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Fair Value Measurements - Schedule of Costs and Fair Values of Investments in Debt Securities Held in Decommissioning Trust Fund (Details) - USD ($) $ in Thousands | Jun. 30, 2026 | Dec. 31, 2025
--- | --- | ---
Cost |  |
Less than 5 years | $ 35,616 | $ 23,565
5 years to 10 years | 0 | 0
Due after 10 years | 0 | 0
Total | 35,616 | 23,565
Estimated Fair Value |  |
Less than 5 years | 35,652 | 23,707
5 years to 10 years | 0 | 0
Due after 10 years | 0 | 0
Total | $ 35,652 | $ 23,707

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