Electric utility segment - Consolidated Variable Interest Entities (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Variable Interest Entity [Line Items]
Accounts receivable and unbilled revenues, net	$ 452,184	$ 491,526
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Accounts receivable and unbilled revenues, net	$ 317,000