Advanced Technology Costs and Other Income (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Research and Development [Abstract]
Maximum funding for RD&D Program			$ 350
RD&D Program Funding by DOE			80.00%
RD&D Program Funding by USEC			20.00%
Maximum RD&D Program Funding by DOE			280
Maximum RD&D Program Funding by USEC			70
RD&D Program Funding by DOE To Date			227.7
RD&D Program Funding by DOE - Increment 1			87.7
RD&D Program Funding by DOE - Increment 2			45.7
RD&D Program Funding by DOE - Increment 3			44.4
RD&D Program Funding by DOE - Increment 4			49.9
RD&D Program Qualifying Expenditures To Date	225.5		225.5
RD&D Program Qualifying Expenditures To Date - DOE Share	180.4		180.4
RD&D Program Qualifying Expenditures To Date - DOE Share - Received	156.2		156.2
RD&D Program Qualifying Expenditures To Date - DOE Share - Receivable	24.2	4.4	24.2	4.4
RD&D Program Funding - DOE Advance	21.7		21.7		2.4
RD&D Program Qualifying Expenditures	50.9		110.4
RD&D Program Qualifying Expenditures - DOE Share	40.7	10.0	88.3	10.0
RD&D Program Funding by DOE Remaining			52.3
RD&D Program Funding by DOE Remaining - Government Requested			$ 48.0