Reportable Business Segments (Tables)

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

Reportable business segments by Registrant are as follows:

	Electric Transmission & Distribution	Natural Gas Distribution	Energy  Services	Midstream Investments	Other Operations
CenterPoint Energy	X	X	X	X	X
Houston Electric	X
CERC		X	X	X	X

Financial data for business segments is as follows:

CenterPoint Energy

	Three Months Ended June 30,
	2018									2017
	Revenues from External Customers			Net Intersegment Revenues			Operating Income (Loss)			Revenues from External Customers			Net Intersegment Revenues			Operating Income
	(in millions)
Electric Transmission & Distribution	$	854	(1)	$	—		$	181		$	752	(1)	$	—		$	171
Natural Gas Distribution	487			8			7			470			7			42
Energy Services	841			19			15			918			13			16
Midstream Investments (2)	—			—			—			—			—			—
Other Operations	4			—			(16		)	3			—			11
Eliminations	—			(27		)	—			—			(20		)	—
Consolidated	$	2,186		$	—		$	187		$	2,143		$	—		$	240

	Six Months Ended June 30,
	2018									2017
	Revenues from External Customers			Net Intersegment Revenues			Operating Income (Loss)			Revenues from External Customers			Net Intersegment Revenues			Operating Income
	(in millions)
Electric Transmission & Distribution	$	1,605	(1)	$	—		$	296		$	1,391	(1)	$	—		$	257
Natural Gas Distribution	1,630			18			163			1,377			16			210
Energy Services	2,098			47			(11		)	2,103			24			51
Midstream Investments (2)	—			—			—			—			—			—
Other Operations	8			—			(10		)	7			—			13
Eliminations	—			(65		)	—			—			(40		)	—
Consolidated	$	5,341		$	—		$	438		$	4,878		$	—		$	531

(1) CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
	(in millions)
Affiliates of NRG	$	169	$	167	$	330	$	319
Affiliates of Vistra Energy Corp.	59		53		113		100

CERC

	Three Months Ended June 30,
	2018							2017
	Revenues from External Customers		Net Intersegment Revenues			Operating Income		Revenues from External Customers			Net Intersegment Revenues			Operating Income
	(in millions)
Natural Gas Distribution	$	487	$	8		$	7	$	470		$	7		$	42
Energy Services	841		19			15		918			13			16
Midstream Investments (2)	—		—			—		—			—			—
Other Operations	—		—			—		(1		)	—			1
Eliminations	—		(27		)	—		—			(20		)	—
Consolidated	$	1,328	$	—		$	22	$	1,387		$	—		$	59

	Six Months Ended June 30,
	2018								2017
	Revenues from External Customers		Net Intersegment Revenues			Operating Income (Loss)			Revenues from External Customers		Net Intersegment Revenues			Operating Income  (Loss)
	(in millions)
Natural Gas Distribution	$	1,630	$	18		$	163		$	1,377	$	16		$	210
Energy Services	2,098		47			(11		)	2,103		24			51
Midstream Investments (2)	—		—			—			—		—			—
Other Operations	—		—			1			—		—			(3		)
Eliminations	—		(65		)	—			—		(40		)	—
Consolidated	$	3,728	$	—		$	153		$	3,480	$	—		$	258

(2) CenterPoint Energy’s and CERC’s Midstream Investments’ equity earnings, net are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
	(in millions)
Enable	$	58	$	59	$	127	$	131

CenterPoint Energy and CERC

	Total Assets
	June 30, 2018							December 31, 2017
	CenterPoint  Energy				CERC			CenterPoint Energy				CERC
	(in millions)
Electric Transmission & Distribution	$	10,430			$	—		$	10,292			$	—
Natural Gas Distribution	6,501				6,501			6,608				6,608
Energy Services	1,256				1,256			1,521				1,521
Midstream Investments	2,451				2,451			2,472				2,472
Other Operations	2,311			(3)	89			2,497			(3)	70
Eliminations	(841		)		(655		)	(654		)		(559		)
Consolidated	$	22,108			$	9,642		$	22,736			$	10,112

(3) Includes pension and other postemployment-related regulatory assets of $577 million and $600 million, respectively, as of June 30, 2018 and December 31, 2017.

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
	(in millions)
Affiliates of NRG	$	169	$	167	$	330	$	319
Affiliates of Vistra Energy Corp.	59		53		113		100

Midstream Investments [Table Text Block]

CenterPoint Energy’s and CERC’s Midstream Investments’ equity earnings, net are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
	(in millions)
Enable	$	58	$	59	$	127	$	131