Short-Term Borrowings and Long-term Debt (Details) $ in Millions		3 Months Ended
		Mar. 31, 2020 USD ($) day	Dec. 31, 2019 USD ($)
Line of Credit Facility [Abstract]
Size of credit facility		$ 5,100
Number of days until commercial paper maturity | day		60
VCC [Member]
Line of Credit Facility [Abstract]
Size of credit facility	[1]	$ 200
Credit facility swing line sublimit		40
Letters of credit swing line sublimit		80
Parent Company [Member]
Line of Credit Facility [Abstract]
Size of credit facility		3,300
VUHI [Member]
Line of Credit Facility [Abstract]
Size of credit facility	[2]	400
Credit facility swing line sublimit		10
Letters of credit swing line sublimit		20
Houston Electric [Member]
Debt Instruments [Abstract]
General mortgage bonds used as collateral		68	$ 68
Line of Credit Facility [Abstract]
Size of credit facility		300
CERC Corp [Member]
Line of Credit Facility [Abstract]
Size of credit facility		900
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		1,050	0
Revolving Credit Facility [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]	0	0
Revolving Credit Facility [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]	900	0
Revolving Credit Facility [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]	150	0
Revolving Credit Facility [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		0	0
Revolving Credit Facility [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 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]	0.565
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]	0.590
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]	0.504
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]	0.534
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]	0.436
Line of Credit [Member] | CERC Corp [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[7]	1.25%
Letter of Credit [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 7	7
Letter of Credit [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]	0	0
Letter of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]	6	6
Letter of Credit [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]	0	0
Letter of Credit [Member] | SIGECO [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		20
Letter of Credit [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		0	0
Letter of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		1	1
Commercial Paper [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		1,450	2,278
Commercial Paper [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]	$ 0	$ 0
Weighted average interest rate of debt	[3]	0.00%	0.00%
Commercial Paper [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]	$ 1,169	$ 1,633
Weighted average interest rate of debt	[4]	2.17%	1.95%
Commercial Paper [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]	$ 76	$ 268
Weighted average interest rate of debt	[5]	2.19%	2.08%
Commercial Paper [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 0	$ 0
Weighted average interest rate of debt		0.00%	0.00%
Commercial Paper [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 205	$ 377
Weighted average interest rate of debt		2.80%	1.94%
Maximum [Member] | Letter of Credit [Member] | Vectren [Member]
Line of Credit Facility [Abstract]
Long-term line of credit		$ 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.