Pension and Postretirement Plans Pension and Postretirement Assumptions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Health care cost trend	8.00%	8.00%
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Rate to which the cost trend is assumed to decline (ultimate trend rate)	4.50%	4.50%
Year the rates reach the ultimate trend rate	2019	2018
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Service and interest costs for 2011	0.2
Service and interest costs for 2011	(0.2)
Postretirement benefit obligation at December 31, 2011	5.9
Postretirement benefit obligation at December 31, 2011	(5.4)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	4.90%	5.50%	6.35%
Expected long-term rate of return on pension and health and life plan assets	8.25%	8.25%	8.25%
Future compensation growth rate	3.00%	3.00%	4.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate	4.50%	5.10%	6.30%
Expected long-term rate of return on pension and health and life plan assets	0.00%	0.00%	8.25%

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

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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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

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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

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

-Topic 715

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- Definition

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

+ References

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- Definition

The effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

+ References

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-Publisher FASB

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- Definition

The effect of a one-percentage- point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

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- Definition

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

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The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

+ References

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

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- Definition

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

+ References

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

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-Name Statement of Financial Accounting Standard (FAS)

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-Glossary Health Care Cost Trend Rate

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- Definition

The ultimate trend rate for health care costs.

+ References

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- Definition

The year when the ultimate health care cost trend rate is expected to be reached.

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