CONDENSED STATEMENTS OF CONSOLIDATED INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Utility revenues	$ 2,484	$ 2,073
Non-utility revenues	63	94
Total	2,547	2,167
Expenses:
Utility natural gas, fuel and purchased power	935	609
Non-utility cost of revenues, including natural gas	40	64
Operation and maintenance	669	674
Depreciation and amortization	307	282
Taxes other than income taxes	143	136
Goodwill Impairment	0	185
Total	2,094	1,950
Operating Income	453	217
Other Income (Expense):
Loss on marketable securities	(23)	(144)
Gain on indexed debt securities	26	135
Interest expense and other finance charges	(113)	(139)
Interest expense on Securitization Bonds	(6)	(8)
Equity in earnings (loss) of unconsolidated affiliates, net	108	(1,475)
Other income (expense), net	(8)	14
Total	(16)	(1,617)
Income (Loss) from Continuing Operations before Income Taxes	437	(1,400)
Income tax expense (benefit)	74	(347)
Income (Loss) from Continuing Operations	363	(1,053)
Income (Loss) from Discontinued Operations	0	(146)
Net Income (Loss)	363	(1,199)
Income allocated to preferred shareholders	29	29
Income (Loss) Available to Common Shareholders	334	(1,228)
Supplemental Income Statement Elements [Abstract]
Income tax benefit from discontinued operations	$ 0	$ 17
Basic Earnings (Loss) Per Common Share [Abstract]
Basic earnings (loss) per common share - continuing operations	$ 0.56	$ (2.15)
Basic earnings (loss) per common share - discontinued operations	0	(0.29)
Basic Earnings (Loss) Per Common Share	0.56	(2.44)
Earnings Per Share, Diluted [Abstract]
Diluted earnings (loss) per common share - continuing operations	0.56	(2.15)
Diluted earnings (loss) per common share - discontinued operations	0	(0.29)
Diluted Earnings (Loss) Per Common Share	$ 0.56	$ (2.44)
Weighted Average Common Shares Outstanding, Basic	551,546,000	502,388,000
Weighted Average Common Shares Outstanding, Diluted	631,420,000	502,388,000
Houston Electric [Member]
Revenues:
Total	$ 684	$ 634
Expenses:
Operation and maintenance	373	359
Depreciation and amortization	141	129
Taxes other than income taxes	63	64
Total	577	552
Operating Income	107	82
Other Income (Expense):
Interest expense and other finance charges	(45)	(41)
Interest expense on Securitization Bonds	(6)	(8)
Other income (expense), net	5	5
Total	(46)	(44)
Income (Loss) from Continuing Operations before Income Taxes	61	38
Income tax expense (benefit)	8	5
Net Income (Loss)	53	33
CERC Corp [Member]
Revenues:
Utility revenues	1,168	996
Non-utility revenues	9	15
Total	1,177	1,011
Expenses:
Utility natural gas, fuel and purchased power	623	472
Non-utility cost of revenues, including natural gas	2	6
Operation and maintenance	198	209
Depreciation and amortization	80	74
Taxes other than income taxes	56	50
Total	959	811
Operating Income	218	200
Other Income (Expense):
Interest expense and other finance charges	(24)	(30)
Other income (expense), net	(1)	(4)
Total	(25)	(34)
Income (Loss) from Continuing Operations before Income Taxes	193	166
Income tax expense (benefit)	42	35
Income (Loss) from Continuing Operations	151	131
Income (Loss) from Discontinued Operations	0	(64)
Net Income (Loss)	151	67
Supplemental Income Statement Elements [Abstract]
Income tax benefit from discontinued operations	$ 0	$ 11