Retirement Benefits (Future Postretirement Health Care and Life Insurance Benefit Payments) (Details) - Postretirement Health Care And Life Insurance Benefit Plans [Member] $ in Thousands	Dec. 31, 2019 USD ($)
Pension Postretirement And Other Retirement Plans [Line Items]
Before Medicare Subsidy 2020	$ 1,945
Before Medicare Subsidy 2021	1,846
Before Medicare Subsidy 2022	1,741
Before Medicare Subsidy 2023	1,635
Before Medicare Subsidy 2024	1,537
Before Medicare Subsidy 2025-2029	6,181
After Medicare Subsidy, 2020	1,737
After Medicare Subsidy, 2021	1,651
After Medicare Subsidy, 2022	1,559
After Medicare Subsidy, 2023	1,466
After Medicare Subsidy, 2024	1,382
After Medicare Subsidy, 2025-2029	$ 5,589

Defined Benefit Plan Expected Future Benefit Payments After Medicare Subsidy Five Fiscal Years Thereafter

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- Definition

Defined Benefit Plan Expected Future Benefit Payments After Medicare Subsidy Next Twelve Months

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- Definition

Defined Benefit Plan Expected Future Benefit Payments After Medicare Subsidy Year Five

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- Definition

Defined Benefit Plan Expected Future Benefit Payments After Medicare Subsidy Year Four

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- Definition

Defined Benefit Plan Expected Future Benefit Payments After Medicare Subsidy Year Three

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- Definition

Defined Benefit Plan Expected Future Benefit Payments After Medicare Subsidy Year Two

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- Definition

Pension Postretirement And Other Retirement Plans [Line Items]

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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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- Definition

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

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- Definition

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

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- Definition

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

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

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

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