Retirement Benefit Plans (Percentage and Target Allocations) (Details)	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	100.00%	100.00%
Cash And Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	0.00%	1.00%
Cash And Equivalents [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	0.00%	0.00%
Cash And Equivalents [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	5.00%	5.00%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	49.00%	51.00%
Fixed Income Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	35.00%	35.00%
Fixed Income Securities [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	63.00%	63.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	43.00%	43.00%
Equity Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	35.00%	35.00%
Equity Securities [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	51.00%	51.00%
Real Assets Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan Assets	8.00%	5.00%
Real Assets Fund [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	0.00%	0.00%
Real Assets Fund [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	12.00%	12.00%

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- Definition

Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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