Earnings Per Share (CenterPoint Energy) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Income from continuing operations	$ 531	$ 280
Less: Preferred stock dividend requirement (Note 18)	13	29
Undistributed earnings allocated to preferred shareholders	0	23
Income available to common shareholders from continuing operations - basic	518	228
Add back: Undistributed earnings allocated to preferred shareholders	0	23
Income available to common shareholders from continuing operations - diluted	518	268
Income available to common shareholders from discontinued operations - basic and diluted	0	83
Income available to common shareholders - basic and diluted	518	351
Income available to common shareholders - basic and diluted	$ 518	$ 351
Denominator:
Weighted average common shares outstanding - basic	629,134	551,546
Plus: Incremental shares from assumed conversions:
Weighted average common shares outstanding - diluted	631,304	631,420
Earnings Per Common Share:
Basic earnings per common share - continuing operations (in dollars per share)	$ 0.82	$ 0.41
Basic earnings (loss) per common share - discontinued operations (in dollars per share)	0	0.15
Basic Earnings (Loss) Per Common Share (in dollars per share)	0.82	0.56
Diluted Earnings (Loss) Per Common Share
Diluted earnings per common share - continuing operations (in dollars per share)	0.82	0.43
Diluted earnings (loss) per common share - discontinued operations (in dollars per share)	0	0.13
Diluted Earnings (Loss) Per Common Share (in dollars per share)	$ 0.82	$ 0.56
Restricted Stock
Plus: Incremental shares from assumed conversions:
Restricted stock	2,170	3,114
Series B Preferred Stock
Numerator:
Less: Preferred stock dividend requirement (Note 18)	$ 0	$ 17
Add back: Series B Preferred Stock dividend	$ 0	$ 17
Plus: Incremental shares from assumed conversions:
Preferred Stock	0	35,937
Series C Preferred Stock
Plus: Incremental shares from assumed conversions:
Preferred Stock	0	40,823