Unconsolidated Affiliate (CenterPoint Energy and CERC) - Summarized Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Revenues	$ 1,742	$ 1,575	$ 4,289	$ 3,742
Depreciation and amortization	327	297	634	579
Operating income	296	235	749	452
Net income attributable to Enable common units	221	59	555	(1,169)
Equity in earnings (loss) of unconsolidated affiliates, net	67	43	175	(1,432)
Current assets	5,179		5,179		$ 2,920
Current liabilities	3,369		3,369		4,825
CenterPoint Energy's equity method investment in Enable	882		882		783
Enable Midstream Partners
Schedule of Equity Method Investments [Line Items]
Revenues	787	515	1,757	1,163
Cost of sales, excluding depreciation and amortization	426	177	945	403
Depreciation and amortization	103	105	209	209
Goodwill and long-lived assets impairments	0	0	0	28
Operating income	124	80	330	226
Net income attributable to Enable common units	79	35	234	138
CenterPoint Energy’s interest	42	19	125	74
Basis difference amortization (1)	25	24	50	36
Loss on dilution, net of proportional basis difference recognition	0	0	0	(1)
Impairment of CenterPoint Energy’s equity method investment in Enable	0	0	0	(1,541)
Equity in earnings (loss) of unconsolidated affiliates, net	67	$ 43	175	$ (1,432)
Current assets	475		475		381
Non-current assets	11,284		11,284		11,348
Current liabilities	1,317		1,317		582
Non-current liabilities	3,249		3,249		4,052
Non-controlling interest	25		25		26
Preferred equity	362		362		362
Accumulated other comprehensive loss	(3)		(3)		(6)
Enable partners' equity	6,809		6,809		6,713
CenterPoint Energy’s ownership interest in Enable partners’ equity	3,651		3,651		3,601
CenterPoint Energy’s basis difference (1)	(2,770)		(2,770)		(2,819)
CenterPoint Energy's equity method investment in Enable	$ 881		$ 881		$ 782