Retirement Benefits (Details 7)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Assumptions Used to Determine Benefit Obligation
Discount rate	4.12%	5.03%
Benefit Obligation \| Pension Benefits
Assumptions Used to Determine Benefit Obligation
Discount rate	4.12%	5.03%
Rate of compensation increase	2.75%	2.75%
Benefit Obligation \| Medical and Life Benefits
Assumptions Used to Determine Benefit Obligation
Discount rate	4.02%	5.02%
Initial health care cost trend rate assumed for the next year	7.00%	7.50%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2017	2017
Assumptions Used to Determine Benefit Cost
Initial health care cost trend rate assumed for the next year	7.00%	7.50%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2017	2017
Benefit Cost \| Pension Benefits
Assumptions Used to Determine Benefit Cost
Discount rate	5.03%	5.75%
Expected long-term return on plan assets	8.25%	8.50%
Rate of compensation increase	2.75%	3.50%
Benefit Cost \| Medical and Life Benefits
Assumptions Used to Determine Benefit Obligation
Initial health care cost trend rate assumed for the next year	7.50%	8.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2017	2017
Assumptions Used to Determine Benefit Cost
Discount rate	5.02%	5.62%
Expected long-term return on plan assets	7.44%	6.86%
Initial health care cost trend rate assumed for the next year	7.50%	8.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2017	2017

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

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph j

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(1)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

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- Definition

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

+ References

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- Definition

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

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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 20

-Section 50

-Paragraph 1

-Subparagraph (k)(3)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 87

-Paragraph 264

-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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph j

-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 4: 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

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

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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.

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The ultimate trend rate for health care costs.

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- Definition

Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

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