Revenue Recognition (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019		Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts		$ 2,539		$ 2,126
Derivative income (loss)		1,076		1,103
Other	[1]	(10)		(36)
Revenues		3,531		3,155
Houston Electric T&D [Member]
Disaggregation of Revenue [Line Items]
Revenues	[2]	689		751
Indiana Electric Integrated [Member]
Disaggregation of Revenue [Line Items]
Revenues		83		0
Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,389		1,143
Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,182		1,257
Infrastructure Services [Member]
Disaggregation of Revenue [Line Items]
Revenues		146		0
Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenues		42		4
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues		(74)		(38)
Intersegment Eliminations [Member] | Houston Electric T&D [Member]
Disaggregation of Revenue [Line Items]
Revenues		0		0
Intersegment Eliminations [Member] | Indiana Electric Integrated [Member]
Disaggregation of Revenue [Line Items]
Revenues		0		0
Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues		(10)		(10)
Intersegment Eliminations [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenues		(64)		(28)
Intersegment Eliminations [Member] | Infrastructure Services [Member]
Disaggregation of Revenue [Line Items]
Revenues		0		0
Intersegment Eliminations [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenues		0		0
Reportable Subsegments [Member] | Houston Electric T&D [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	690		761
Derivative income (loss)	[3]	3		(4)
Other	[1],[3]	(4)		(6)
Revenues	[3]	689		751
Reportable Subsegments [Member] | Indiana Electric Integrated [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	83	[4]	0
Derivative income (loss)	[3]	0	[4]	0
Other	[1],[3]	0	[4]	0
Revenues	[3]	83	[4]	0
Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	1,406	[4]	1,186
Derivative income (loss)	[3]	0	[4]	0
Other	[1],[3]	(7)	[4]	(33)
Revenues	[3]	1,389	[4]	1,143
Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[5]	173		178
Derivative income (loss)	[5]	1,073		1,107
Other	[1],[5]	0		0
Revenues	[5]	1,182		1,257
Reportable Subsegments [Member] | Infrastructure Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[5]	146	[4]	0
Derivative income (loss)	[5]	0	[4]	0
Other	[1],[5]	0	[4]	0
Revenues	[5]	146	[4]	0
Reportable Subsegments [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[5]	41	[4]	1
Derivative income (loss)	[5]	0	[4]	0
Other	[1],[5]	1	[4]	3
Revenues	[5]	42	[4]	4
Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	(10)	[4]	(10)
Derivative income (loss)	[5]	(64)		(28)
Revenues		(74)		(38)
Houston Electric [Member]
Disaggregation of Revenue [Line Items]
Revenues		686		755
Houston Electric [Member] | Reportable Subsegments [Member] | Houston Electric T&D [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		690		761
Other	[6]	(4)		(6)
Revenues		686		755
CERC Corp [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		1,372		1,364
Derivative income (loss)		1,073		1,107
Other	[7]	(3)		(33)
Revenues		2,368		2,400
CERC Corp [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,185		1,143
CERC Corp [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenues		1,182		1,257
CERC Corp [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenues		1		0
CERC Corp [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues		(74)		(38)
CERC Corp [Member] | Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues		(10)		(10)
CERC Corp [Member] | Intersegment Eliminations [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenues		(64)		(28)
CERC Corp [Member] | Intersegment Eliminations [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenues		0		0
CERC Corp [Member] | Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[8]	1,198		1,186
Derivative income (loss)	[8]	0		0
Other	[7],[8]	(3)		(33)
Revenues	[8]	1,185		1,143
CERC Corp [Member] | Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[9]	173		178
Derivative income (loss)	[9]	1,073		1,107
Other	[7],[9]	0		0
Revenues	[9]	1,182		1,257
CERC Corp [Member] | Reportable Subsegments [Member] | Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[9]	1		0
Derivative income (loss)	[9]	0		0
Other	[7],[9]	0		0
Revenues	[9]	1		0
CERC Corp [Member] | Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[8]	(10)		(10)
Derivative income (loss)	[9]	(64)		(28)
Revenues		$ (74)		$ (38)

[1] Primarily consists of income from ARPs 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.

[2] Houston Electric T&D revenues from major customers are as follows: Three Months Ended March 31, 2019 2018 (in millions)Affiliates of NRG $151 $161Affiliates of Vistra Energy Corp. 54 54

[3] Reflected in Utility revenues in the Condensed Statements of Consolidated Income

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

[5] Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income.

[6] Primarily consists of income from ARPs 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.

[7] Primarily consists of income from ARPs 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.

[8] Reflected in Utility revenues in the Condensed Statements of Consolidated Income.

[9] Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income.