Business Segments - Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total direct international sales	$ 1,585.1	$ 1,705.7	$ 1,709.4
Sales by U.S. operations to foreign countries	1,175.1	1,262.9	1,313.9
Closed company and other expense	14.2	18.5	9.9
Closed companies environmental costs	3.9	4.3	4.9
Other corporate expense	10.3	10.2	5.0
Closed companies real estate costs		4.0
Former Engineered Products Segment [Member]
Segment Reporting Information [Line Items]
Percent of total revenue	3.00%
Flat-Rolled Products [Member]
Segment Reporting Information [Line Items]
Income (loss) from equity method investments	(7.1)	4.9	7.4
Inventory valuation reserves	20.5
Flat-Rolled Products and High Performance Metals [Member]
Segment Reporting Information [Line Items]
Inventory valuation reserves	55.5
High Performance Metals [Member]
Segment Reporting Information [Line Items]
Inventory valuation reserves	35.0
Corporate Joint Venture [Member]
Segment Reporting Information [Line Items]
Equity method investment ownership percentage	50.00%
Revenue from related parties	$ 95.9	$ 77.1	$ 149.1
STAL Precision Stainless Steel Company Limited [Member]
Segment Reporting Information [Line Items]
Joint venture ownership percentage	60.00%

total foreign country sales from domicile operations

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Environmental costs for closed operations

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Real estate related costs for closed operations

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Other expenses including closed companies expenses

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Revenues from external customers attributed to all foreign countries in total from which the entity derives revenues.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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