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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 | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Pension Plan [Member] |  |  |  |  |
Service Cost—Benefit Earned During the Period |  | $ 1,656 | $ 1,373 | $ 3,311 | $ 2,746
Interest Cost on Projected Benefit Obligation |  | 3,263 | 3,603 | 6,526 | 7,206
Expected Return on Assets |  | (5,505) | (5,324) | (11,010) | (10,649)
From Regulatory Asset |  | 0 | 2 | 0 | 3
From Other Comprehensive Income | [1] | 0 | 2 | 0 | 4
From Regulatory Asset |  | 2,231 | 1,162 | 4,462 | 2,325
From Other Comprehensive Income | [1] | 55 | 26 | 110 | 53
Net Periodic Pension Cost | [2] | 1,700 | 844 | 3,399 | 1,688
From Other Comprehensive Income | [1] | 55 | 26 | 110 | 53
From Regulatory Asset |  | (2,231) | (1,162) | (4,462) | (2,325)
Pension Plan [Member] | Costs Included in Electric Operation and Maintenance Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 1,185 | 1,004 | 2,377 | 1,954
Pension Plan [Member] | Costs Included in OTP Capital Expenditures [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 432 | 336 | 855 | 726
Pension Plan [Member] | Costs Included in Other Nonelectric Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 39 | 33 | 79 | 66
Pension Plan [Member] | Nonservice Costs Included in Nonservice Cost Components of Postretirement Benefits [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 32 | (399) | 65 | (778)
Pension Plan [Member] | Nonservice Costs Capitalized as Regulatory Assets [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 12 | (130) | 23 | (280)
Executive Survivor and Supplemental Retirement Plan [Member] |  |  |  |  |
Service Cost—Benefit Earned During the Period |  | 44 | 104 | 89 | 209
Interest Cost on Projected Benefit Obligation |  | 362 | 434 | 724 | 868
From Regulatory Asset |  | 0 | 1 | 0 | 2
From Other Comprehensive Income | [3] | 0 | 4 | 0 | 8
From Regulatory Asset |  | 24 | 31 | 47 | 62
From Other Comprehensive Income | [3] | 85 | 88 | 171 | 175
Net Periodic Pension Cost | [4] | 515 | 662 | 1,031 | 1,324
From Other Comprehensive Income | [3] | 85 | 88 | 171 | 175
From Regulatory Asset |  | (24) | (31) | (47) | (62)
Executive Survivor and Supplemental Retirement Plan [Member] | Costs Included in Electric Operation and Maintenance Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 0 | 26 | 0 | 52
Executive Survivor and Supplemental Retirement Plan [Member] | Costs Included in Other Nonelectric Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 44 | 78 | 89 | 157
Executive Survivor and Supplemental Retirement Plan [Member] | Nonservice Costs Included in Nonservice Cost Components of Postretirement Benefits [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 471 | 558 | 942 | 1,115
Other Postretirement Benefits Plan [Member] |  |  |  |  |
Service Cost—Benefit Earned During the Period |  | 462 | 322 | 924 | 643
Interest Cost on Projected Benefit Obligation |  | 599 | 772 | 1,197 | 1,542
From Regulatory Asset |  | (1,170) | 0 | (2,339) | 0
From Other Comprehensive Income | [1] | (29) | 0 | (58) | 0
From Regulatory Asset |  | (1,052) | (392) | (2,103) | (785)
From Other Comprehensive Income | [1] | 26 | 9 | 52 | 19
Net Periodic Pension Cost | [5] | 940 | 1,495 | 1,879 | 2,989
From Other Comprehensive Income | [1] | 26 | 9 | 52 | 19
From Regulatory Asset |  | 1,052 | 392 | 2,103 | 785
Effect of Medicare Part D Subsidy |  | 280 | (44) | 561 | (89)
Other Postretirement Benefits Plan [Member] | Costs Included in Electric Operation and Maintenance Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 331 | 235 | 664 | 458
Other Postretirement Benefits Plan [Member] | Costs Included in OTP Capital Expenditures [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 120 | 79 | 238 | 170
Other Postretirement Benefits Plan [Member] | Costs Included in Other Nonelectric Expenses [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 11 | 8 | 22 | 15
Other Postretirement Benefits Plan [Member] | Nonservice Costs Included in Nonservice Cost Components of Postretirement Benefits [Member] |  |  |  |  |
Net Periodic Pension Cost |  | 354 | 885 | 709 | 1,725
Other Postretirement Benefits Plan [Member] | Nonservice Costs Capitalized as Regulatory Assets [Member] |  |  |  |  |
Net Periodic Pension Cost |  | $ 124 | $ 288 | $ 246 | $ 621
[1] | Corporate cost included in nonservice cost components of postretirement benefits.
[2] | Allocation of costs: Service costs included in OTP capital expenditures $ 432 $ 336 $ 855 $ 726 Service costs included in electric operation and maintenance expenses 1,185 1,004 2,377 1,954 Service costs included in other nonelectric expenses 39 33 79 66 Nonservice costs capitalized as regulatory assets 12 (130 ) 23 (280 ) Nonservice costs included in nonservice cost components of postretirement benefits 32 (399 ) 65 (778 )
[3] | Amortization of prior service costs and net actuarial losses from other comprehensive income are included in nonservice cost components of postretirement benefits.
[4] | Allocation of Costs: Service costs included in electric operation and maintenance expenses $ - $ 26 $ - $ 52 Service costs included in other nonelectric expenses 44 78 89 157 Nonservice costs included in nonservice cost components of postretirement benefits 471 558 942 1,115
[5] | Allocation of Costs: Service costs included in OTP capital expenditures $ 120 $ 79 $ 238 $ 170 Service costs included in electric operation and maintenance expenses 331 235 664 458 Service costs included in other nonelectric expenses 11 8 22 15 Nonservice costs capitalized as regulatory assets 124 288 246 621 Nonservice costs included in nonservice cost components of postretirement benefits 354 885 709 1,725

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