Goodwill and Other Intangibles (CenterPoint Energy and CERC) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Goodwill [Line Items]
Goodwill		$ 4,697		$ 4,882
Goodwill, Impairment Loss		185	$ 0
Finite-Live Intangible Assets [Abstract]
Intangible assets gross carrying amount		68		68
Intangible assets accumulated amortization		(12)		(10)
Net intangible assets		56		58
Amortization of Intangible Assets		1	9
Finite-Lived Intangible Assets Amortization Expense Maturity Schedule [Abstract]
Remaining nine months of 2020		6
2021		6
2022		6
2023		6
2024		5
2025		5
Indiana Electric Integrated [Member]
Goodwill [Line Items]
Goodwill		936		1,121
Goodwill, Impairment Loss		185
Goodwill, Fair Value Disclosure		936
Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill		3,312		3,312
Goodwill, Impairment Loss		0
Corporate and Other [Member]
Goodwill [Line Items]
Goodwill		449		449
Goodwill, Impairment Loss		0
Customer Relationships [Member]
Finite-Live Intangible Assets [Abstract]
Intangible assets gross carrying amount		33		33
Intangible assets accumulated amortization		(5)		(4)
Net intangible assets		28		29
Trade Names [Member]
Finite-Live Intangible Assets [Abstract]
Intangible assets gross carrying amount		16		16
Intangible assets accumulated amortization		(1)		(1)
Net intangible assets		15		15
Construction Backlog [Member]
Finite-Live Intangible Assets [Abstract]
Intangible assets gross carrying amount	[1]	5		5
Intangible assets accumulated amortization	[1]	(4)		(4)
Net intangible assets	[1]	1		1
Operation and maintenance agreements [Member]
Finite-Live Intangible Assets [Abstract]
Intangible assets gross carrying amount	[1]	12		12
Intangible assets accumulated amortization	[1]	(1)		0
Net intangible assets	[1]	11		12
Other [Member]
Finite-Live Intangible Assets [Abstract]
Intangible assets gross carrying amount		2		2
Intangible assets accumulated amortization		(1)		(1)
Net intangible assets		1		1
CERC Corp [Member]
Goodwill [Line Items]
Goodwill		757		757
CERC Corp [Member] | Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill		746		746
CERC Corp [Member] | Corporate and Other [Member]
Goodwill [Line Items]
Goodwill		11		$ 11
Depreciation and amortization expense [Member]
Finite-Live Intangible Assets [Abstract]
Amortization of Intangible Assets		1	0
Non-utility cost of revenues [Member]
Finite-Live Intangible Assets [Abstract]
Amortization of Intangible Assets		1	$ 7
Continuing Operations [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss		$ 185

[1] Amortization expense related to the operation and maintenance agreements and construction backlog is included in Non-utility cost of revenues, including natural gas on CenterPoint Energy’s Condensed Statements of Consolidated Income.