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Retirement Benefit Plans (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Dec. 31, 2018
Net Periodic Benefit Cost [Line Items] |  |  |  |  |
Employer matching contribution, percentage |  |  | 5.00% |  |
Employees' Pension Plan |  |  |  |  |
Net Periodic Benefit Cost [Line Items] |  |  |  |  |
Assumptions used calculating benefit obligation, interest rate to annuitize cash balance account |  |  |  |  | 3.43%
Service Cost | $ 382 | $ 389 | $ 1,146 | $ 1,168 |
Interest Cost | 513 | 400 | 1,253 | 1,199 |
Expected Return on Plan Assets | (765) | (841) | (2,296) | (2,522) |
Amortization of Prior Service (Credit) Cost | 17 | (12) | 52 | (37) |
Amortization of Net Loss | 153 | 48 | 460 | 145 |
Net Periodic Cost | 300 | (16) | 615 | (47) |
Plan Contributions During the Period | 0 | 0 | 0 | 0 |
Estimated Future Contributions in the Current Fiscal Year | 0 |  | 0 |  |
Select Executive Retirement Plan |  |  |  |  |
Net Periodic Benefit Cost [Line Items] |  |  |  |  |
Assumptions used calculating benefit obligation, interest rate to annuitize cash balance account |  |  |  |  | 4.46%
Service Cost | 81 | 104 | 243 | 311 |
Interest Cost | 54 | 48 | 162 | 152 |
Expected Return on Plan Assets | 0 | 0 | 0 | 0 |
Amortization of Prior Service (Credit) Cost | 14 | 14 | 41 | 43 |
Amortization of Net Loss | 29 | 33 | 86 | 99 |
Net Periodic Cost | 178 | 199 | 532 | 605 |
Plan Contributions During the Period | 117 | 116 | 350 | 349 |
Estimated Future Contributions in the Current Fiscal Year | 0 |  | 0 |  |
Post-Retirement Benefit Plans |  |  |  |  |
Net Periodic Benefit Cost [Line Items] |  |  |  |  |
Assumptions used calculating benefit obligation, interest rate to annuitize cash balance account |  |  |  |  | 4.88%
Service Cost | 30 | 34 | 91 | 102 |
Interest Cost | 91 | 81 | 273 | 248 |
Expected Return on Plan Assets | 0 | 0 | 0 | 0 |
Amortization of Prior Service (Credit) Cost | 25 | 25 | 76 | 75 |
Amortization of Net Loss | (10) | 0 | (32) | 0 |
Net Periodic Cost | 136 | 140 | 408 | 425 |
Plan Contributions During the Period | 51 | $ 56 | 142 | $ 175 |
Estimated Future Contributions in the Current Fiscal Year | $ 0 |  | $ 0 |  |
On or Subsequent to January 1, 2003 |  |  |  |  |
Net Periodic Benefit Cost [Line Items] |  |  |  |  |
Service credits, percent of eligible salaries |  |  | 6.00% |  |
Minimum | Prior to January 1, 2003 |  |  |  |  |
Net Periodic Benefit Cost [Line Items] |  |  |  |  |
Service credits, percent of eligible salaries |  |  | 6.00% |  |
Maximum | Prior to January 1, 2003 |  |  |  |  |
Net Periodic Benefit Cost [Line Items] |  |  |  |  |
Service credits, percent of eligible salaries |  |  | 12.00% |  |

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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: 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 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
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