Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
OPERATING ACTIVITIES:
Net income	$ 94,974	$ 101,574
Adjustments to reconcile net cash provided (used) by operating activities:
Depreciation and amortization	85,659	84,666
Regulatory debits	1,184	1,067
Regulatory charges resulting from tax rate changes	17,637	17,637
Amortization of deferred charges and credits	(3,638)	(2,784)
Allowance for equity funds used during construction (equity AFUDC)	(1,853)	(960)
Changes in current assets and liabilities:
Trade and other accounts receivable	3,911	4,769
Affiliate receivables	109	(119)
Materials and supplies	58	129
Other current assets	(449)	(5,253)
Trade accounts payable	(890)	(774)
Affiliate payables	(2,513)	11,735
Regulatory liabilities	137,451	0
Other accrued liabilities	6,675	13,109
Changes in long-term assets and liabilities:
Regulatory liabilities	(133,578)	3,179
Other, net	1,674	(2,489)
Net cash provided (used) by operating activities	206,411	225,486
FINANCING ACTIVITIES:
Cash distributions to parent	(108,000)	(133,000)
Net cash provided (used) by financing activities	(108,000)	(133,000)
Property, plant and equipment:
Capital expenditures	(60,637)	(51,233)
Contributions and advances for construction costs	10,042	7,146
Disposal of property, plant and equipment, net	(4,462)	(3,638)
Advances to affiliate, net	(43,354)	(44,761)
Net cash provided (used) by investing activities	(98,411)	(92,486)
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	(73,267)	(58,566)
Changes in related accounts payable and accrued liabilities	12,630	7,333
Capital expenditures	$ (60,637)	$ (51,233)