395
Income taxes	448	535	627
ATOI	1,217	1,357	1,885
Capital expenditures	1,105	1,150
Equity investments	1,775	1,763
Goodwill	2,897	3,898
Total assets	29,247	31,912
Intersegment Sales [Member]
Segment Reporting Information [Line Items]
Intersegment sales	5,034	5,350	6,137
Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	22,761	23,427	24,689
Alumina [Member]
Segment Reporting Information [Line Items]
Total sales	5,561	5,402	6,189
Equity income (loss)	(4)	5	25
Depreciation, depletion, and amortization	426	455	444
Income taxes	66	(27)	179
ATOI	259	90	607
Capital expenditures	322	374
Equity investments	628	658
Goodwill	9	10
Total assets	8,248	9,709
Alumina [Member] | Intersegment Sales [Member]
Segment Reporting Information [Line Items]
Intersegment sales	2,235	2,310	2,727
Alumina [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	3,326	3,092	3,462
Primary Metals [Member]
Segment Reporting Information [Line Items]
Total sales	9,217	10,309	11,432
Equity income (loss)	(51)	(27)	(7)
Depreciation, depletion, and amortization	526	532	556
Income taxes	(74)	106	92
ATOI	(20)	309	481
Capital expenditures	224	318
Equity investments	947	917
Goodwill		997
Total assets	10,341	11,709
Primary Metals [Member] | Intersegment Sales [Member]
Segment Reporting Information [Line Items]
Intersegment sales	2,621	2,877	3,192
Primary Metals [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	6,596	7,432	8,240
Global Rolled Products [Member]
Segment Reporting Information [Line Items]
Total sales	7,284	7,541	7,860
Equity income (loss)	(13)	(6)	(3)
Depreciation, depletion, and amortization	226	229	237
Income taxes	108	159	98
ATOI	252	346	260
Capital expenditures	335	258
Equity investments	200	188
Goodwill	218	214
Total assets	4,647	4,603
Global Rolled Products [Member] | Intersegment Sales [Member]
Segment Reporting Information [Line Items]
Intersegment sales	178	163	218
Global Rolled Products [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	7,106	7,378	7,642
Engineered Products and Solutions [Member]
Segment Reporting Information [Line Items]
Total sales	5,733	5,525	5,345
Equity income (loss)			1
Depreciation, depletion, and amortization	159	158	158
Income taxes	348	297	258
ATOI	726	612	537
Capital expenditures	224	200
Goodwill	2,670	2,677
Total assets	6,011	5,891
Engineered Products and Solutions [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	$ 5,733	$ 5,525	$ 5,345