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Electric utility segment - Unconsolidated Variable Interest Entities (Details) $ in Millions | Sep. 30, 2025 USD ($) entity agreement | Mar. 31, 2025
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Power purchase agreement |  |
Number of IPPs (in entities) | entity | 2 |
GLST1, LLC |  |
Power purchase agreement |  |
Membership interest |  | 60.00%
Investment in unconsolidated affiliate | $ | $ 287.3 |
Hawaiian Electric Company |  |
Power purchase agreement |  |
Number of power purchase agreements (PPAs) (in agreements) | agreement | 4 |

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