Background and Basis of Presentation (Details)	Jun. 30, 2018 state shares
Enable Midstream Partners [Member]
Ownership percentage of equity method investment	54.00%
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Preferred units held | shares	14,520,000	[1]
Natural Gas Distribution [Member]
Number of states in which entity operates	6
Energy Services [Member]
Number of states in which entity operates	33

[1] The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both June 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.