Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 155	$ 214	$ 212
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	454	409	382
Deferred income taxes	(23)	6	(17)
Allowance for equity funds used during construction	(16)	(10)	(11)
Pension and other postretirement benefits	22	21	30
Decoupling mechanism deferrals, net of amortization	6	(2)	(2)
(Amortization) Deferral of net benefits due to Tax Reform	(23)	(23)	45
Share-based Payment Arrangement, Noncash Expense	11	9	5
Other non-cash income and expenses, net	22	34	16
Changes in working capital:
Decrease (increase) in receivables and unbilled revenues	(24)	30	(29)
(Increase) in margin deposits	8	0	(5)
(Decrease) increase in payables and accrued liabilities	26	(16)	51
Other working capital items, net	17	(12)	(11)
Contribution to non-qualified employee benefit trust	(11)	(11)	(11)
Contribution to pension and other postretirement plans	(2)	(65)	(12)
Asset Retirement Obligation, Cash Paid to Settle	(18)	(9)	(5)
Other, net	(37)	(29)	(8)
Net cash provided by operating activities	567	546	630
Cash flows from investing activities:
Capital expenditures	(784)	(606)	(595)
Purchases of nuclear decommissioning trust securities	(6)	(8)	(12)
Sales of nuclear decommissioning trust securities	9	13	15
Proceeds from Carty Settlement	0	0	120
Other, net	(6)	(3)	1
Net cash used in investing activities	(787)	(604)	(471)
Cash flows from financing activities:
Proceeds from issuance of long-term debt	549	470	75
Payments on long-term debt	(98)	(350)	(24)
Debt extinguishment costs	(2)	(9)	0
Proceeds from Short-term Debt	275	0	0
Repayments of Short-term Debt	(125)	0	0
Dividends paid	(140)	(134)	(125)
Other	(12)	(8)	(5)
Net cash used in financing activities	447	(31)	(79)
(Decrease) increase in cash and cash equivalents	227	(89)	80
Cash and cash equivalents, beginning of year	30	119	39
Cash and cash equivalents, end of year	257	30	119
Supplemental disclosures of cash flow information:
Cash paid for interest, net of amounts capitalized	113	116	117
Cash paid for income taxes	17	33	25
Non-cash investing and financing activities:
Accrued capital additions	72	76	61
Accrued dividends payable	38	36	34
Assets obtained under leasing arrangements	$ 0	$ 210	$ 24