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Pension Plan and Other Postretirement Benefits - Weighted-average Assumptions Used to Determine Benefit Obligations (Details)	Dec. 31, 2020	Dec. 31, 2019
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	2.78%	3.47%
Pension Plan | Participants to Age 39
Defined Benefit Plan Disclosure [Line Items]
Rate of Increase in Future Compensation Level:	4.50%	4.50%
Pension Plan | Participants Age 40 to Age 49
Defined Benefit Plan Disclosure [Line Items]
Rate of Increase in Future Compensation Level:	3.50%	3.50%
Pension Plan | Participants Age 50 and Older
Defined Benefit Plan Disclosure [Line Items]
Rate of Increase in Future Compensation Level:	2.75%	2.75%
Executive Survivor and Supplemental Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	2.61%	3.36%
Rate of Increase in Future Compensation Level:	3.00%	3.50%
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	2.75%	3.43%

X

- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation 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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X

- Definition

Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related 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)(2)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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