Retirement Plans, Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost, Other Postretirement Benefits (Details) - Other Postretirement Benefits [Member]	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate	3.50%	4.40%	3.70%
Health care cost trend rate [Abstract]
Initial rate	6.75%	7.00%	7.00%
Ultimate rate	5.00%	5.00%	5.00%
Years to ultimate	2025	2025	2022

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Initial Health Care Cost Trend Rate

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- Definition

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Ultimate Health Care Cost Trend Rate

+ References

No definition available.

+ Details

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- Definition

Year ultimate health care cost trend rate is expected to be reached, in CCYY format.

+ References

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- References

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- References

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