Short-Term Borrowings and Long-term Debt (Details) $ in Millions		3 Months Ended	6 Months Ended
		Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($) day	Jun. 02, 2020 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility [Abstract]
Size of credit facility		$ 5,100	$ 5,100
Number of days until commercial paper maturity | day			60
VCC [Member]
Line of Credit Facility [Abstract]
Size of credit facility	[1]	200	$ 200
Credit facility swing line sublimit		40	40
Letters of credit swing line sublimit		80	80
Parent Company [Member]
Line of Credit Facility [Abstract]
Size of credit facility		3,300	3,300
VUHI [Member]
Line of Credit Facility [Abstract]
Size of credit facility	[2]	400	400
Credit facility swing line sublimit		10	10
Letters of credit swing line sublimit		20	20
Houston Electric [Member]
Debt Instrument [Line Items]
General mortgage bonds used as collateral		68	68		$ 68
Line of Credit Facility [Abstract]
Size of credit facility		300	300
CERC Corp [Member]
Line of Credit Facility [Abstract]
Size of credit facility		900	900
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		0	0		0
Revolving Credit Facility [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]	0	0		0
Revolving Credit Facility [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]	0	0		0
Revolving Credit Facility [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]	0	0		0
Revolving Credit Facility [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		0	0		0
Revolving Credit Facility [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 0	$ 0		0
Line of Credit [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[1]		65.00%
Ratio of indebtedness to net capital	[1],[6]	0.568	0.568
Line of Credit [Member] | VCC [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[1],[7]		1.25%
Line of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[8]		65.00%
Ratio of indebtedness to net capital	[6]	0.524	0.524
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)			70.00%
System restoration costs threshold for increase in permitted debt to EBITDA covenant ratio			$ 100
Consecutive period for system restoration costs to exceed $100 million (in months)			12
Line of Credit [Member] | Parent Company [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[7]		1.50%
Line of Credit [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[2]		65.00%
Ratio of indebtedness to net capital	[2],[6]	0.513	0.513
Line of Credit [Member] | VUHI [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[2],[7]		1.125%
Line of Credit [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[8]		65.00%
Ratio of indebtedness to net capital	[6]	0.539	0.539
Line of Credit [Member] | Houston Electric [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[7]		1.25%
Line of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant			65.00%
Ratio of indebtedness to net capital	[6]	0.507	0.507
Line of Credit [Member] | CERC Corp [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[7]		1.125%
Letter of Credit [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 9	$ 9		7
Letter of Credit [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]	0	0		0
Letter of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]	8	8		6
Letter of Credit [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]	0	0		0
Letter of Credit [Member] | SIGECO [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		7	7
Letter of Credit [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		0	0		0
Letter of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		1	1		1
Commercial Paper [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		780	780		2,278
Commercial Paper [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]	$ 0	$ 0		$ 0
Weighted average interest rate of debt	[3]	0.00%	0.00%		0.00%
Commercial Paper [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]	$ 316	$ 316		$ 1,633
Weighted average interest rate of debt	[4]	0.38%	0.38%		1.95%
Commercial Paper [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]	$ 232	$ 232		$ 268
Weighted average interest rate of debt	[5]	0.28%	0.28%		2.08%
Commercial Paper [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 0	$ 0		$ 0
Weighted average interest rate of debt		0.00%	0.00%		0.00%
Commercial Paper [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 232	$ 232		$ 377
Weighted average interest rate of debt		0.26%	0.26%		1.94%
General Mortgage Bonds Due 2050 [Member] | Houston Electric [Member]
Debt Instrument [Line Items]
Principal amount of debt issued				$ 300
Interest rate of debt				2.90%
Long-term Debt				$ 296
Variable rate term loan [Member] | CenterPoint Energy [Member]
Debt Instrument [Line Items]
Principal amount of debt issued		$ 1,000	$ 1,000
Repayments of Debt		300
Variable rate term loan [Member] | VUHI [Member]
Debt Instrument [Line Items]
Repayments of Debt		300
Variable rate term loan [Member] | VCC [Member]
Debt Instrument [Line Items]
Repayments of Debt		200
Senior Notes [Member] | VUHI [Member]
Debt Instrument [Line Items]
Interest rate of debt				6.28%
Repayments of Debt		100
Maximum [Member] | Letter of Credit [Member] | Vectren [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 50	$ 50

[1] This credit facility was issued by VCC, is guaranteed by Vectren and includes a $40 million swing line sublimit and an $80 million letter of credit sublimit.

[2] This credit facility was issued by VUHI, is guaranteed by SIGECO, Indiana Gas and VEDO and includes a $10 million swing line sublimit and a $20 million letter of credit sublimit. This credit facility backstops VUHI’s commercial paper program.

[3] This credit facility was issued by VCC and is guaranteed by Vectren.

[4] CenterPoint Energy’s outstanding commercial paper generally has maturities of 60 days or less.

[5] This credit facility was issued by VUHI and is guaranteed by SIGECO, Indiana Gas and VEDO.

[6] As defined in the revolving credit facility agreements, excluding Securitization Bonds.

[7] Based on current credit ratings.

[8] For CenterPoint Energy and Houston Electric, the financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive 12-month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification.