Acquisitions and Divestitures (Assets Acquired and Liability Assumed - Alcan Cable China) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010	Dec. 03, 2012 CHINA [Member] Alcan Cable [Member]
Business Acquisition [Line Items]
Cash						$ 8.4
Accounts receivable						8.5
Inventories						20.5
Property, plant, and equipment						58.8
Intangible assets						0
Goodwill	187.6	[1]	171.4	[1]	178.5	0
Other current and noncurrent assets						0.2
Total Assets						96.4
Current liabilities						18.6
Other liabilities						20.1
Total liabilities						$ 38.7

[1] See Note 23 - Restatement of Consolidated Financial Statements