Background and Basis of Presentation (Details)	9 Months Ended
	Sep. 30, 2018 state shares
Enable Midstream Partners [Member]
Ownership percentage of equity method investment	54.00%	[1],[2]
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Preferred units held | shares	14,520,000	[2],[3]
Natural Gas Distribution [Member]
Number of states in which entity operates	6
Energy Services [Member]
Number of states in which entity operates	33
Enable GP, LLC [Member] | CenterPoint Energy [Member]
Management rights ownership percentage	50.00%	[4],[5]
Incentive distribution right	40.00%	[5],[6]

[1] Excludes the Enable Series A Preferred Units owned by CenterPoint Energy.

[2] Includes Enable Series A Preferred Units held directly by CenterPoint Energy and common units held indirectly through CNP Midstream.

[3] The carrying amount of the Enable Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both September 30, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion.

[4] Enable is controlled jointly by CenterPoint Energy and OGE. Sale of CenterPoint Energy’s or OGE’s ownership interests in Enable GP to a third party is subject to mutual rights of first offer and first refusal, and CenterPoint Energy is not permitted to dispose of less than all of its interest in Enable GP.

[5] Includes interests held through CNP Midstream.

[6] Enable is expected to pay a minimum quarterly distribution of $0.2875 per common unit on its outstanding common units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to Enable GP and its affiliates, within 60 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per common unit in any quarter, Enable GP will receive increasing percentages or incentive distributions rights, up to 50%, of the cash Enable distributes in excess of that amount. In certain circumstances Enable GP will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election. To date, no incentive distributions have been made.