Retirement Benefits One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Pension and Other Postretirement Benefit Expense [Abstract]
Effect on total of service and interest cost, one percentage point increase	$ 0.1
Effect on total of service and interest cost, one percentage point decrease	(0.1)
Effect of on postretirement benefit obligation, one percentage point increase	1.5
Effect on postretirement benefit obligation, one percentage point decrease	$ (1.5)

Amount of 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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (m)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

+ Details

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- Definition

Amount of 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

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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.

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- Definition

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.

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