CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash Flows from Operating Activities:
Net income (loss)	$ (1,199)	$ 169
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	282	300
Depreciation and amortization on assets held for sale	0	13
Amortization of deferred financing costs	7	7
Amortization of intangible assets in non-utility cost of revenues	1	9
Deferred income taxes	(377)	(14)
Goodwill impairment and loss from reclassification to held for sale	214	0
Goodwill Impairment	185	0
Unrealized loss (gain) on marketable securities	144	(83)
Loss (gain) on indexed debt securities	(135)	86
Write-down of natural gas inventory	3	1
Equity in (earnings) losses of unconsolidated affiliates	1,475	(62)
Distributions from unconsolidated affiliates	70	74
Pension contributions	(2)	(2)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	236	138
Inventory	110	120
Taxes receivable	13	0
Accounts payable	(192)	(332)
Fuel cost recovery	11	58
Non-trading derivatives, net	(53)	(40)
Margin deposits, net	21	19
Interest and taxes accrued	(95)	(116)
Net regulatory assets and liabilities	(38)	(3)
Other current assets	(5)	16
Other current liabilities	(37)	(101)
Other assets	19	58
Other liabilities	1	(39)
Other operating activities, net	3	(5)
Net cash provided by operating activities from continuing operations	662	271
Cash Flows from Investing Activities:
Capital expenditures	(664)	(537)
Acquisitions, net of cash acquired	0	(5,987)
Distributions from unconsolidated affiliate in excess of cumulative earnings	7	0
Other investing activities, net	3	(15)
Net cash used in investing activities from continuing operations	(654)	(6,539)
Cash Flows from Financing Activities:
Proceeds from (payments of) commercial paper, net	(828)	2,692
Proceeds from long-term debt, net	0	721
Payments of long-term debt	(63)	(994)
Proceeds from (Repayments of) Lines of Credit	1,050	135
Debt issuance costs	0	(8)
Payment of dividends on Common Stock	(145)	(144)
Payment of dividends on Preferred Stock	(42)	(43)
Other financing activities, net	(4)	(14)
Net cash provided by (used in) financing activities from continuing operations	(32)	2,345
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(24)	(3,923)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	271	4,278
Cash, Cash Equivalents and Restricted Cash at End of Period	247	355
Houston Electric [Member]
Cash Flows from Operating Activities:
Net income (loss)	33	27
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	129	175
Amortization of deferred financing costs	3	3
Deferred income taxes	(1)	(15)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	19	21
Accounts receivable/payable–affiliated companies	(3)	(32)
Inventory	(10)	1
Taxes receivable	0	5
Accounts payable	(2)	2
Non-trading derivatives, net	0	(25)
Interest and taxes accrued	(80)	(58)
Net regulatory assets and liabilities	(11)	(44)
Other current assets	13	13
Other current liabilities	8	(7)
Other assets	0	3
Other liabilities	8	(1)
Other operating activities, net	(3)	(2)
Net cash provided by operating activities from continuing operations	103	66
Cash Flows from Investing Activities:
Capital expenditures	(286)	(258)
Increase in notes receivable–affiliated companies	481	(979)
Other investing activities, net	(3)	0
Net cash used in investing activities from continuing operations	192	(1,237)
Cash Flows from Financing Activities:
Proceeds from long-term debt, net	0	696
Payments of long-term debt	(63)	(175)
Increase (decrease) in notes payable–affiliated companies	133	(1)
Dividend to parent	(385)	(24)
Contribution from parent	0	590
Debt issuance costs	0	(7)
Other financing activities, net	0	(1)
Net cash provided by (used in) financing activities from continuing operations	(315)	1,078
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(20)	(93)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	235	370
Cash, Cash Equivalents and Restricted Cash at End of Period	215	277
CERC Corp [Member]
Cash Flows from Operating Activities:
Net income (loss)	67	138
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	74	73
Depreciation and amortization on assets held for sale	0	4
Amortization of deferred financing costs	3	3
Deferred income taxes	23	21
Goodwill impairment and loss from reclassification to held for sale	132	0
Write-down of natural gas inventory	3	1
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	169	102
Accounts receivable/payable–affiliated companies	0	(18)
Inventory	114	119
Accounts payable	(159)	(255)
Fuel cost recovery	9	58
Non-trading derivatives, net	(54)	(26)
Margin deposits, net	21	19
Interest and taxes accrued	(11)	(8)
Net regulatory assets and liabilities	1	19
Other current assets	(1)	7
Other current liabilities	(13)	(8)
Other assets	18	(12)
Other liabilities	(15)	10
Other operating activities, net	0	1
Net cash provided by operating activities from continuing operations	381	248
Cash Flows from Investing Activities:
Capital expenditures	(176)	(146)
Increase in notes receivable–affiliated companies	0	(106)
Other investing activities, net	(1)	2
Net cash used in investing activities from continuing operations	(177)	(250)
Cash Flows from Financing Activities:
Proceeds from (payments of) commercial paper, net	(172)	11
Dividend to parent	(32)	(20)
Contribution from parent	0	0
Other financing activities, net	(1)	(2)
Net cash provided by (used in) financing activities from continuing operations	(205)	(11)
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(1)	(13)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	2	25
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 1	$ 12