Segment and Geographical Area Information, Financial Information by Operating Segment Table (Details) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010		Dec. 31, 2010
Net Sales:
Total net sales	$ 322.3	[1]	$ 263.4		$ 983.7	[1]	$ 813.3
Segment Operating Income (Loss):
Total operating income (loss)	5.5	[2]	13.2	[2]	41.4	[2]	32.0	[2]
Interest expense	(4.3)		(3.7)		(13.2)		(7.2)
Other income (expense), net	3.9		(3.6)		2.2		(2.7)
Income before income taxes	5.1		5.9		30.4		22.1
Depreciation and Amortization:
Depreciation and amortization	6.2		4.8		18.9		13.8
Capital expenditures:
Capital expenditures	8.8		8.2		22.9		34.9
Income Taxes Paid:
Income taxes paid	0.4		0		1.4		0.3
Segment assets:
Total assets	1,381.3				1,381.3				1,342.4
Fabricated Products [Member]
Net Sales:
Total net sales	322.3		263.4		983.7		813.0
Segment Operating Income (Loss):
Total operating income (loss)	25.8	[3],[4],[5]	5.3	[3],[4],[5]	82.4	[3],[4],[5]	59.6	[3],[4],[5]
Depreciation and Amortization:
Depreciation and amortization	6.2		4.7		18.6		13.6
Capital expenditures:
Capital expenditures	8.7		8.2		22.8		34.0
Segment assets:
Total assets	644.8				644.8				496.7
All Other [Member]
Net Sales:
Total net sales	0		0		0		0.3	[6]
Segment Operating Income (Loss):
Total operating income (loss)	(20.3)	[5],[7]	7.9	[5],[7]	(41.0)	[5],[7]	(27.6)	[5],[7]
Depreciation and Amortization:
Depreciation and amortization	0		0.1		0.3		0.2
Capital expenditures:
Capital expenditures	0.1		0		0.1		0.9
Segment assets:
Total assets	736.5	[8]			736.5	[8]			845.7	[8]
United States [Member]
Income Taxes Paid:
Income taxes paid	0.2		0		1.0		0.2
Canada [Member]
Income Taxes Paid:
Income taxes paid	$ 0.2		$ 0		$ 0.4		$ 0.1

[1] The combined results for the quarter and nine months ended September 30, 2011 are as presented in the Statement of Consolidated Income for such periods, reflecting the January 1, 2011 effective date of the Alexco acquisition (see Note 1).

[2] The Company periodically reassesses the methodologies used to allocate costs among the Company’s business units to assess segment profitability. Commencing the fourth quarter of 2010, the Company modified the allocation of incentive compensation expense relating to its LTI programs and certain STI Plans among its business units. All operating results prior to the fourth quarter of 2010 have been retrospectively adjusted for consistency with the modified cost allocation methodologies. These reclassifications among the Company’s business units had no impact on the Company’s segment or consolidated Net sales, or its consolidated operating income. As a result of the reclassifications, an additional $0.6 and $2.4 of charges relating to the Company’s LTI programs and certain STI Plans are reflected in the operating results of the Fabricated Products segment in the quarter and nine months ended September 30, 2010, respectively.

[3] Operating results in the Fabricated Products segment for the quarters ended September 30, 2011 and September 30, 2010 include environmental expenses of $0.1 and $13.1, respectively. Operating results in the Fabricated Products segment for the nine month periods ended September 30, 2011 and September 30, 2010 include environmental expenses of $0.6 and $13.5, respectively.Fabricated Products segment results for the quarter and nine months ended September 30, 2011 include non-cash mark-to-market losses on natural gas, electricity and foreign currency hedging activities totaling $2.0 and $0.6, respectively. Fabricated Products segment results for the quarter and nine months ended September 30, 2010 include non-cash mark-to-market losses on natural gas and foreign currency hedging activities of $2.4 and $5.2, respectively. For further discussion regarding mark-to-market matters, see Note 11.

[4] Operating results in the Fabricated Products segment for the quarters ended September 30, 2011 and September 30, 2010 included LIFO inventory benefits of $7.1 and $2.0, respectively. Operating results in the Fabricated Products segment for the nine month periods ended September 30, 2011 and September 30, 2010 included LIFO inventory charges of $12.8 and $6.2, respectively.

[5] Operating results of the Fabricated Products segment and All Other include gains and losses on intercompany hedging activities related to metal. At the time the Fabricated Products segment enters into a firm price customer contract, the Hedging business unit and Fabricated Products segment enter into an “internal hedge” so that metal price risk resides in the Hedging business unit under All Other. The Hedging business unit uses third-party hedging instruments to limit exposure to metal-price risks related to firm price customer sales contracts. Results from internal hedging activities between the Fabricated Products segment and Hedging business unit eliminate in consolidation. Internal hedging gains (losses) in the Fabricated Products segment were $2.3 and $(0.8) for the quarters ended September 30, 2011 and September 30, 2010, respectively, and $11.6 and $(2.7) for the nine months ended September 30, 2011 and September 30, 2010, respectively. All Other included the same amounts as (losses) gains for the quarters and nine month periods ended September 30, 2011 and September 30, 2010, respectively.

[6] Net sales in All Other in 2010 represent residual activity involving primary aluminum purchased by the Company from Anglesey while it continued its smelting operations, prior to September 30, 2009, and resold by the Company in the first quarter of 2010. In connection with Anglesey’s new remelt operations beginning in the fourth quarter of 2009, the Company changed its basis of revenue recognition from gross to a net basis (see Note 1).

[7] Operating results of All Other for the quarter and nine months ended September 30, 2011 include non-cash mark-to-market losses on primary aluminum hedging activities totaling $14.8 and $21.4 , respectively. Operating results of All Other for the quarter and nine months ended September 30, 2010 include non-cash mark-to-market gains on primary aluminum hedging activities totaling $17.1 and $1.1, respectively.

[8] Assets in All Other represent primarily all of the Company’s cash and cash equivalents, metal and financial derivative assets, net assets in respect of VEBAs and net deferred income tax assets.