Restructuring And Other Charges (Pro Forma Restructuring And Other Charges By Reportable Segments, Pretax) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 281	$ 207	$ 237
Alumina [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	39	12	5
Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	212	145	30
Flat-Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	19	(11)	65
Engineered Products And Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	(3)	18	64
Segment Total [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	267	164	164
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 14	$ 43	$ 73