Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

The table below summarizes the Registrants’ outstanding interest rate hedging activity:

	December 31, 2020		December 31, 2019
Hedging Classification	Notional Principal
	(in millions)
Economic hedge (1)	$	84	$	84

(1)Relates to interest rate derivative instruments at SIGECO.

Fair Value of Derivative Instruments [Table Text Block]

The following tables present information about derivative instruments and hedging activities. The first table provides a balance sheet overview of Derivative Assets and Liabilities as of December 31, 2020 and 2019, while the last table provides a breakdown of the related income statement impacts for the years ending December 31, 2020, 2019 and 2018.

Fair Value of Derivative Instruments and Hedged Items

CenterPoint Energy

		December 31, 2020				December 31, 2019
	Balance Sheet Location	Derivative Assets Fair Value		Derivative Liabilities Fair Value		Derivative Assets Fair Value		Derivative Liabilities Fair Value
		(in millions)
Derivatives not designated as hedging instruments:
Natural gas derivatives (1)	Current Liabilities: Non-trading derivative liabilities	$	—	$	3	$	—	$	7
Natural gas derivatives (1)	Other Liabilities: Non-trading derivative liabilities	—		7		—		15
Interest rate derivatives	Other Liabilities	—		20		—		10
Indexed debt securities derivative (2)	Current Liabilities	—		953		—		893
	Total	$	—	$	983	$	—	$	925

(1)Natural gas contracts are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due. However, the mark-to-market fair value of each natural gas contract is in a liability position with no offsetting amounts

(2)Derivative component of the ZENS obligation that represents the ZENS holder’s option to receive the appreciated value of the reference shares at maturity. See Note 12 for further information.

Income Statement Impact of Derivative Activity [Table Text Block]

Income Statement Impact of Hedge Accounting Activity (CenterPoint Energy)

CenterPoint Energy

		Year Ended December 31,
	Income Statement Location	2020		2019		2018
		(in millions)
Effects of derivatives not designated as hedging instruments on the income statement:
Indexed debt securities derivative	Loss on indexed debt securities	(60)		(292)		(232)
Interest rate derivatives	Gains in Other Income (Expense)	—		—		2
Total CenterPoint Energy		$	(60)	$	(292)	$	(230)

(c) Credit Risk Contingent Features (CenterPoint Energy)

Certain of CenterPoint Energy’s derivative instruments contain provisions that require CenterPoint Energy’s debt to maintain an investment grade credit rating on its long-term unsecured unsubordinated debt from S&P and Moody’s. If CenterPoint Energy’s debt were to fall below investment grade, it would be in violation of these provisions, and the counterparties to the derivative instruments could request immediate payment.

	As of December 31,
	2020		2019
	(in millions)
Aggregate fair value of derivatives with credit-risk-related contingent features in a liability position	$	20	$	10
Fair value of collateral already posted	7		—
Additional collateral required to be posted if credit risk contingent features triggered (1)	3		—

(1)The maximum collateral required if further escalating collateral is triggered would equal the net liability position.