CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net income	$ 107	$ 79	$ 98
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	158	139	128
Deferred income taxes	(36)	5	23
Allowance for equity funds used during construction	(5)	(3)	(9)
Provision for bad debts	7	7	4
Changes in operating assets and liabilities:
Accounts receivable	(12)	(10)	(5)
Accrued unbilled revenues	0	3	4
Inventories	(5)	(8)	(8)
Other current assets	(3)	13	2
Accounts payable	(3)	(10)	(9)
Net regulatory assets and liabilities	0	15	(20)
Other current liabilities	4	11	(13)
Pension and other employee benefit obligations	(7)	(7)	(15)
Other, net	(3)	0	3
Net cash provided by operating activities	202	234	183
Investing activities
Capital/construction expenditures	(238)	(212)	(226)
Net cash used in investing activities	(238)	(212)	(226)
Financing activities
(Repayments of) proceeds from short-term borrowings, net	(46)	13	40
Proceeds from issuance of long-term debt	97	0	197
Repayments of long-term debt	0	0	(151)
Capital contributions from parent	56	48	49
Dividends paid to parent	(70)	(84)	(91)
Net cash provided by (used in) financing activities	37	(23)	44
Net change in cash, cash equivalents and restricted cash	1	(1)	1
Cash, cash equivalents and restricted cash at beginning of period	1	2	1
Cash, cash equivalents and restricted cash at end of period	2	1	2
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(36)	(36)	(33)
Cash paid for income taxes, net	(26)	0	(21)
Other Noncash Investing and Financing Items [Abstract]
Supplemental disclosure of non-cash investing and financing transactions:	21	29	32
Inventory transfers to plant, property and equipment	5	9	8
Allowance for Funds Used During Construction, Investing Activities	$ 5	$ 3	$ 9