CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 146	$ 147
Investment in marketable securities	848	871
Accounts receivable, less allowance for credit losses	780	676
Accrued unbilled revenues, less allowance for credit losses	343	505
Natural gas and coal inventory	67	203
Materials and supplies	310	297
Taxes receivable	79	82
Prepaid expenses and other current assets	646	139
Total current assets	3,219	2,920
Property, Plant and Equipment:
Property, plant and equipment	32,991	32,514
Less: accumulated depreciation and amortization	10,252	10,152
Property, plant and equipment, net	22,739	22,362
Other Assets:
Goodwill	4,697	4,697
Regulatory assets	3,795	2,094
Investment in unconsolidated affiliates	853	783
Preferred units – unconsolidated affiliate	363	363
Other non-current assets	240	252
Total other assets	9,948	8,189
Total Assets	35,906	33,471
Current Liabilities:
Short-term borrowings	0	24
Current portion of VIE Securitization Bonds long-term debt	212	211
Indexed debt, net	13	15
Current portion of other long-term debt	1,563	1,669
Indexed debt securities derivative	927	953
Accounts payable	797	853
Taxes accrued	229	265
Interest accrued	119	145
Dividends accrued	0	136
Customer deposits	120	119
Non-trading derivative liabilities	2	3
Other current liabilities	344	432
Total current liabilities	4,326	4,825
Other Liabilities:
Deferred income taxes, net	3,687	3,603
Non-trading derivative liabilities	14	27
Benefit obligations	675	680
Regulatory liabilities	3,407	3,448
Other non-current liabilities	1,033	1,019
Total other liabilities	8,816	8,777
Long-term Debt:
VIE Securitization Bonds, net	499	536
Other long-term debt, net	13,549	10,985
Total long-term debt, net	14,048	11,521
Commitments and Contingencies (Note 14)
Shareholders' Equity :
Preferred stock	2,363	2,363
Common stock	6	6
Additional paid-in capital	6,916	6,914
Retained Earnings (Accumulated Deficit)	(482)	(845)
Accumulated other comprehensive income (loss)	(87)	(90)
Stockholders' Equity Attributable to Parent, Total	8,716	8,348
Total Liabilities and Shareholders’ Equity	35,906	33,471
Variable Interest Entity, Primary Beneficiary [Member]
Current Assets:
Cash and cash equivalents	142	139
Accounts receivable, less allowance for credit losses	24	23
Prepaid expenses and other current assets	16	15
Other Assets:
Regulatory assets	597	633
Houston Electric [Member]
Current Assets:
Cash and cash equivalents	143	139
Accounts receivable, less allowance for credit losses	263	268
Accrued unbilled revenues, less allowance for credit losses	83	113
Accounts and notes receivable–affiliated companies	674	7
Materials and supplies	202	195
Prepaid expenses and other current assets	32	47
Total current assets	1,397	769
Property, Plant and Equipment:
Property, plant and equipment	13,889	13,593
Less: accumulated depreciation and amortization	3,967	3,930
Property, plant and equipment, net	9,922	9,663
Other Assets:
Regulatory assets	828	848
Other non-current assets	38	36
Total other assets	866	884
Total Assets	12,185	11,316
Current Liabilities:
Current portion of VIE Securitization Bonds long-term debt	212	211
Current portion of other long-term debt	300	402
Accounts payable	333	281
Accounts and notes payable–affiliated companies	41	96
Taxes accrued	103	158
Interest accrued	53	71
Other current liabilities	115	117
Total current liabilities	1,157	1,336
Other Liabilities:
Deferred income taxes, net	1,051	1,041
Benefit obligations	75	75
Regulatory liabilities	1,187	1,252
Other non-current liabilities	95	95
Total other liabilities	2,408	2,463
Long-term Debt:
VIE Securitization Bonds, net	499	536
Other long-term debt, net	4,957	3,870
Total long-term debt, net	5,456	4,406
Commitments and Contingencies (Note 14)
Shareholders' Equity :
Common stock	0	0
Additional paid-in capital	2,548	2,548
Retained Earnings (Accumulated Deficit)	616	563
Accumulated other comprehensive income (loss)	0	0
Stockholders' Equity Attributable to Parent, Total	3,164	3,111
Total Liabilities and Shareholders’ Equity	12,185	11,316
Houston Electric [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Current Assets:
Cash and cash equivalents	142	139
Accounts receivable, less allowance for credit losses	24	23
Prepaid expenses and other current assets	16	15
Other Assets:
Regulatory assets	597	633
CERC Corp [Member]
Current Assets:
Cash and cash equivalents	1	1
Accounts receivable, less allowance for credit losses	349	233
Accrued unbilled revenues, less allowance for credit losses	167	260
Accounts and notes receivable–affiliated companies	11	8
Natural gas and coal inventory	27	121
Materials and supplies	64	58
Prepaid expenses and other current assets	381	26
Total current assets	1,000	707
Property, Plant and Equipment:
Property, plant and equipment	9,070	8,972
Less: accumulated depreciation and amortization	2,466	2,414
Property, plant and equipment, net	6,604	6,558
Other Assets:
Goodwill	757	757
Regulatory assets	1,947	220
Other non-current assets	48	66
Total other assets	2,752	1,043
Total Assets	10,356	8,308
Current Liabilities:
Short-term borrowings	0	24
Accounts payable	273	296
Accounts and notes payable–affiliated companies	48	50
Taxes accrued	90	74
Interest accrued	30	28
Customer deposits	76	76
Other current liabilities	137	178
Total current liabilities	654	726
Other Liabilities:
Deferred income taxes, net	632	584
Benefit obligations	83	83
Regulatory liabilities	1,242	1,226
Other non-current liabilities	678	694
Total other liabilities	2,635	2,587
Long-term Debt:
Total long-term debt, net	4,349	2,428
Commitments and Contingencies (Note 14)
Shareholders' Equity :
Common stock	0	0
Additional paid-in capital	2,046	2,046
Retained Earnings (Accumulated Deficit)	662	511
Accumulated other comprehensive income (loss)	10	10
Stockholders' Equity Attributable to Parent, Total	2,718	2,567
Total Liabilities and Shareholders’ Equity	$ 10,356	$ 8,308