Postretirement Benefits - Schedule of Effect of One-percentage-point Change in Assumed Health Care Cost Trend Rates (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Effect on total of service and interest cost, One-Percentage-Point Increase	$ 6	$ 7
Effect on postretirement benefit obligation, One-Percentage-Point Increase	162	199
Effect on total of service and interest cost, One-Percentage-Point Decrease	(5)	(6)
Effect on postretirement benefit obligation, One-Percentage-Point Decrease	$ (140)	$ (172)

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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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- 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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