Savings Plans, Pension Plans and Other Postretirement Employee Benefits (Schedule of Estimated Future Benefit Payments) (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Pension Plans [Member]
2021	$ 21,923
2022	22,386
2023	22,649
2024	22,638
2025	22,519
2026–2030	110,216
OPEB [Member]
2021	4,211
2022	3,730
2023	3,556
2024	3,274
2025	3,018
2026–2030	$ 13,300

Amount of benefit for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following current fiscal year.

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

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Amount of benefit for defined benefit plan expected to be paid in next fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in fifth fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in fourth fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in third fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in second fiscal year following current fiscal year.

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