Earnings Per Share (CenterPoint Energy) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Recognition of beneficial conversion feature	$ 0	$ 32	$ 0
Numerator:
Income (loss) from continuing operations	668	483	515
Less: Preferred stock dividend requirement	95	176	117
Less: Amortization of beneficial conversion feature	0	32	0
Less: Undistributed earnings allocated to preferred shareholders	0	0	0
Income (loss) available to common shareholders from continuing operations - basic	573	307	398
Income (loss) available to common shareholders from continuing operations - diluted	573	307	398
Income (loss) available to common shareholders from discontinued operations - basic	818	(1,256)	276
Income (loss) available to common shareholders from discontinued operations - diluted	818	(1,256)	276
Income (loss) available to common shareholders - basic	1,391	(949)	674
Income (loss) available to common shareholders - diluted	$ 1,391	$ (949)	$ 674
Denominator:
Weighted average common shares outstanding - basic	592,933	531,031	502,050
Weighted average common shares outstanding - diluted	609,938	531,031	505,157
Earnings (loss) per common share:
Basic earnings per common share - continuing operations (in dollars per share)	$ 0.97	$ 0.58	$ 0.79
Basic earnings (loss) per common share - discontinued operations (in dollars per share)	1.38	(2.37)	0.55
Basic Earnings (Loss) Per Common Share (in dollars per share)	2.35	(1.79)	1.34
Earnings Per Share, Diluted [Abstract]
Diluted earnings per common share - continuing operations (in dollars per share)	0.94	0.58	0.79
Diluted earnings (loss) per common share - discontinued operations (in dollars per share)	1.34	(2.37)	0.54
Diluted Earnings (Loss) Per Common Share (in dollars per share)	$ 2.28	$ (1.79)	$ 1.33
Restricted stock
Denominator:
Restricted stock	5,181	0	3,107
Anti-dilutive Incremental Shares Excluded from Denominator for Diluted Earnings (Loss) Computation:
Amount of antidilutive securities excluded from computation of earnings per share	0	3,690	0
Series B Preferred Stock
Numerator:
Less: Preferred stock dividend requirement	$ 95	$ 144	$ 117
Anti-dilutive Incremental Shares Excluded from Denominator for Diluted Earnings (Loss) Computation:
Amount of antidilutive securities excluded from computation of earnings per share	23,906	35,922	34,354
Series C Preferred Stock
Denominator:
Preferred Stock	11,824	0	0
Anti-dilutive Incremental Shares Excluded from Denominator for Diluted Earnings (Loss) Computation:
Amount of antidilutive securities excluded from computation of earnings per share	0	23,807	0