Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
OPERATING ACTIVITIES:
Net income	$ 53,095	$ 49,038
Adjustments to reconcile net cash provided (used) by operating activities:
Depreciation and amortization	27,465	27,877
Allowance for equity funds used during construction (equity AFUDC)	(1,334)	(693)
Changes in current assets and liabilities:
Trade and other accounts receivable	963	2,497
Affiliate receivables	587	(24)
Materials and supplies	(42)	(16)
Regulatory assets	(54)	(71)
Other current assets	(552)	1,188
Trade accounts payable	(5,429)	(358)
Affiliate payables	(2,915)	(1,319)
Regulatory liabilities	(3)	(125,506)
Other accrued liabilities	15,262	5,622
Other, including changes in long-term assets and liabilities:
Other, net	(6,570)	(10,575)
Net cash provided (used) by operating activities	80,473	(52,340)
FINANCING ACTIVITIES:
Cash distributions to parent	(33,000)	(35,800)
Net cash provided (used) by financing activities	(33,000)	(35,800)
Property, plant and equipment:
Capital expenditures	(40,391)	(22,038)
Contributions and advances for construction costs	2,995	1,657
Disposal of property, plant and equipment, net	1,197	(411)
Advances to affiliate, net	(11,274)	108,932
Net cash provided (used) by investing activities	(47,473)	88,140
Increase (decrease) in cash	0	0
Cash at beginning of period	0	0
Cash at end of period	0	0
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Increases to property, plant and equipment, exclusive of equity AFUDC	(37,111)	(10,613)
Changes in related accounts payable and accrued liabilities	(3,280)	(11,425)
Capital expenditures	$ (40,391)	$ (22,038)