Investment in ATC and ATC Holdco (Details-2) - ATC [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Schedule of Equity Method Investments [Line Items]
Operating revenues	$ 203,776	$ 191,605	$ 404,202	$ 382,604
Operating expenses	(101,517)	(95,256)	(200,593)	(190,747)
Other income, net	565	344	956	748
Interest expense, net	(33,504)	(29,059)	(66,414)	(57,499)
Earnings before members' income taxes	$ 69,320	$ 67,634	$ 138,151	$ 135,106