CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash Flows from Operating Activities:
Net income (loss)	$ (973)	$ 634
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	885	938
Depreciation and amortization on assets held for sale	0	49
Amortization of deferred financing costs	23	22
Amortization of intangible assets in non-utility cost of revenues	1	19
Deferred income taxes	(429)	8
Goodwill impairment and loss from reclassification to held for sale	175	0
Goodwill Impairment	185	0
Unrealized loss (gain) on marketable securities	(14)	(206)
Loss (gain) on indexed debt securities	25	216
Write-down of natural gas inventory	3	5
Equity in (earnings) losses of unconsolidated affiliates	1,499	(213)
Distributions from unconsolidated affiliates	109	226
Pension contributions	(84)	(94)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	326	521
Inventory	(50)	(85)
Taxes receivable	4	(69)
Accounts payable	(251)	(646)
Fuel cost recovery	(5)	68
Non-trading derivatives, net	(14)	(66)
Margin deposits, net	65	(33)
Interest and taxes accrued	(53)	(89)
Net regulatory assets and liabilities	(76)	(101)
Other current assets	6	31
Other current liabilities	30	(118)
Other assets	5	81
Other liabilities	46	(22)
Other operating activities, net	1	10
Net cash provided by operating activities from continuing operations	1,439	1,086
Cash Flows from Investing Activities:
Capital expenditures	(1,889)	(1,822)
Acquisitions, net of cash acquired	0	(5,991)
Distributions from unconsolidated affiliate in excess of cumulative earnings	46	0
Proceeds from divestitures (Note 3)	1,136	0
Other investing activities, net	24	38
Net cash used in investing activities from continuing operations	(683)	(7,775)
Cash Flows from Financing Activities:
Increase in short-term borrowings, net	37	0
Proceeds from (payments of) commercial paper, net	(1,057)	1,584
Proceeds from long-term debt, net	299	2,916
Payments of long-term debt	(1,060)	(1,225)
Payment of debt issuance costs	(4)	(19)
Payment of dividends on Common Stock	(309)	(433)
Payment of dividends on Preferred Stock	(114)	(101)
Proceeds from issuance of Common Stock, net	672	0
Proceeds from issuance of Series C Preferred Stock, net	723	0
Other financing activities, net	(6)	(14)
Net cash provided by (used in) financing activities from continuing operations	(819)	2,708
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(63)	(3,981)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	271	4,278
Cash, Cash Equivalents and Restricted Cash at End of Period	208	297
Houston Electric [Member]
Cash Flows from Operating Activities:
Net income (loss)	277	312
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	420	519
Amortization of deferred financing costs	8	8
Deferred income taxes	(36)	(39)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	(145)	(84)
Accounts receivable/payable–affiliated companies	10	(7)
Inventory	(35)	(9)
Taxes receivable	0	5
Accounts payable	(7)	3
Non-trading derivatives, net	15	(25)
Interest and taxes accrued	16	(28)
Net regulatory assets and liabilities	5	(58)
Other current assets	13	15
Other current liabilities	21	(3)
Other assets	(5)	8
Other liabilities	6	(13)
Other operating activities, net	(11)	(9)
Net cash provided by operating activities from continuing operations	552	595
Cash Flows from Investing Activities:
Capital expenditures	(750)	(744)
Decrease (increase) in notes receivable–affiliated companies	456	(772)
Other investing activities, net	11	12
Net cash used in investing activities from continuing operations	(283)	(1,504)
Cash Flows from Financing Activities:
Increase in short-term borrowings, net	5	0
Proceeds from long-term debt, net	299	696
Payments of long-term debt	(160)	(390)
Decrease in notes payable–affiliated companies	0	(1)
Dividend to parent	(457)	(100)
Contribution from parent	0	590
Capital distribution to parent associated with the sale of CES	0	0
Payment of debt issuance costs	(3)	(8)
Other financing activities, net	0	(1)
Net cash provided by (used in) financing activities from continuing operations	(316)	786
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(47)	(123)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	235	370
Cash, Cash Equivalents and Restricted Cash at End of Period	188	247
CERC Corp [Member]
Cash Flows from Operating Activities:
Net income (loss)	76	159
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	226	218
Depreciation and amortization on assets held for sale	0	10
Amortization of deferred financing costs	7	8
Deferred income taxes	19	26
Goodwill impairment and loss from reclassification to held for sale	93	0
Write-down of natural gas inventory	3	5
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	402	653
Accounts receivable/payable–affiliated companies	(8)	(9)
Inventory	(3)	(47)
Taxes receivable	0	4
Accounts payable	(180)	(458)
Fuel cost recovery	(5)	68
Non-trading derivatives, net	(13)	(60)
Margin deposits, net	65	(33)
Interest and taxes accrued	(18)	(23)
Net regulatory assets and liabilities	(23)	(1)
Other current assets	4	11
Other current liabilities	(7)	(9)
Other assets	7	(3)
Other liabilities	8	2
Other operating activities, net	(7)	0
Net cash provided by operating activities from continuing operations	646	513
Cash Flows from Investing Activities:
Capital expenditures	(624)	(546)
Decrease (increase) in notes receivable–affiliated companies	(9)	27
Proceeds from divestitures (Note 3)	286	0
Other investing activities, net	8	4
Net cash used in investing activities from continuing operations	(339)	(515)
Cash Flows from Financing Activities:
Increase in short-term borrowings, net	31	0
Proceeds from (payments of) commercial paper, net	30	100
Dividend to parent	(80)	(119)
Contribution from parent	0	0
Capital distribution to parent associated with the sale of CES	(286)	0
Other financing activities, net	(2)	(2)
Net cash provided by (used in) financing activities from continuing operations	(307)	(21)
Net Decrease in Cash, Cash Equivalents and Restricted Cash	0	(23)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	2	25
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 2	$ 2