Equity (CenterPoint Energy) (Details)					1 Months Ended	12 Months Ended
	May 06, 2020 USD ($) $ / shares shares	Apr. 01, 2020 $ / shares	Oct. 01, 2018 USD ($) $ / shares shares	Aug. 22, 2018 USD ($) $ / shares shares	Jul. 31, 2021 shares	Dec. 31, 2021 USD ($) day $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Jul. 20, 2021 shares	May 07, 2021 $ / shares
Cumulative preferred stock, outstanding (in shares) | shares						800,000	2,402,400	1,777,500
Preferred stock, value outstanding						$ 790,000,000	$ 2,363,000,000	$ 1,740,000,000
Income allocated to preferred shareholders						95,000,000	144,000,000	117,000,000
Amortization of beneficial conversion feature						0	32,000,000	0
Income allocated to preferred shareholders						95,000,000	176,000,000	117,000,000
Preferred stock liquidation preference						800	2,402
Proceeds from issuance of common stock						0	672,000,000	0
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance						(90,000,000)	(98,000,000)
Other comprehensive loss from unconsolidated affiliates						3,000,000	(2,000,000)
Prior service cost (2)						1,000,000	0
Actuarial losses (1)						7,000,000	7,000,000
Settlement (2)						4,000,000	0
Reclassification of deferred loss from cash flow hedges realized in net income						2,000,000	0
Reclassification of deferred loss from cash flow hedges to regulatory assets (3)						0	19,000,000
Tax benefit (expense)						(7,000,000)	(4,000,000)
Net current period other comprehensive income (loss)						26,000,000	8,000,000	10,000,000
Ending Balance						(64,000,000)	(90,000,000)	(98,000,000)
Chief Executive Officer
Shares authorized for issuance under long-term incentive plans (in shares) | shares									1,000,000
Chief Executive Officer | Restricted Stock Units (RSUs)
RSUs granted (in shares) | shares					400,000
Remaining shares available to be awarded (in shares) | shares					600,000
Enable Midstream Partners
Undistributed earnings from equity method investments included in retained earnings						0	0
Houston Electric
Amortization of beneficial conversion feature						0	0	0
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance						0	(15,000,000)
Other comprehensive loss from unconsolidated affiliates						0	0
Prior service cost (2)						0	0
Actuarial losses (1)						0	0
Settlement (2)						0	0
Reclassification of deferred loss from cash flow hedges realized in net income						0	0
Reclassification of deferred loss from cash flow hedges to regulatory assets (3)						0	19,000,000
Tax benefit (expense)						0	(4,000,000)
Net current period other comprehensive income (loss)						0	15,000,000	(1,000,000)
Ending Balance						0	0	(15,000,000)
CERC Corp
Amortization of beneficial conversion feature						0	0	0
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance						10,000,000	10,000,000
Other comprehensive loss from unconsolidated affiliates						0	0
Prior service cost (2)						1,000,000	1,000,000
Actuarial losses (1)						0	0
Settlement (2)						0	0
Reclassification of deferred loss from cash flow hedges realized in net income						0	0
Reclassification of deferred loss from cash flow hedges to regulatory assets (3)						0	0
Tax benefit (expense)						(1,000,000)	(1,000,000)
Net current period other comprehensive income (loss)						0	0	5,000,000
Ending Balance						10,000,000	10,000,000	$ 10,000,000
Pension and Other Postretirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Remeasurement of pension and other postretirement plans						16,000,000	(12,000,000)
Pension and Other Postretirement Plans [Member] | Houston Electric
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Remeasurement of pension and other postretirement plans						0	0
Pension and Other Postretirement Plans [Member] | CERC Corp
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Remeasurement of pension and other postretirement plans						$ 0	$ 0
120 Days After Conclusion of Review or Appeal [Member]
Preferred stock redemption price (per share) | $ / shares						$ 1,020
Common Stock
Common stock, dividends declared per share (in dollars per share) | $ / shares						0.6600	$ 0.9000	$ 0.8625
Common stock, dividends paid per share (in dollars per share) | $ / shares						$ 0.6500	0.7400	0.8625
Stock issued (in shares) | shares	41,977,612
Common stock issued upon conversion (in shares) | shares						35,921,441
Shares authorized for issuance under long-term incentive plans (in shares) | shares						14,000,000
Common stock issued per share price | $ / shares	$ 16.08
Proceeds from issuance of common stock	$ 673,000,000
Common Stock | Previous Dividend or Distribution
Common stock, dividends declared per share (in dollars per share) | $ / shares		$ 0.2900
Common Stock | Revised Dividend or Distribution
Common stock, dividends declared per share (in dollars per share) | $ / shares		$ 0.1500
Series A Preferred Stock
Preferred stock, dividends declared per share (in dollars per share) | $ / shares						$ 61.2500	91.8750	30.6250
Preferred stock, dividends paid per share (in dollars per share) | $ / shares						61.2500	$ 61.2500	$ 30.6250
Preferred stock liquidation preference (per share) | $ / shares				$ 1,000		$ 1,000
Cumulative preferred stock, outstanding (in shares) | shares						800,000	800,000	800,000
Preferred stock, value outstanding						$ 790,000,000	$ 790,000,000	$ 790,000,000
Income allocated to preferred shareholders						$ 49,000,000	$ 49,000,000	$ 49,000,000
Stock issued (in shares) | shares				800,000
Proceeds from the issuance of convertible stock				$ 790,000,000
Preferred stock liquidation preference				$ 800,000,000
Preferred stock dividend rate						6.125%
Preferred stock redemption price (per share) | $ / shares						$ 1,000
Preferred stock convertible threshold (in days) | day						120
Series A Preferred Stock | London Interbank Offered Rate (LIBOR)
Preferred stock, basis spread (as a percent)						3.27%
Series A Preferred Stock | 120 Days After Conclusion of Review or Appeal [Member]
Preferred stock redemption percentage liquidation value						102.00%
Series B Preferred Stock
Preferred stock, dividends declared per share (in dollars per share) | $ / shares						$ 35.0000	$ 87.5000	$ 52.5000
Preferred stock, dividends paid per share (in dollars per share) | $ / shares						52.5000	$ 70.0000	$ 52.5000
Preferred stock liquidation preference (per share) | $ / shares			$ 1,000			$ 1,000
Cumulative preferred stock, outstanding (in shares) | shares						0	977,400	977,500
Preferred stock, value outstanding						$ 0	$ 950,000,000	$ 950,000,000
Income allocated to preferred shareholders						46,000,000	68,000,000	68,000,000
Income allocated to preferred shareholders						$ 95,000,000	$ 144,000,000	$ 117,000,000
Stock issued (in shares) | shares			2,550,000
Preferred stock liquidation preference			$ 978,000,000
Preferred stock dividend rate						7.00%
Conversion rate per share (in shares) | shares						36.7677
Preferred stock converted to common stock (in shares) | shares						977,400
Series C Preferred Stock
Preferred stock, dividends declared per share (in dollars per share) | $ / shares						$ 0	$ 0.6100	$ 0
Preferred stock, dividends paid per share (in dollars per share) | $ / shares						0.1600	$ 0.4500	$ 0
Preferred stock liquidation preference (per share) | $ / shares	$ 1,000					$ 1,000				$ 1,000
Cumulative preferred stock, outstanding (in shares) | shares						0	625,000	0
Preferred stock, value outstanding						$ 0	$ 623,000,000	$ 0
Income allocated to preferred shareholders						$ 0	$ 27,000,000	$ 0
Stock issued (in shares) | shares	725,000
Proceeds from the issuance of convertible stock	$ 724,000,000
Preferred stock converted to common stock (in shares) | shares						625,000
Common stock issued upon conversion (in shares) | shares						40,822,990
Conversion price (in dollars per share) | $ / shares										$ 15.31
Depositary Shares
Stock issued (in shares) | shares			19,550,000
Proceeds from the issuance of convertible stock			$ 950,000,000
Depositary share par value (in dollars per share) | $ / shares			$ 50