Benefit Plans - Effects of One-Percentage-Point Change in Assumed Healthcare Cost Trend Rates (Details) - Maximum $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate [Abstract]
Effect on the net periodic benefit cost - 1% increase	$ 0.1
Effect on the net periodic benefit cost - 1% decrease	0.1
Effect on the postretirement benefit obligation - 1% increase	0.1
Effect on the postretirement benefit obligation - 1% decrease	$ 0.1

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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/otherTransitionRef
-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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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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