Employee Benefit Plans (One Percentage-Point Change Effects) (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($)
Summary of one percentage-point change in assumed healthcare cost trend rate
Effect of one percentage point increase on total of service and interest cost	$ 0.0
Effect of one percentage point decrease on total of service and interest cost	0.0
Effect of one percentage point increase on the postretirement benefit obligation	0.1
Effect of one percentage point decrease on the postretirement benefit obligation	$ (0.1)

No definition available.

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- Definition

Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate.

+ 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 (m)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

+ Details

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- Definition

Amount of decrease in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point decrease in assumed health care cost trend rate.

+ References

+ Details

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- Definition

Amount of increase in accumulated postretirement benefit obligation from one-percentage-point increase in assumed health care cost trend rate.

+ References

+ Details

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- Definition

Amount of increase in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point increase in assumed health care cost trend rate.

+ References

+ Details

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