Employee Benefit Plans - Pension Plan Asset Allocation (Details)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	100.00%
Percentage of Plan Assets at Year End	100.00%	100.00%
Weighted-Average Expected Long-Term Rate of Return	7.25%	7.25%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	55.00%
Percentage of Plan Assets at Year End	56.00%	54.00%
Weighted-Average Expected Long-Term Rate of Return	5.25%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	37.00%
Percentage of Plan Assets at Year End	37.00%	37.00%
Weighted-Average Expected Long-Term Rate of Return	1.97%
Money markets
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	8.00%
Percentage of Plan Assets at Year End	7.00%	9.00%
Weighted-Average Expected Long-Term Rate of Return	0.03%

This element represents the fair value of plan assets percentage.

No definition available.

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

Reference 2: 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=65897934&loc=d3e1928-114920

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

+ Details

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