Reportable Segments (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020 USD ($) state	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) state	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Revenues		$ 1,622	$ 1,658	$ 5,364	$ 5,545
Equity in earnings from investment in Enable		(67)	77	(1,499)	213
Net income (loss)		127	251	(791)	545
Net income (loss) from Discontinued Operations		(6)	19	(182)	89
Net income (loss)		121	270	(973)	634
Assets		32,705		32,705		$ 35,529
Total Assets Classified as Held For Use, Current and Noncurrent		32,705		32,705		33,565
Total Assets Classified as Held For Sale, Current and Noncurrent		0		0		1,964
Enable Midstream Partners [Member]
Segment Reporting Information [Line Items]
Revenues		596	699	1,759	2,229
Equity in earnings from investment in Enable		(67)	77	(1,499)	213
Impairment of CenterPoint Energy's equity method investment in Enable		0	0	1,541	0
Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	828	859	2,186	2,313
Equity in earnings from investment in Enable		0	0	0	0
Net income (loss)		157	185	281	315
Houston Electric T&D [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		243	231	573	547
Houston Electric T&D [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		128	83	301	196
Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Revenues		157	165	414	388
Equity in earnings from investment in Enable		0	0	0	0
Net income (loss)		$ 31	34	$ (121)	41
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Number of States in which the Entity Performs Gas Delivery Services | state		48		48
Revenues		$ 560	541	$ 2,519	2,629
Equity in earnings from investment in Enable		0	0	0	0
Net income (loss)		5	6	242	149
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0	0	0
Equity in earnings from investment in Enable	[2]	(67)	77	(1,499)	213
Net income (loss)	[2]	(62)	50	(1,165)	124
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		77	93	245	215
Equity in earnings from investment in Enable		0	0	0	0
Net income (loss)		(4)	(24)	(28)	(84)
Operating Segments [Member] | Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Assets		11,296		11,296		11,264
Operating Segments [Member] | Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Assets		3,142		3,142		3,168
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		14,297		14,297		14,105
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets		805		805		2,473
Operating Segments [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Assets		3,165		3,165		2,555
Houston Electric [Member]
Segment Reporting Information [Line Items]
Revenues		828	859	2,182	2,310
Net income (loss)		157	185	277	312
Assets		11,296		11,296		11,262
Houston Electric [Member] | Houston Electric T&D [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues			231		547
Houston Electric [Member] | Houston Electric T&D [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues			83		196
CERC Corp [Member]
Segment Reporting Information [Line Items]
Revenues		426	420	1,920	2,158
Net income (loss)		(6)	(10)	142	102
Net income (loss) from Discontinued Operations		2	3	(66)	57
Net income (loss)		(4)	(7)	76	159
Assets		7,779		7,779		8,512
Total Assets Classified as Held For Use, Current and Noncurrent		7,779		7,779		7,608
Total Assets Classified as Held For Sale, Current and Noncurrent		$ 0		$ 0		904
CERC Corp [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Number of States in which the Entity Performs Gas Delivery Services | state		48		48
Revenues		$ 422	415	$ 1,910	2,152
Net income (loss)		1	5	155	134
CERC Corp [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		4	5	10	6
Net income (loss)		(7)	$ (15)	(13)	$ (32)
CERC Corp [Member] | Operating Segments [Member] | Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Assets		0		0		0
CERC Corp [Member] | Operating Segments [Member] | Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Assets		0		0		0
CERC Corp [Member] | Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		7,809		7,809		7,698
CERC Corp [Member] | Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets		0		0		0
CERC Corp [Member] | Operating Segments [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Assets		$ (30)		$ (30)		$ (90)

[1] Houston Electric T&D’s revenues from major external customers are as follows (CenterPoint Energy and Houston Electric): Three Months Ended September 30,Nine Months Ended September 30,2020201920202019(in millions)Affiliates of NRG$243 $231 $573 $547 Affiliates of Vistra Energy Corp.128 83 301 196 

[2] Includes the impairment of CenterPoint Energy’s equity method investment in Enable of $1,541 million recorded during the nine months ended September 30, 2020 and CenterPoint Energy’s interest in Enable’s $225 million impairment on an equity method investment during the three and nine months ended September 30, 2020.