REVENUES: Electric utility operating revenues (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Revenues [Abstract]
Revenue from contracts with customers	$ 411,142	$ 417,897
Alternative revenue programs and other revenues	20,810	30,402
Electric utility revenues	$ 431,952	$ 448,299

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details