CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net income	$ 128	$ 107
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	223	204
Nuclear fuel amortization	30	33
Deferred income taxes	(8)	(15)
Allowance for equity funds used during construction	(7)	(7)
Provision for bad debts	6	5
Net realized and unrealized hedging and derivatives transactions	(6)	9
Changes in operating assets and liabilities:
Accounts receivable	(12)	3
Accrued unbilled revenues	43	52
Inventories	38	20
Accounts payable	(38)	(43)
Net regulatory assets and liabilities	(268)	33
Other current liabilities	26	(4)
Pension and other employee benefit obligations	(36)	(48)
Other, net	(2)	(8)
Net cash provided by operating activities	117	341
Investing activities
Capital/construction expenditures	(474)	(274)
Purchase of investment securities	(199)	(835)
Proceeds from the sale of investment securities	194	830
Investments in utility money pool arrangement	0	(305)
Repayments from utility money pool arrangement	0	257
Other, net	(2)	1
Net cash used in investing activities	(481)	(326)
Financing activities
Repayments of short-term borrowings, net	(179)	(30)
Borrowings under utility money pool arrangement	434	118
Repayments under utility money pool arrangement	(434)	(118)
Proceeds from issuance of long-term debt	836	0
Capital contributions from parent	424	114
Dividends paid to parent	(106)	(94)
Other, net	0	(4)
Net cash provided by (used in) financing activities	975	(14)
Net change in cash, cash equivalents and restricted cash	611	1
Cash, cash equivalents and restricted cash at beginning of period	46	126
Cash, cash equivalents and restricted cash at end of period	657	127
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(72)	(75)
Cash received (paid) for income taxes, net	1	(6)
Other Noncash Investing and Financing Items [Abstract]
Accrued property, plant and equipment additions	222	67
Inventory transfers to property, plant and equipment	5	4
Allowance for equity funds used during construction	$ 7	$ 7