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Pension Benefits Fair Value of Plan Assets in Heirarchy (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 100.00% |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 100.00% | 100.00% |
Defined Benefit Plan, Plan Assets, Amount | $ 32,894,000 | $ 35,634,000 | $ 30,100,000
Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 23,676,000 | 26,672,000 |
Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 3,482,000 | 3,214,000 |
Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5,736,000 | 5,748,000 | 5,507,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 | 0 |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Realized Gain on Assets | 526,000 | 190,000 |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Unrealized Gain on Assets | 41,000 | 51,000 |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Disposition | $ (579,000) | $ 0 |
Defined Benefit Plan, Equity Securities, US |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 18.70% | 17.30% |
Defined Benefit Plan, Plan Assets, Amount | $ 6,149,000 | $ 6,176,000 |
Defined Benefit Plan, Equity Securities, US | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 4,165,000 | 4,130,000 |
Defined Benefit Plan, Equity Securities, US | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 1,984,000 | 2,046,000 |
Defined Benefit Plan, Equity Securities, US | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 |
Defined Benefit Plan, Equity Securities, Non-US |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 18.30% | 19.60% |
Defined Benefit Plan, Plan Assets, Amount | $ 6,010,000 | $ 6,958,000 |
Defined Benefit Plan, Equity Securities, Non-US | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 6,010,000 | 6,958,000 |
Defined Benefit Plan, Equity Securities, Non-US | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Defined Benefit Plan, Equity Securities, Non-US | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 |
Defined Benefit Plan, Equity Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 36.00% |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 37.00% | 36.90% |
Defined Benefit Plan, Plan Assets, Amount | $ 12,159,000 | $ 13,134,000 |
Defined Benefit Plan, Equity Securities | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 10,175,000 | 11,088,000 |
Defined Benefit Plan, Equity Securities | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 1,984,000 | 2,046,000 |
Defined Benefit Plan, Equity Securities | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 |
Core fixed income [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 16.60% | 31.40% |
Defined Benefit Plan, Plan Assets, Amount | $ 5,447,000 | $ 11,199,000 |
Core fixed income [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5,447,000 | 11,199,000 |
Core fixed income [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Core fixed income [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 |
Corporate Debt Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 8.30% | 6.70% |
Defined Benefit Plan, Plan Assets, Amount | $ 2,755,000 | $ 2,379,000 |
Corporate Debt Securities | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 2,755,000 | 2,379,000 |
Corporate Debt Securities | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Corporate Debt Securities | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 |
Total fixed income securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 37.00% |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 24.90% | 38.10% |
Defined Benefit Plan, Plan Assets, Amount | $ 8,202,000 | $ 13,578,000 |
Total fixed income securities [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 8,202,000 | 13,578,000 |
Total fixed income securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Total fixed income securities [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 |
Defined Benefit Plan, Real Estate |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 5.70% | 5.40% |
Defined Benefit Plan, Plan Assets, Amount | $ 1,870,000 | $ 1,929,000 |
Defined Benefit Plan, Real Estate | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Defined Benefit Plan, Real Estate | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Defined Benefit Plan, Real Estate | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 1,870,000 | $ 1,929,000 |
Defined Benefit Plan, Common Collective Trust |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 4.60% | 3.30% |
Defined Benefit Plan, Plan Assets, Amount | $ 1,498,000 | $ 1,168,000 |
Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 1,498,000 | 1,168,000 |
Defined Benefit Plan, Common Collective Trust | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 |
Hedge fund [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 27.80% | 16.30% |
Defined Benefit Plan, Plan Assets, Amount | $ 9,165,000 | $ 5,825,000 |
Hedge fund [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5,299,000 | 2,006,000 |
Hedge fund [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Hedge fund [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 3,866,000 | $ 3,819,000 |
Total other securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage | 27.00% |  |
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage | 38.10% | 25.00% |
Defined Benefit Plan, Plan Assets, Amount | $ 12,533,000 | $ 8,922,000 |
Total other securities [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5,299,000 | 2,006,000 |
Total other securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 1,498,000 | 1,168,000 |
Total other securities [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 5,736,000 | 5,748,000 |
Nonqualified Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 | $ 0

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