Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 23, 2020
Entity Information [Line Items]
Entity Incorporation, State or Country Code	TX
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Registrant Name	CENTERPOINT ENERGY INC.
Entity Central Index Key	0001130310
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		544,821,120
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	1-31447
Entity Tax Identification Number	74-0694415
Entity Address, Address Line One	1111 Louisiana
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77002
City Area Code	713
Local Phone Number	207-1111
Houston Electric [Member]
Entity Information [Line Items]
Entity Incorporation, State or Country Code	TX
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Registrant Name	CENTERPOINT ENERGY HOUSTON ELECTRIC LLC
Entity Central Index Key	0000048732
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Tax Identification Number	22-3865106
Entity Address, Address Line One	1111 Louisiana
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77002
City Area Code	713
Local Phone Number	207-1111
CERC Corp [Member]
Entity Information [Line Items]
Entity Incorporation, State or Country Code	DE
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Registrant Name	CENTERPOINT ENERGY RESOURCES CORP
Entity Central Index Key	0001042773
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Tax Identification Number	76-0511406
Entity Address, Address Line One	1111 Louisiana
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77002
City Area Code	713
Local Phone Number	207-1111
Common Stock, $0.01 Par Value [Member] | New York Stock Exchange [Member]
Entity Information [Line Items]
Trading Symbol	CNP
Title of 12(b) Security	Common Stock, $0.01 par value
Security Exchange Name	NYSE
Common Stock, $0.01 Par Value [Member] | Chicago Stock Exchange [Member]
Entity Information [Line Items]
Trading Symbol	CNP
Title of 12(b) Security	Common Stock, $0.01 par value
Security Exchange Name	CHX
Depositary shares [Member] | New York Stock Exchange [Member]
Entity Information [Line Items]
Trading Symbol	CNP/PB
Title of 12(b) Security	Depositary Shares for 1/20 of 7.00% Series B Mandatory Convertible Preferred Stock, $0.01 par value
Security Exchange Name	NYSE
9.15% First Mortgage Bonds due 2021 [Member] | New York Stock Exchange [Member] | Houston Electric [Member]
Entity Information [Line Items]
Trading Symbol	n/a
Title of 12(b) Security	9.15% First Mortgage Bonds due 2021
Security Exchange Name	NYSE
6.95% General Mortgage Bonds due 2033 [Member] | New York Stock Exchange [Member] | Houston Electric [Member]
Entity Information [Line Items]
Trading Symbol	n/a
Title of 12(b) Security	6.95% General Mortgage Bonds due 2033
Security Exchange Name	NYSE
6.625% Senior Notes due 2037 [Member] | New York Stock Exchange [Member] | CERC Corp [Member]
Entity Information [Line Items]
Trading Symbol	n/a
Title of 12(b) Security	6.625% Senior Notes due 2037
Security Exchange Name	NYSE