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Charge to cost of goods sold that represents the reduction of the carrying amount of inventory, generally attributable to obsolescence or market conditions.

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Transition Charges (Narrative)(Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Restructuring Cost and Reserve [Line Items]
Asset Retirement Charges			$ 19.3
Inventory Valuation Adjustments	5.0		15.0
Non-production expenses	47.7	6.1	123.4	12.7
Site expenses	37.4		63.8
Power Contract Losses			11.8
Accelerated property, plant and equipment expenses	5.3	2.8	13.5	2.8
Net defined benefit plan costs for former Portsmouth employees		3.3	7.5	9.9
One-time termination benefit costs	1.5	0.4	3.6	4.0
DOE Share of Paducah Termination Benefit Costs	6.0
Structuring advisory costs	2.0	1.1	6.7	7.1
Curtailment (gains)	0.7
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated Total Paducah Termination Benefit Costs	23
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated Total Paducah Termination Benefit Costs	27
Uranium Market Conditions [Member]
Restructuring Cost and Reserve [Line Items]
Inventory Valuation Adjustments			5.0
Residual Uranium [Member]
Restructuring Cost and Reserve [Line Items]
Inventory Valuation Adjustments			7.7
Materials and Supplies [Member]
Restructuring Cost and Reserve [Line Items]
Inventory Valuation Adjustments			2.3
Workforce Reduction Phase One [Member]
Restructuring Cost and Reserve [Line Items]
One-time termination benefit costs			2.0
Payments for one-time termination benefits			2.5
DOE Share of Paducah Termination Benefit Costs			0.7
Workforce Reduction Phase Two [Member]
Restructuring Cost and Reserve [Line Items]
One-time termination benefit costs	1.6
DOE Share of Paducah Termination Benefit Costs	0.5
Workforce Reduction Phase Two [Member] \| Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated Near-Term Termination Benefit Costs	1.6
Workforce Reduction Phase Two [Member] \| Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Estimated Near-Term Termination Benefit Costs	$ 2.4