Restructuring And Other Charges (Schedule Of Restructuring And Other Charges By Reportable Segments, Pretax) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 10	$ 6
Alumina [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		1
Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	5	2
Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	1	2
Engineered Products And Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	3
Segment Total [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	9	5
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 1	$ 1