Employee Benefit Plans (Schedule of Effect of One-percentage Point Change in Assumed Health Care Cost Trend Rates) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($)
Pension Benefit Plan [Member]
Effect on Current Year Service and Interest Cost - Increase	$ 561
Effect on Projected Benefit Obligation - Increase	8,845
Other Benefits Plan [Member]
Effect on Current Year Service and Interest Cost - Decrease	(431)
Effect on Projected Benefit Obligation - Decrease	$ (6,941)

Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate.

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

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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.

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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.

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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.

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