Investments (Details-3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Equity method investment summarized assets [Abstract]
Total Current Assets	$ 238,197	$ 243,480
Total Assets	2,675,458	2,517,600	$ 2,371,906
Equity method investment summarized liabilities and equity [Abstract]
Total Current Liabilities	157,156	225,062
Total Other Credits	659,407	625,618
Total Liabilities and Capitalization	2,675,458	2,517,600
ATC [Member]
Equity method investment summarized income statement [Abstract]
Operating revenues	818,921	751,158	754,838
Operating expenses	(407,643)	(381,528)	(376,153)
Other income, net	2,452	1,171	1,144
Interest expense, net	(134,107)	(124,091)	(115,089)
Earnings before members' income taxes	279,623	246,710	$ 264,740
Equity method investment summarized assets [Abstract]
Total Current Assets	115,236	89,606
Total Noncurrent Assets	6,336,954	5,997,780
Total Assets	6,452,190	6,087,386
Equity method investment summarized liabilities and equity [Abstract]
Total Current Liabilities	495,919	511,945
Long-term debt	2,735,985	2,612,980
Total Other Credits	585,173	485,795
Total Equity	2,635,113	2,476,666
Total Liabilities and Capitalization	$ 6,452,190	$ 6,087,386