Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Weighted average rate of compensation increase used to determine net periodic benefit cost 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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Details

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Employee Retirement Benefits (Weighted-Average Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Benefit Obligations \| Pension Plan
Schedule of Benefit Obligations Weighted Average Assumptions
Discount rate	3.73%	4.30%
Benefit Obligations \| Pension Plan \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	2.75%	2.75%
Benefit Obligations \| Pension Plan \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	3.25%	3.25%
Benefit Obligations \| Supplemental Employee Retirement Plan
Schedule of Benefit Obligations Weighted Average Assumptions
Discount rate	3.61%	4.10%
Benefit Obligations \| Supplemental Employee Retirement Plan \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	2.75%	2.75%
Benefit Obligations \| Supplemental Employee Retirement Plan \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	3.25%	3.25%
Net Periodic Benefit Cost \| Pension Plan
Schedule of Benefit Obligations Weighted Average Assumptions
Discount rate	4.30%	4.55%	4.25%
Expected return on plan assets	7.25%	7.25%	7.25%
Net Periodic Benefit Cost \| Pension Plan \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	2.75%	2.75%	2.75%
Net Periodic Benefit Cost \| Pension Plan \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	3.25%	3.25%	3.25%
Net Periodic Benefit Cost \| Supplemental Employee Retirement Plan
Schedule of Benefit Obligations Weighted Average Assumptions
Discount rate	4.10%	4.30%	4.05%
Net Periodic Benefit Cost \| Supplemental Employee Retirement Plan \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	2.75%	2.75%	2.75%
Net Periodic Benefit Cost \| Supplemental Employee Retirement Plan \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	3.25%	3.25%	3.25%