Revenue Recognition Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts		$ 2,141		$ 2,227
Other	[1]	26		2
Revenues		2,167		2,229
Lease Income		1		2
Houston Electric T&D [Member]
Disaggregation of Revenue [Line Items]
Revenues	[2]	638		689
Indiana Electric Integrated [Member]
Disaggregation of Revenue [Line Items]
Revenues		129		83
Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,318		1,415
Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenues		82		42
Reportable Subsegments [Member] | Houston Electric T&D [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		638		690
Other	[1]	0		(1)
Revenues		638		689
Reportable Subsegments [Member] | Indiana Electric Integrated [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		129		83	[3]
Other	[1]	0		0	[3]
Revenues		129		83	[3]
Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		1,293		1,413	[3]
Other	[1]	25		2	[3]
Revenues		1,318		1,415	[3]
Reportable Subsegments [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		81		41	[3]
Other	[1]	1		1	[3]
Revenues		82		42	[3]
Houston Electric [Member]
Disaggregation of Revenue [Line Items]
Revenues		634		686
Houston Electric [Member] | Reportable Subsegments [Member] | Houston Electric T&D [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		638		690
Other		(4)		(4)
Revenues		634		686
CERC Corp [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		984		1,206
Other	[4]	27		6
Revenues		1,011		1,212
CERC Corp [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,008		1,211
CERC Corp [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenues		3		1
CERC Corp [Member] | Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		981		1,205
Other		27	[4]	6
Revenues		1,008		1,211
CERC Corp [Member] | Reportable Subsegments [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		3		1
Other	[4]	0
Revenues		$ 3		$ 1

[1] Primarily consists of income from ARPs, weather hedge gains (losses) and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. The Registrants recognize ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period. Total lease income was $1 million and $2 million for the three months ended March 31, 2020 and 2019, respectively.

[2] CenterPoint Energy’s Houston Electric T&D’s revenues from major external customers are as follows:     Three Months Ended March 31,     2020   2019     (in millions) Affiliates of NRG   $ 156
  $ 151
Affiliates of Vistra Energy Corp.   81
  54

[3] Reflects revenues from Vectren subsidiaries for the period from February 1, 2019 to March 31, 2019.

[4] Primarily consists of income from ARPs, weather hedge gains (losses) and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. The Registrants recognize ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period. Lease income was not significant for the three months ended March 31, 2020 and 2019.