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SEGMENTS OF BUSINESS - Summary of reportable segments operations (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023 | Dec. 31, 2023
Segment Reporting Information [Line Items] |  |  |  |  |  |
Operating revenues |  | $ 105,044 | $ 165,768 | $ 310,175 | $ 515,296 |
Operating Expense |  | 100,332 | 141,965 | 310,016 | 440,016 |
Income (loss) from operations |  | 4,712 | 23,803 | 159 | 75,280 |
Depreciation, Depletion and Amortization |  | 13,838 | 16,230 | 42,930 | 51,375 |
Assets |  | 579,730 | 585,186 | 579,730 | 585,186 | $ 589,780
Capital Expenditures |  | 11,562 | 18,136 | 39,606 | 48,746 |
Other revenues |  | 1,667 | 945 | 4,221 | 3,888 |
Electric Operations |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Operating revenues | [1] | 71,902 | 67,544 | 192,379 | 231,141 |
Operating Expense |  | 52,547 | 70,220 | 150,989 | 205,856 |
Income (loss) from operations |  | 19,355 | (2,676) | 41,390 | 25,285 |
Depreciation, Depletion and Amortization |  | 4,802 | 4,695 | 14,197 | 14,045 |
Assets |  | 217,826 | 209,455 | 217,826 | 209,455 |
Capital Expenditures |  | 4,602 | 6,566 | 16,121 | 10,092 |
Amortization of contract liability |  | 11,306 | 10,281 | 36,174 | 63,183 |
Electric Operations | Capacity revenue |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Operating revenues |  | 15,860 | 13,012 | 44,506 | 46,137 |
Electric Operations | Delivered energy |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Other revenues |  | 44,549 | 44,110 | 111,181 | 121,492 |
Electric Operations | Other operating revenue |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Other revenues |  | 187 | 141 | 518 | 329 |
Coal Operations |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Operating revenues |  | 49,331 | 134,896 | 162,630 | 343,267 |
Operating Expense |  | 61,510 | 110,132 | 197,587 | 279,052 |
Income (loss) from operations |  | (12,179) | 24,764 | (34,957) | 64,215 |
Depreciation, Depletion and Amortization |  | 9,013 | 11,508 | 28,671 | 37,249 |
Assets |  | 356,252 | 375,682 | 356,252 | 375,682 |
Capital Expenditures |  | 6,810 | 11,570 | 23,002 | 38,654 |
Corporate and other and eliminations |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Operating revenues |  | (16,189) | (36,672) | (44,834) | (59,112) |
Operating Expense |  | (13,725) | (38,387) | (38,560) | (44,892) |
Income (loss) from operations |  | (2,464) | 1,715 | (6,274) | (14,220) |
Depreciation, Depletion and Amortization |  | 23 | 27 | 62 | 81 |
Assets |  | 5,652 | 49 | 5,652 | 49 |
Capital Expenditures |  | $ 150 | $ 0 | $ 483 | $ 0 |
[1] | Electric operations revenue as of each period presented were comprised of the components noted below (in thousands):

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