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Fair Value Measurements - Schedule of Investments in Debt Securities Held by Decommissioning Trust Fund (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2026 | Jun. 30, 2025 | Jun. 30, 2026 | Jun. 30, 2025
Fair Value Measurements |  |  |  |
Purchases | $ 209 | $ 198 | $ 12,051 | $ 12,406
Net Proceeds | 149 | 25 | 182 | (579)
Unrealized Gain (Loss) | (18) | 22 | (106) | 131
Debt securities held in decommissioning trust fund |  |  |  |
Fair Value Measurements |  |  |  |
Purchases | 209 | 198 | 12,051 | 12,406
Net Proceeds | 0 | 0 | 0 | 0
Unrealized Gain (Loss) | (18) | 22 | (106) | 131
Cash and cash equivalents |  |  |  |
Fair Value Measurements |  |  |  |
Purchases | 0 | 0 | 0 | 0
Net Proceeds | (7) | 2 | 1 | (745)
Unrealized Gain (Loss) | 0 | 0 | 0 | 0
Other |  |  |  |
Fair Value Measurements |  |  |  |
Purchases | 0 | 0 | 0 | 0
Net Proceeds | 156 | 23 | 181 | 166
Unrealized Gain (Loss) | $ 0 | $ 0 | $ 0 | $ 0

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