CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net income	$ 1,372	$ 1,261	$ 1,148
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	1,785	1,659	1,495
Nuclear fuel amortization	119	122	114
Deferred income taxes	143	218	640
Allowance for equity funds used during construction	(77)	(108)	(75)
Equity earnings of unconsolidated subsidiaries	(39)	(35)	(30)
Dividends from unconsolidated subsidiaries	40	37	41
Provision for bad debts	42	42	39
Share-based compensation expense	58	45	57
Net realized and unrealized hedging and derivative transactions	45	22	2
Changes in operating assets and liabilities:
Accounts receivable	(20)	(105)	(60)
Accrued unbilled revenues	42	9	(34)
Inventories	(84)	(65)	(3)
Other current assets	25	18	9
Accounts payable	(12)	90	43
Net regulatory assets and liabilities	(66)	223	(16)
Other current liabilities	(15)	(61)	(38)
Pension and other employee benefit obligations	(135)	(179)	(133)
Other, net	40	(71)	(73)
Net cash provided by operating activities	3,263	3,122	3,126
Investing activities
Utility capital/construction expenditures	(4,225)	(3,957)	(3,244)
Purchases of investment securities	(995)	(853)	(1,697)
Proceeds from the sale of investment securities	975	833	1,669
Other, net	(98)	(9)	(24)
Net cash used in investing activities	(4,343)	(3,986)	(3,296)
Financing activities
(Repayments of) proceeds from short-term borrowings, net	(443)	225	422
Proceeds from issuance of long-term debt	2,920	1,675	1,518
Repayments of long-term debt, including reacquisition premiums	(949)	(452)	(1,030)
Proceeds from issuance of common stock	458	230	0
Dividends paid	(791)	(730)	(721)
Other, net	(14)	(20)	(21)
Net cash provided by financing activities	1,181	928	168
Net change in cash and cash equivalents	101	64	(2)
Cash and cash equivalents at beginning of period	147	83	85
Cash and cash equivalents at end of period	248	147	83
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(698)	(633)	(616)
Cash received for income taxes, net	53	27	44
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	421	388	464
Inventory transfers to plant, property and equipment	88	129	63
Operating lease right-of-use assets	1,843	0	0
Allowance for equity funds used during construction	77	108	75
Issuance of common stock for reinvested dividends and equity awards	$ 63	$ 67	$ 31