v3.8.0.1
Document and Entity Information - USD ($)
9 Months Ended
Sep. 30, 2017
Oct. 26, 2017
Jun. 30, 2016
Entity Information [Line Items]      
Entity Registrant Name CENTERPOINT ENERGY INC.    
Entity Central Index Key 0001130310    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Document Type 10-Q    
Document Period End Date Sep. 30, 2017    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus Q3    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   431,033,509  
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Public Float     $ 10,273,144,728