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Pension and Postretirement Health and Life Benefits (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Curtailment (gains)	$ 0.7
Decrease in pension liability, curtailments	138.3
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.92%		4.92%		4.07%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	4.00%		4.00%		4.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	6.75%				6.75%
Net defined benefit plan costs for former Portsmouth employees		3.3	7.5	9.9
Defined Contribution Plan, Employer Matching Contribution, Percent	7.00%		4.00%
Defined Benefit Pension Plans [Member]
Expected defined benefit plan contributions for current fiscal year			24.1
Expected defined benefit plan contributions for current fiscal year under ERISA	20.9		20.9
Expected defined benefit plan contributions for current fiscal year for non-qualified plans	2.5		2.5
USEC contributions			16.2
Curtailment (gains)	$ 0		$ 0.7

X

- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(1)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

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- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Expected Long-Term Rate of Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512013



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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

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- Definition

The amount of decrease that is related to an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services.

+ References

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-Topic 715

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The amount of net gain (loss) recognized in net periodic benefit cost as a result of an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services.

+ References

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- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan in the current remaining fiscal period.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Expected defined benefit plan contributions for current fiscal year for non-qualified plans

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Expected defined benefit plan contributions for current fiscal year under ERISA

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Net Defined Benefit Plan Costs For Former Portsmouth Employees charged directly to cost of sales.

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