Short-Term Borrowings and Long-term Debt (Details) $ in Millions				3 Months Ended
		Feb. 08, 2019 USD ($)	Jan. 15, 2019 USD ($)	Mar. 31, 2019 USD ($) day	Dec. 31, 2018 USD ($)
Acquired Long-term Debt [Abstract]
Accrued interest expense				$ 5
Commercial paper issued in connection with the Merger				$ 764
Number of days until commercial paper maturity | day				60
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
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				135	$ 0
Revolving Credit Facility [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]			135
Revolving Credit Facility [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]			0	0
Revolving Credit Facility [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]			$ 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]			0.296
Line of Credit [Member] | VCC [Member] | London Interbank Offered Rate (LIBOR) [Member]
Acquired Long-term Debt [Abstract]
Basis spread on LIBOR	[1],[7]			1.25%
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%
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)				70.00%
Ratio of indebtedness to net capital	[6]			0.572
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]
Acquired Long-term Debt [Abstract]
Basis spread on LIBOR	[7]			1.50%
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]			0.293
Line of Credit [Member] | VUHI [Member] | London Interbank Offered Rate (LIBOR) [Member]
Acquired Long-term Debt [Abstract]
Basis spread on LIBOR	[2],[7]			1.125%
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[2],[7]			1.125%
Letter of Credit [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 11	11
Letter of Credit [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]			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
Letter of Credit [Member] | SIGECO [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]			23
Commercial Paper [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				3,079	210
Commercial Paper [Member] | VCC [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]			$ 0
Weighted average interest rate of debt	[3]			3.74%
Commercial Paper [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[4]			$ 2,683	$ 0
Weighted average interest rate of debt	[4]			2.83%	0.00%
Commercial Paper [Member] | VUHI [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[5]			$ 175
Weighted average interest rate of debt	[5]			2.71%
Long term Debt Excluding ZENS [Member]
Maturities of Long-term Debt [Abstract]
Remaining nine months of 2019				$ 283
2020				831
2021				1,761
2022				4,241
2023				713
2024				684
2025 and thereafter				5,757
Variable rate term loan [Member]
Debt Instruments [Abstract]
Principal amount of debt issued	[9]	$ 25
Interest rate of debt	[9]	3.21%
Maturity date of debt issued	[9]	Sep. 14, 2020
Acquired Long-term Debt [Abstract]
Interest rate of debt	[9]	3.21%
Vectren acquisition [Member] | Commercial Paper [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				1,700
Vectren [Member]
Acquired Long-term Debt [Abstract]
Long-term debt				1,740
Vectren [Member] | Revolving Credit Facility [Member]
Acquired Long-term Debt [Abstract]
Long-term debt	[10]			135
Vectren [Member] | Variable term rate loan 2 [Member]
Acquired Long-term Debt [Abstract]
Long-term debt	[11]			200
Vectren [Member] | First Mortgage Bonds [Member]
Acquired Long-term Debt [Abstract]
Long-term debt	[12]			293
Vectren [Member] | Commercial Paper [Member]
Acquired Long-term Debt [Abstract]
Long-term debt	[13]			175
Vectren [Member] | Senior Notes Due Range 2 [Member]
Acquired Long-term Debt [Abstract]
Long-term debt	[14]			637
Vectren [Member] | Variable rate term loan [Member]
Acquired Long-term Debt [Abstract]
Long-term debt	[15]			300
Houston Electric [Member]
Debt Instruments [Abstract]
General mortgage bonds used as collateral				68	$ 68
Line of Credit Facility [Abstract]
Size of credit facility				300
Houston Electric [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 0	0
Houston Electric [Member] | Line of Credit [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]			0.499
Houston Electric [Member] | Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]
Acquired Long-term Debt [Abstract]
Basis spread on LIBOR	[7]			1.125%
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[7]			1.125%
Houston Electric [Member] | Letter of Credit [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 4	4
Houston Electric [Member] | Commercial Paper [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				0	0
Houston Electric [Member] | General Mortgage Bonds Due 2049 [Member]
Debt Instruments [Abstract]
Principal amount of debt issued			$ 700
Interest rate of debt			4.25%
Maturity date of debt issued			Feb. 01, 2049
Acquired Long-term Debt [Abstract]
Interest rate of debt			4.25%
VUHI [Member]
Acquired Long-term Debt [Abstract]
Intercompany notes payable established as a result of the merger				$ 568
Number of days until commercial paper maturity | day				30
Line of Credit Facility [Abstract]
Number of days until commercial paper maturity | day				30
VUHI [Member] | Senior Notes Due Range 2 [Member]
Acquired Long-term Debt [Abstract]
Long-term debt				$ 532
Indiana Gas [Member] | Senior Notes Due Range 2 [Member]
Acquired Long-term Debt [Abstract]
Long-term debt				96
VCC [Member]
Acquired Long-term Debt [Abstract]
Intercompany notes payable established as a result of the merger				$ 191
Basis spread on LIBOR				70.00%
Line of Credit Facility [Abstract]
Basis spread on LIBOR				70.00%
VCC [Member] | Senior Notes Due Range 2 [Member]
Acquired Long-term Debt [Abstract]
Long-term debt				$ 9
CERC Corp [Member]
Line of Credit Facility [Abstract]
Size of credit facility	[16]			900
CERC Corp [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[17]			$ 0	0
CERC Corp [Member] | Line of Credit [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[16]			65.00%
Ratio of indebtedness to net capital	[6],[16]			0.459
CERC Corp [Member] | Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]
Acquired Long-term Debt [Abstract]
Basis spread on LIBOR	[7],[16]			1.25%
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[7],[16]			1.25%
CERC Corp [Member] | Letter of Credit [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[17]			$ 1	1
CERC Corp [Member] | Commercial Paper [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[17]			$ 221	$ 210
Weighted average interest rate of debt	[17]			2.64%	2.93%
Product Financing Arrangement [Member]
Short-term Debt [Line Items]
Short-term borrowings				$ 0	$ 0
Product Financing Arrangement [Member] | CERC Corp [Member]
Short-term Debt [Line Items]
Short-term borrowings				$ 0	$ 0
Minimum [Member] | Vectren [Member] | First Mortgage Bonds [Member]
Debt Instruments [Abstract]
Interest rate of debt				2.375%
Acquired Long-term Debt [Abstract]
Interest rate of debt				2.375%
Minimum [Member] | Vectren [Member] | Senior Notes Due Range 2 [Member]
Debt Instruments [Abstract]
Interest rate of debt				3.33%
Acquired Long-term Debt [Abstract]
Interest rate of debt				3.33%
Minimum [Member] | VUHI [Member]
Acquired Long-term Debt [Abstract]
Basis spread on LIBOR				70.00%
Line of Credit Facility [Abstract]
Basis spread on LIBOR				70.00%
Maximum [Member] | Letter of Credit [Member] | Vectren [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[3]			$ 50
Maximum [Member] | Vectren [Member] | First Mortgage Bonds [Member]
Debt Instruments [Abstract]
Interest rate of debt				6.72%
Acquired Long-term Debt [Abstract]
Interest rate of debt				6.72%
Maximum [Member] | Vectren [Member] | Senior Notes Due Range 2 [Member]
Debt Instruments [Abstract]
Interest rate of debt				7.08%
Acquired Long-term Debt [Abstract]
Interest rate of debt				7.08%
Maximum [Member] | VUHI [Member]
Acquired Long-term Debt [Abstract]
Basis spread on LIBOR				90.00%
Line of Credit Facility [Abstract]
Basis spread on LIBOR				90.00%

[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. Approximately $1.7 billion was issued to refinance commercial paper used to fund a portion of the cash consideration for the Merger, pay related fees and expenses, pay Vectren’s stub period cash dividend and long-term incentive payments and repay indebtedness of Vectren subsidiaries redeemed at the option of the holder as a result of the closing of the Merger.

[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.

[9] Draw down by VCC on its variable rate term loan.

[10] Represents borrowings under the VCC credit facility, which is guaranteed by Vectren.

[11] Issued by VCC and guaranteed by Vectren. As of March 31, 2019, the term loan was fully drawn upon, exclusive of any potential incremental term loans under the related facility’s accordion feature. The term loan’s interest rate is currently priced at one-month LIBOR, plus a credit spread of 70 basis points.

[12] The first mortgage bonds issued by SIGECO subject SIGECO’s properties to a lien under the related mortgage indenture.

[13] Issued by VUHI with maturities up to 30 days.

[14] Consists of $532 million of senior notes issued by VUHI, $96 million of senior notes issues by Indiana Gas, and $9 million of senior notes issued by VCC. The senior notes issued by VUHI are guaranteed by SIGECO, Indiana Gas and VEDO. The senior notes issued by VCC are guaranteed by Vectren. Immediately subsequent to the Merger, two of CenterPoint Energy’s acquired wholly-owned subsidiaries, VUHI and VCC, made offers to prepay certain outstanding guaranteed senior notes as required pursuant to certain note purchase agreements previously entered into by VUHI and VCC. In turn, VUHI and VCC borrowed $568 million and $191 million, respectively, from CenterPoint Energy to fund note redemptions effected pursuant to these prepayment offers. To fund these prepayments and payments of approximately $5 million of accrued interest, CenterPoint Energy issued approximately $764 million of commercial paper.

[15] Issued by VUHI and guaranteed by SIGECO, Indiana Gas and VEDO. As of March 31, 2019, the term loan was fully drawn upon. The term loan’s interest rate is currently priced at one-month LIBOR, plus a credit spread ranging from 70 to 90 basis points depending on credit rating.

[16] This credit facility was issued by CERC Corp.

[17] This credit facility was issued by CERC Corp.