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Components of Net Periodic Benefit Cost (Details Textual) - USD ($) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2017 | Jun. 30, 2016 | Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefits Plan Estimated Future Employer Contributions In Next Fiscal Year |  |  | $ 2,500
Defined Benefit Plan, Expected Future Benefit Payment, Remainder of Fiscal Year |  |  | 858
Defined Contribution Plan Employer Accrued Discretionary Contribution Amount | $ 867 | $ 826 |
Post Retirement Health Benefits [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefits Plan Estimated Future Employer Contributions In Next Fiscal Year |  |  | $ 260
Defined Benefit Plan, Plan Assets, Contributions by Employer | 111 |  |
Pension Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Contributions by Employer | $ 977 |  |

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- Definition Amount of potential discretionary contributions accrued to a defined contribution plan. + References No definition available. + Details
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- Definition Amount of contribution received by defined benefit plan from employer which increases plan assets. + 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 (d)(5)(ii) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2709-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(5)(iv)(01) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year. + 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 (f) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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