Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2011

Summary Of Significant Accounting Policies [Abstract]

Weighted-Average Useful Lives Of Structures And Machinery And Equipment

Segment	Structures		Machinery and equipment
Alumina		29		25
Primary Metals		34		21
Flat-Rolled Products		31		21
Engineered Products and Solutions		27		18

Weighted-Average Useful Lives Of Software And Other Intangible Assets

Segment	Software		Other intangible assets
Alumina		10		-
Primary Metals		10		40
Flat-Rolled Products		9		10
Engineered Products and Solutions		9		17