Derivative Instruments (Tables)

6 Months Ended

Jun. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]

The table below summarizes CenterPoint Energy’s and CERC’s current weather hedge activity:

				Three Months Ended June 30,				Six Months Ended June 30,
Jurisdiction	Winter Season	Bilateral Cap		2018		2017		2018			2017
		(in millions)
Certain NGD jurisdictions	2018 – 2019	$	9	$	—	$	—	$	—		$	—
Certain NGD jurisdictions	2017 – 2018	8		—		—		—			—
Total CERC (1)				—		—		—			—
Electric operations’ service territory	2018 – 2019	8		—		—		—			—
Electric operations’ service territory	2017 – 2018	9		—		—		(4		)	—
Electric operations’ service territory	2016 – 2017	9		—		—		—			1
Total CenterPoint Energy (1)				$	—	$	—	$	(4	)	$	1

(1) Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income.

Fair Value of Derivative Instruments [Table Text Block]

The following tables present information about derivative instruments and hedging activities. The first two tables provide a balance sheet overview of Derivative Assets and Liabilities, while the last table provides a breakdown of the related income statement impacts.

Fair Value of Derivative Instruments (CenterPoint Energy and CERC)

		June 30, 2018				December 31, 2017
	Balance Sheet Location	Derivative Assets Fair Value		Derivative Liabilities Fair Value		Derivative Assets Fair Value		Derivative Liabilities Fair Value
Derivatives designated as fair value hedges:		(in millions)
Natural gas derivatives (1) (2) (3)	Current Liabilities: Non-trading derivative liabilities	$	—	$	3	$	13	$	1
Derivatives not designated as hedging instruments:
Natural gas derivatives (1) (2) (3)	Current Assets: Non-trading derivative assets	76		2		114		4
Natural gas derivatives (1) (2) (3)	Other Assets: Non-trading derivative assets	46		—		44		—
Natural gas derivatives (1) (2) (3)	Current Liabilities: Non-trading derivative liabilities	23		64		38		78
Natural gas derivatives (1) (2) (3)	Other Liabilities: Non-trading derivative liabilities	15		41		9		24
Total CERC		160		110		218		107
Indexed debt securities derivative	Current Liabilities	—		641		—		668
Total CenterPoint Energy		$	160	$	751	$	218	$	775

(1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,862 Bcf or a net 268 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of June 30, 2018 and December 31, 2017, respectively.  Certain natural gas contracts hedge basis risk only and lack a fixed price exposure.

(2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $82 million asset and a $130 million asset as of June 30, 2018 and December 31, 2017, respectively, as shown on CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, impacted by collateral netting of $32 million and $19 million, respectively.

(3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.

Offsetting of Natural Gas Derivative Assets and Liabilities [Table Text Block]

Offsetting of Natural Gas Derivative Assets and Liabilities (CenterPoint Energy and CERC)

	June 30, 2018									December 31, 2017
	Gross AmountsRecognized (1)			Gross Amounts Offset in the Consolidated Balance Sheets			Net Amount Presented in the Consolidated Balance Sheets (2)			Gross Amounts Recognized (1)			Gross Amounts Offset in the Consolidated Balance Sheets			Net Amount Presented in the Consolidated Balance Sheets (2)
	(in millions)
Current Assets: Non-trading derivative assets	$	99		$	(25	)	$	74		$	165		$	(55	)	$	110
Other Assets: Non-trading derivative assets	61			(15		)	46			53			(9		)	44
Current Liabilities: Non-trading derivative liabilities	(69		)	43			(26		)	(83		)	63			(20		)
Other Liabilities: Non-trading derivative liabilities	(41		)	29			(12		)	(24		)	20			(4		)
Total	$	50		$	32		$	82		$	111		$	19		$	130

(1) Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.

(2) The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.

Income Statement Impact of Derivative Activity [Table Text Block]

Hedge ineffectiveness is recorded as a component of natural gas expense and primarily results from differences in the location of the derivative instrument and the hedged item. Basis ineffectiveness arises from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the hedge instruments. The impact of natural gas derivatives designated as fair value hedges, the related hedged item, and natural gas derivatives not designated as hedging instruments are presented in the table below.

Income Statement Impact of Derivative Activity (CenterPoint Energy and CERC)

		Three Months Ended June 30,						Six Months Ended  June 30,
	Income Statement Location	2018			2017			2018			2017
Derivatives designated as fair value hedges:		(in millions)
Natural gas derivatives	Gains (Losses) in Non-utility natural gas expense	$	13		$	3		$	13		$	12
Natural gas inventory	Gains (Losses) in Non-utility natural gas expense	(12		)	(4		)	(14		)	(14		)
Total CenterPoint Energy and CERC (1)		$	1		$	(1	)	$	(1	)	$	(2	)
Derivatives not designated as hedging instruments:
Natural gas derivatives	Gains (Losses) in Non-utility revenues	$	11		$	36		$	68		$	132
Natural gas derivatives	Gains (Losses) in Non-utility natural gas expense	(9		)	(9		)	(78		)	(82		)
Total CERC		2			27			(10		)	50
Indexed debt securities derivative	Gains (Losses) in Other Income (Expense)	(254		)	(13		)	(272		)	(23		)
Total CenterPoint Energy		$	(252	)	$	14		$	(282	)	$	27

(1) Hedge ineffectiveness results from the basis ineffectiveness discussed above, and excludes the impact to natural gas expense from timing ineffectiveness.  Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity.  As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on natural gas expense.

Disclosure of Credit Derivatives [Table Text Block]

CenterPoint Energy and CERC enter into financial derivative contracts containing material adverse change provisions.  These provisions could require CenterPoint Energy or CERC to post additional collateral if the S&P or Moody’s credit ratings of CenterPoint Energy, Inc. or its subsidiaries, including CERC Corp., are downgraded. 

CenterPoint Energy and CERC

	June 30, 2018		December 31, 2017
	(in millions)
Aggregate fair value of derivatives containing material adverse change provisions in a net liability position	$	2	$	2
Fair value of collateral already posted	—		—
Additional collateral required to be posted if credit risk contingent features triggered	1		2