Reportable Segments - Revenues by Products and Services (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Operating revenues	$ 8,352	$ 7,418	$ 7,564
CenterPoint Energy
Segment Reporting Information [Line Items]
Operating revenues	8,352	7,418	7,564
CenterPoint Energy | Electric delivery
Segment Reporting Information [Line Items]
Operating revenues	3,158	2,941	3,019
CenterPoint Energy | Retail electric sales
Segment Reporting Information [Line Items]
Operating revenues	559	515	486
CenterPoint Energy | Wholesale electric sales
Segment Reporting Information [Line Items]
Operating revenues	46	14	14
CenterPoint Energy | Retail gas sales
Segment Reporting Information [Line Items]
Operating revenues	4,157	3,462	3,563
CenterPoint Energy | Gas transportation and processing
Segment Reporting Information [Line Items]
Operating revenues	12	15	33
CenterPoint Energy | Energy products and services
Segment Reporting Information [Line Items]
Operating revenues	420	471	449
Houston Electric
Segment Reporting Information [Line Items]
Operating revenues	3,134	2,911	2,990
Houston Electric | Electric delivery
Segment Reporting Information [Line Items]
Operating revenues	3,134	2,911	2,990
Houston Electric | Retail electric sales
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
Houston Electric | Wholesale electric sales
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
Houston Electric | Retail gas sales
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
Houston Electric | Gas transportation and processing
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
Houston Electric | Energy products and services
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
CERC Corp
Segment Reporting Information [Line Items]
Operating revenues	3,248	2,763	3,018
CERC Corp | Electric delivery
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
CERC Corp | Retail electric sales
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
CERC Corp | Wholesale electric sales
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
CERC Corp | Retail gas sales
Segment Reporting Information [Line Items]
Operating revenues	3,069	2,594	2,831
CERC Corp | Gas transportation and processing
Segment Reporting Information [Line Items]
Operating revenues	12	15	33
CERC Corp | Energy products and services
Segment Reporting Information [Line Items]
Operating revenues	$ 167	$ 154	$ 154