CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 248	$ 496
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	982	749
Amortization of deferred financing costs	34	18
Deferred income taxes	33	185
Unrealized gain on marketable securities	(66)	(104)
Loss on indexed debt securities	316	59
Write-down of natural gas inventory	2	0
Equity in earnings of unconsolidated affiliate, net of distributions	(15)	(199)
Pension contributions	(67)	(46)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	355	216
Inventory	(10)	(52)
Taxes receivable	(38)	30
Accounts payable	(262)	(137)
Fuel cost recovery	53	(30)
Non-trading derivatives, net	63	(53)
Margin deposits, net	2	(49)
Interest and taxes accrued	(53)	2
Net regulatory assets and liabilities	44	(135)
Other current assets	11	18
Other current liabilities	16	19
Other assets	(3)	(3)
Other liabilities	24	28
Other, net	10	16
Net cash provided by operating activities	1,679	1,028
Cash Flows from Investing Activities:
Capital expenditures	(1,121)	(994)
Acquisitions, net of cash acquired	0	(132)
Distributions from unconsolidated affiliate in excess of cumulative earnings	30	223
Proceeds from sale of marketable securities	398	0
Other, net	19	6
Net cash used in investing activities	(674)	(897)
Cash Flows from Financing Activities:
Increase (decrease) in short-term borrowings, net	(39)	13
Payments of commercial paper, net	(1,551)	(428)
Proceeds from long-term debt, net	997	1,096
Payments of long-term debt	(368)	(597)
Debt issuance costs	(36)	(13)
Payment of dividends on Common Stock	(360)	(346)
Proceeds from issuance of Series A Preferred Stock, net	790	0
Distribution to ZENS note holders	(398)	0
Other, net	(5)	(4)
Net cash used in financing activities	(970)	(279)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	35	(148)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	296	381
Cash, Cash Equivalents and Restricted Cash at End of Period	331	233
Cash and Cash Equivalents at Beginning of Period	260
Cash and Cash Equivalents at End of Period	293
Houston Electric [Member]
Cash Flows from Operating Activities:
Net income	296	223
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	737	525
Amortization of deferred financing costs	8	10
Deferred income taxes	(24)	29
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	(95)	(131)
Accounts receivable/payable–affiliated companies	(12)	(49)
Inventory	(10)	(3)
Taxes receivable	(9)	6
Accounts payable	(6)	105
Interest and taxes accrued	(50)	(28)
Net regulatory assets and liabilities	(66)	(149)
Other current assets	13	8
Other current liabilities	(9)	25
Other assets	4	1
Other liabilities	16	(1)
Other, net	(5)	(4)
Net cash provided by operating activities	788	567
Cash Flows from Investing Activities:
Capital expenditures	(678)	(603)
Decrease in notes receivable–affiliated companies	0	29
Other, net	15	5
Net cash used in investing activities	(663)	(569)
Cash Flows from Financing Activities:
Proceeds from long-term debt, net	398	298
Payments of long-term debt	(368)	(347)
Decrease in notes payable–affiliated companies	15	0
Dividend to parent	(123)	(87)
Debt issuance costs	(4)	(3)
Contribution from parent	0	0
Other, net	0	0
Net cash used in financing activities	(82)	(139)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	43	(141)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	274	381
Cash, Cash Equivalents and Restricted Cash at End of Period	317	240
Cash and Cash Equivalents at Beginning of Period	238
Cash and Cash Equivalents at End of Period	279
CERC Corp [Member]
Cash Flows from Operating Activities:
Net income	175	239
Less: Income from discontinued operations, net of tax	140	124
Income from continuing operations	35	115
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	222	202
Amortization of deferred financing costs	7	7
Deferred income taxes	6	69
Write-down of natural gas inventory	2	0
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	449	346
Accounts receivable/payable–affiliated companies	0	(1)
Inventory	1	(49)
Accounts payable	(261)	(227)
Fuel cost recovery	53	(30)
Non-trading derivatives, net	60	(51)
Margin deposits, net	2	(49)
Interest and taxes accrued	(9)	(13)
Net regulatory assets and liabilities	73	(28)
Other current assets	7	16
Other current liabilities	24	(5)
Other assets	5	5
Other liabilities	(2)	4
Other, net	0	1
Net cash provided by operating activities from continuing operations	674	312
Net cash provided by operating activities from discontinued operations	176	0
Net cash provided by operating activities	850	312
Cash Flows from Investing Activities:
Capital expenditures	(411)	(373)
Acquisitions, net of cash acquired	0	(132)
Other, net	5	2
Net cash used in investing activities from continuing operations	(406)	(503)
Net cash provided by investing activities from discontinued operations	47	223
Net cash used in investing activities	(359)	(280)
Cash Flows from Financing Activities:
Increase (decrease) in short-term borrowings, net	(39)	13
Payments of commercial paper, net	(800)	(40)
Proceeds from long-term debt, net	599	298
Decrease in notes payable–affiliated companies	(570)	0
Dividend to parent	(286)	(337)
Debt issuance costs	(5)	(4)
Contribution from parent	600	38
Other, net	(1)	0
Net cash used in financing activities from continuing operations	(502)	(32)
Net cash provided by financing activities from discontinued operations	0	0
Net cash used in financing activities	(502)	(32)
Net Decrease in Cash and Cash Equivalents	(11)	0
Cash and Cash Equivalents at Beginning of Period	12	1
Cash and Cash Equivalents at End of Period	$ 1	$ 1