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Property, Plant and Equipment (Narrative) (Details) (USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Property, Plant and Equipment
Capital expenditures for American Centrifuge Project	$ 1,213.9	$ 1,143.8
Capitalized asset retirement obligations	19.3	19.3
Expensed centrifuge machines	9.6
Upper range of potential future expense for centrifuge machine disposal	$ 100.0

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Cumulative capital expenditures for American Centrifuge Project

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Capitalized asset retirement obligations

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Expensed centrifuge machines

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Potential future expense of centrifuge machine disposal

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