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Property, Plant and Equipment (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2011 | Jun. 30, 2011 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
Property, Plant and Equipment |  |  |  |  |
Capital expenditures for American Centrifuge Project | $ 1,119.0 |  | $ 1,119.0 | $ 1,143.8 |
Interest costs capitalized during period |  |  | 33.4 | 31.6 | 22.9
Capitalized asset retirement obligations | 19.3 |  | 19.3 |  |
Expensed centrifuge machines | 127.1 | 9.6 |  |  |
ACP spending reduction in October 2011 |  |  | 30.00% |  |
Upper range of potential ACP asset impairment expense |  |  | $ 1,100.0 |  |

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- Definition The amount of interest that was capitalized during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 34 -Paragraph 21 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391 + Details
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