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Note 11 - Pension Plan and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Pension Plan [Member] |  |  |  |  |
Service Cost—Benefit Earned During the Period |  | $ 1,655 | $ 1,373 | $ 4,966 | $ 4,119
Interest Cost on Projected Benefit Obligation |  | 3,264 | 3,603 | 9,790 | 10,809
Expected Return on Assets |  | (5,506) | (5,324) | (16,516) | (15,973)
From Regulatory Asset |  | 0 | 1 | 0 | 4
From Other Comprehensive Income | [1] | 0 | 2 | 0 | 6
From Regulatory Asset |  | 2,231 | 1,163 | 6,693 | 3,488
From Other Comprehensive Income | [1] | 55 | 26 | 165 | 79
Net Periodic Pension Cost | [2] | 1,699 | 844 | 5,098 | 2,532
From Other Comprehensive Income | [1] | 55 | 26 | 165 | 79
Pension Plan [Member] | Costs Included in Electric Operation and Maintenance Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 1,099 | 1,007 | 3,476 | 2,961
Pension Plan [Member] | Costs Included in OTP Capital Expenditures [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 516 | 333 | 1,371 | 1,059
Pension Plan [Member] | Costs Included in Other Nonelectric Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 40 | 33 | 119 | 99
Pension Plan [Member] | Nonservice Costs Included in Nonservice Cost Components of Postretirement Benefits [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 31 | (401) | 96 | (1,179)
Pension Plan [Member] | Nonservice Costs Capitalized as Regulatory Assets [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 13 | (128) | 36 | (408)
Executive Survivor and Supplemental Retirement Plan [Member] |  |  |  |  |
Service Cost—Benefit Earned During the Period |  | 45 | 104 | 134 | 313
Interest Cost on Projected Benefit Obligation |  | 362 | 433 | 1,086 | 1,301
From Regulatory Asset |  | 0 | 2 | 0 | 4
From Other Comprehensive Income | [1] | 0 | 4 | 0 | 12
From Regulatory Asset |  | 24 | 31 | 71 | 93
From Other Comprehensive Income | [1] | 85 | 87 | 256 | 262
Net Periodic Pension Cost | [3] | 516 | 661 | 1,547 | 1,985
From Other Comprehensive Income | [1] | 85 | 87 | 256 | 262
Executive Survivor and Supplemental Retirement Plan [Member] | Costs Included in Electric Operation and Maintenance Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 0 | 26 | 0 | 78
Executive Survivor and Supplemental Retirement Plan [Member] | Costs Included in Other Nonelectric Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 45 | 78 | 134 | 235
Executive Survivor and Supplemental Retirement Plan [Member] | Nonservice Costs Included in Nonservice Cost Components of Postretirement Benefits [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 471 | 557 | 1,413 | 1,672
Other Postretirement Benefits Plan [Member] |  |  |  |  |
Service Cost—Benefit Earned During the Period |  | 461 | 321 | 1,385 | 964
Interest Cost on Projected Benefit Obligation |  | 598 | 770 | 1,795 | 2,312
From Regulatory Asset |  | (1,169) | 0 | (3,508) | 0
From Other Comprehensive Income | [1] | (28) | 0 | (86) | 0
From Regulatory Asset |  | 1,051 | 393 | 3,154 | 1,178
From Other Comprehensive Income | [1] | 26 | 10 | 78 | 29
Net Periodic Pension Cost | [4] | 939 | 1,494 | 2,818 | 4,483
From Other Comprehensive Income | [1] | 26 | 10 | 78 | 29
Effect of Medicare Part D Subsidy |  | 281 | (45) | 842 | (134)
Other Postretirement Benefits Plan [Member] | Costs Included in Electric Operation and Maintenance Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 306 | 235 | 970 | 693
Other Postretirement Benefits Plan [Member] | Costs Included in OTP Capital Expenditures [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 144 | 78 | 382 | 248
Other Postretirement Benefits Plan [Member] | Costs Included in Other Nonelectric Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 11 | 8 | 33 | 23
Other Postretirement Benefits Plan [Member] | Nonservice Costs Included in Nonservice Cost Components of Postretirement Benefits [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 328 | 889 | 1,037 | 2,614
Other Postretirement Benefits Plan [Member] | Nonservice Costs Capitalized as Regulatory Assets [Member] |  |  |  |  |
Net Periodic Pension Cost |  | $ 150 | $ 284 | $ 396 | $ 905
[1] | Corporate cost included in nonservice cost components of postretirement benefits.
[2] | Allocation of costs: Service costs included in OTP capital expenditures $ 516 $ 333 $ 1,371 $ 1,059 Service costs included in electric operation and maintenance expenses 1,099 1,007 3,476 2,961 Service costs included in other nonelectric expenses 40 33 119 99 Nonservice costs capitalized as regulatory assets 13 (128 ) 36 (408 ) Nonservice costs included in nonservice cost components of postretirement benefits 31 (401 ) 96 (1,179 )
[3] | Allocation of Costs: Service costs included in electric operation and maintenance expenses $ - $ 26 $ - $ 78 Service costs included in other nonelectric expenses 45 78 134 235 Nonservice costs included in nonservice cost components of postretirement benefits 471 557 1,413 1,672
[4] | Allocation of Costs: Service costs included in OTP capital expenditures $ 144 $ 78 $ 382 $ 248 Service costs included in electric operation and maintenance expenses 306 235 970 693 Service costs included in other nonelectric expenses 11 8 33 23 Nonservice costs capitalized as regulatory assets 150 284 396 905 Nonservice costs included in nonservice cost components of postretirement benefits 328 889 1,037 2,614

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- Definition The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation from other comprehensive income. + References No definition available. + Details
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