Pensions and Postretirement Benefits (Summary of One-Percentage-Point Change in Assumed Healthcare Cost Trend Rate) (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Summary of One-Percentage-Point Change in the Assumed Healthcare Cost Trend Rate
Effect on total of service and interest cost components in 2017 increase	$ 0.0
Effect on total of service and interest cost components in 2017 decrease	0.0
Effect on postretirement benefit obligation as of December 31, 2017 increase	0.5
Effect on postretirement benefit obligation as of December 31, 2017 decrease	$ (0.4)

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (m)
-URI http://asc.fasb.org/extlink&oid=118255775&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

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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

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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

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