CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash Flows from Operating Activities:
Net income	$ 634	$ 248
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	987	982
Amortization of deferred financing costs	22	34
Amortization of intangible assets in non-utility cost of revenues	19	0
Deferred income taxes	8	33
Unrealized gain on marketable securities	(206)	(66)
Loss on indexed debt securities	216	316
Write-down of natural gas inventory	5	2
Equity in earnings of unconsolidated affiliates, net of distributions	13	(15)
Pension contributions	(94)	(67)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	521	355
Inventory	(85)	(10)
Taxes receivable	(69)	(38)
Accounts payable	(646)	(262)
Fuel cost recovery	68	53
Non-trading derivatives, net	(66)	63
Margin deposits, net	(33)	2
Interest and taxes accrued	(89)	(53)
Net regulatory assets and liabilities	(101)	44
Other current assets	31	11
Other current liabilities	(118)	16
Other assets	81	(3)
Other liabilities	(22)	24
Other operating activities, net	10	10
Net cash provided by operating activities	1,086	1,679
Cash Flows from Investing Activities:
Capital expenditures	(1,822)	(1,121)
Acquisitions, net of cash acquired	(5,991)	0
Distributions from unconsolidated affiliate in excess of cumulative earnings	0	30
Proceeds from sale of marketable securities	0	398
Other investing activities, net	38	19
Net cash used in investing activities	(7,775)	(674)
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	0	(39)
Proceeds from (payments of) commercial paper, net	1,584	(1,551)
Proceeds from long-term debt, net	2,916	997
Payments of long-term debt	(1,225)	(368)
Debt issuance costs	(19)	(36)
Payment of dividends on Common Stock	(433)	(360)
Payment of dividends on Preferred Stock	(101)	0
Proceeds from issuance of Series A Preferred Stock, net	0	790
Distribution to ZENS note holders	0	(398)
Other financing activities, net	(14)	(5)
Net cash provided by (used in) financing activities	2,708	(970)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(3,981)	35
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	4,278	296
Cash, Cash Equivalents and Restricted Cash at End of Period	297	331
Houston Electric [Member]
Cash Flows from Operating Activities:
Net income	312	296
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	519	737
Amortization of deferred financing costs	8	8
Deferred income taxes	(39)	(24)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	(84)	(95)
Accounts receivable/payable–affiliated companies	(7)	(12)
Inventory	(9)	(10)
Taxes receivable	5	(9)
Accounts payable	3	(6)
Non-trading derivatives, net	(25)	0
Interest and taxes accrued	(28)	(50)
Net regulatory assets and liabilities	(58)	(66)
Other current assets	15	13
Other current liabilities	(3)	(9)
Other assets	8	4
Other liabilities	(13)	16
Other operating activities, net	(9)	(5)
Net cash provided by operating activities	595	788
Cash Flows from Investing Activities:
Capital expenditures	(744)	(678)
Increase in notes receivable–affiliated companies	(772)	0
Other investing activities, net	12	15
Net cash used in investing activities	(1,504)	(663)
Cash Flows from Financing Activities:
Proceeds from long-term debt, net	696	398
Payments of long-term debt	(390)	(368)
Increase (decrease) in notes payable–affiliated companies	(1)	15
Dividend to parent	(100)	(123)
Contribution from parent	590	0
Debt issuance costs	(8)	(4)
Other financing activities, net	(1)	0
Net cash provided by (used in) financing activities	786	(82)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(123)	43
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	370	274
Cash, Cash Equivalents and Restricted Cash at End of Period	247	317
CERC Corp [Member]
Cash Flows from Operating Activities:
Net income	159	175
Less: Income from discontinued operations, net of tax	0	140
Income from continuing operations	159	35
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	228	222
Amortization of deferred financing costs	8	7
Deferred income taxes	26	6
Write-down of natural gas inventory	5	2
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	653	449
Accounts receivable/payable–affiliated companies	(9)	0
Inventory	(47)	1
Taxes receivable	(4)	0
Accounts payable	(458)	(261)
Fuel cost recovery	68	53
Non-trading derivatives, net	(60)	60
Margin deposits, net	(33)	2
Interest and taxes accrued	(23)	(9)
Net regulatory assets and liabilities	(1)	73
Other current assets	11	7
Other current liabilities	(9)	24
Other assets	(3)	5
Other liabilities	2	(2)
Net cash provided by operating activities from continuing operations	513	674
Net cash provided by operating activities from discontinued operations	0	176
Net cash provided by operating activities	513	850
Cash Flows from Investing Activities:
Capital expenditures	(546)	(411)
Increase in notes receivable–affiliated companies	27	0
Other investing activities, net	4	5
Net cash used in investing activities from continuing operations	(515)	(406)
Net cash provided by investing activities from discontinued operations	0	47
Net cash used in investing activities	(515)	(359)
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	0	(39)
Proceeds from (payments of) commercial paper, net	100	(800)
Proceeds from long-term debt, net	0	599
Increase (decrease) in notes payable–affiliated companies	0	(570)
Dividend to parent	(119)	(286)
Contribution from parent	0	600
Debt issuance costs	0	(5)
Other financing activities, net	(2)	(1)
Net cash used in financing activities from continuing operations	(21)	(502)
Net cash provided by financing activities from discontinued operations	0	0
Net cash provided by (used in) financing activities	(21)	(502)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(23)	(11)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	25	12
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 2	$ 1