Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Weighted-Average Useful Lives of Structures and Machinery and Equipment

The following table details the weighted-average useful lives of structures and machinery and equipment by reporting segment (numbers in years):

Segment	Structures		Machinery and equipment
Alumina:
Alumina refining		30		26
Bauxite mining		31		17
Primary Metals:
Aluminum smelting		35		21
Power generation		30		21
Global Rolled Products		32		21
Engineered Products and Solutions		29		18

Weighted-Average Useful Lives of Software and Other Intangible Assets

 The following table details the weighted-average useful lives of software and other intangible assets by reporting segment (numbers in years):

Segment	Software		Other intangible assets
Alumina		10		34
Primary Metals		8		39
Global Rolled Products		9		17
Engineered Products and Solutions		11		19