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Property, Plant and Equipment (Tables) | 12 Months Ended
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Dec. 31, 2024
Property, Plant and Equipment [Abstract] |
Schedule of Property, Plant and Equipment | Major classes of property, plant and equipment as of December 31, 2024 and 2023 include:
(in thousands) | 2024 |  | 2023
Electric Plant in Service |  |  |
Production | $ | 1,469,008 |  |  | $ | 1,412,826 |
Transmission | 820,415 |  |  | 777,613 |
Distribution | 726,159 |  |  | 654,704 |
General | 165,361 |  |  | 144,738 |
Electric Plant in Service | 3,180,943 |  |  | 2,989,881 |
Construction Work in Progress | 231,890 |  |  | 137,212 |
Total Gross Electric Plant | 3,412,833 |  |  | 3,127,093 |
Less Accumulated Depreciation | 899,049 |  |  | 851,148 |
Net Electric Plant | 2,513,784 |  |  | 2,275,945 |
Nonelectric Property, Plant and Equipment |  |  |
Equipment | 260,307 |  |  | 233,571 |
Buildings and Leasehold Improvements | 88,680 |  |  | 64,753 |
Land | 13,578 |  |  | 13,600 |
Nonelectric Property, Plant and Equipment | 362,565 |  |  | 311,924 |
Construction Work in Progress | 40,536 |  |  | 38,062 |
Total Gross Nonelectric Property, Plant and Equipment | 403,101 |  |  | 349,986 |
Less Accumulated Depreciation | 224,425 |  |  | 207,556 |
Net Nonelectric Property, Plant and Equipment | 178,676 |  |  | 142,430 |
Net Property, Plant and Equipment | $ | 2,692,460 |  |  | $ | 2,418,375 |
Schedule of Jointly Owned Utility Plants | The following table provides OTP’s ownership percentages and amounts included in the December 31, 2024 and 2023 consolidated balance sheets for OTP’s share of each of these jointly owned facilities:
(dollars in thousands) | Ownership Percentage |  | Electric Plant in Service |  | Construction Work in Progress |  | Accumulated Depreciation |  | Net Plant
December 31, 2024 |  |  |  |  |  |  |  |  |
Big Stone Plant | 53.9 | % |  | $ | 345,990 |  |  | $ | 459 |  |  | $ | (135,065) |  |  | $ | 211,384 |
Coyote Station | 35.0 | % |  | 188,066 |  |  | 813 |  |  | (118,268) |  |  | 70,611 |
Big Stone South–Ellendale 345 kV line | 50.0 | % |  | 106,185 |  |  | — |  |  | (8,445) |  |  | 97,740 |
Fargo–Monticello 345 kV line | 14.2 | % |  | 78,184 |  |  | — |  |  | (12,247) |  |  | 65,937 |
Big Stone South–Brookings 345 kV line | 50.0 | % |  | 53,167 |  |  | — |  |  | (5,822) |  |  | 47,345 |
Brookings–Southeast Twin Cities 345 kV line | 4.8 | % |  | 28,013 |  |  | 1,131 |  |  | (3,941) |  |  | 25,203 |
Bemidji–Grand Rapids 230 kV line | 14.8 | % |  | 16,331 |  |  | — |  |  | (3,693) |  |  | 12,638 |
Jamestown– Ellendale 345 kV line | 50.0 | % |  | — |  |  | 5,509 |  |  | — |  |  | 5,509 |
Big Stone South–Alexandria 345 kV line | 40.0 | % |  | — |  |  | 2,418 |  |  | — |  |  | 2,418 |
Alexandria–Big Oaks 345 kV line | 14.2 | % |  | — |  |  | 417 |  |  | — |  |  | 417 |
Oslo - Lake Ardoch 115 kV line | 72.0 | % |  | — |  |  | 2,646 |  |  | — |  |  | 2,646 |
December 31, 2023 |  |  |  |  |  |  |  |  |
Big Stone Plant | 53.9 | % |  | $ | 341,683 |  |  | $ | 820 |  |  | $ | (126,904) |  |  | $ | 215,599 |
Coyote Station | 35.0 | % |  | 188,656 |  |  | 104 |  |  | (115,306) |  |  | 73,454 |
Big Stone South–Ellendale 345 kV line | 50.0 | % |  | 106,185 |  |  | — |  |  | (7,181) |  |  | 99,004 |
Fargo–Monticello 345 kV line | 14.2 | % |  | 78,184 |  |  | — |  |  | (11,238) |  |  | 66,946 |
Big Stone South–Brookings 345 kV line | 50.0 | % |  | 53,170 |  |  | — |  |  | (5,207) |  |  | 47,963 |
Brookings–Southeast Twin Cities 345 kV line | 4.8 | % |  | 26,409 |  |  | 83 |  |  | (3,617) |  |  | 22,875 |
Bemidji–Grand Rapids 230 kV line | 14.8 | % |  | 16,331 |  |  | — |  |  | (3,568) |  |  | 12,763 |
Jamestown–Ellendale 345 kV line | 50.0 | % |  | — |  |  | 1,121 |  |  | — |  |  | 1,121 |
Big Stone South–Alexandria 345 kV line | 40.0 | % |  | — |  |  | 555 |  |  | — |  |  | 555 |
Alexandria–Big Oaks 345 kV line | 14.2 | % |  | — |  |  | 343 |  |  | — |  |  | 343 |

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- Definition Tabular disclosure of physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation and depletion expense and method used, including composite depreciation, and accumulated deprecation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 360 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482099/360-10-50-1 + Details
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- Definition Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 360 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479070/980-360-S99-1 + Details
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