Reportable Business Segments (Tables)

12 Months Ended

Dec. 31, 2015

Segment Reporting [Abstract]

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

Financial data for business segments and products and services are as follows:

	Revenues from External Customers		Inter-segment Revenues			Depreciation and Amortization		Operating Income (Loss)			Total Assets			Expenditures for Long- Lived Assets
	(in millions)
As of and for the year ended December 31, 2015:
Natural Gas Distribution	$	2,603	$	29		$	222	$	273		$	5,657		$	601
Energy Services	1,924		33			5		42			857			5
Midstream Investments (1)	—		—			—		—			2,594			—
Other	—		—			—		(2		)	789			—
Reconciling Eliminations	—		(62		)	—		—			(744		)	—
Consolidated	$	4,527	$	—		$	227	$	313		$	9,153		$	606
As of and for the year ended December 31, 2014:
Natural Gas Distribution	$	3,271	$	30		$	201	$	287		$	5,464		$	525
Energy Services	3,095		84			5		52			978			3
Midstream Investments (1)	—		—			—		—			4,521			—
Other	1		—			—		(4		)	1,045			—
Reconciling Eliminations	—		(114		)	—		—			(964		)	—
Consolidated	$	6,367	$	—		$	206	$	335		$	11,044		$	528
As of and for the year ended December 31, 2013:
Natural Gas Distribution	$	2,837	$	26		$	185	$	263		$	4,976		$	430
Energy Services	2,374		27			5		13			895			3
Interstate Pipelines (2) (3)	133		53			20		72			—			29
Field Services (3)	178		18			20		73			—			16
Midstream Investments (1)	—		—			—		—			4,518			—
Other	—		—			—		(20		)	1,139			—
Reconciling Eliminations	—		(124		)	—		—			(996		)	—
Consolidated	$	5,522	$	—		$	230	$	401		$	10,532		$	478

(1) Midstream Investments’ equity earnings (losses) are as follows:

	Year Ended December 31,
	2015			2014		2013
	(in millions)
Enable (1)	$	(1,633	)	$	303	$	173
SESH	—			5		8
Total	$	(1,633	)	$	308	$	181

(1) These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $1,846 million during the year ended December 31, 2015. This impairment is offset by $213 million of earnings for the year ended December 31, 2015.

Midstream Investments’ total assets are as follows:

	December 31, 2015		December 31, 2014
	(in millions)
Enable	$	2,594	$	4,520
SESH	—		1
Total	$	2,594	$	4,521

(2) Interstate Pipelines recorded equity income of $7 million in the year ended December 31, 2013 from its interest in SESH, a jointly-owned pipeline. These amounts are included in Equity in earnings of unconsolidated affiliates under the Other Income (Expense) caption.  As discussed above, effective May 1, 2013, CenterPoint Energy reports equity earnings associated with its interest in Enable and equity earnings associated with its interest in SESH under its Midstream Investments segment, and no longer has an Interstate Pipelines reporting segment prospectively.

(3) Results reflected in the year ended December 31, 2013 represent only January 2013 through April 2013.

Revenue from External Customers by Products and Services [Table Text Block]

	Year Ended December 31,
Revenues by Products and Services:	2015		2014		2013
	(in millions)
Retail gas sales	$	3,725	$	5,049	$	4,150
Wholesale gas sales	657		1,159		913
Gas transportation and processing	26		38		345
Energy products and services	119		121		114
Total	$	4,527	$	6,367	$	5,522

Midstream Investments [Table Text Block]

Midstream Investments’ equity earnings (losses) are as follows:

	Year Ended December 31,
	2015			2014		2013
	(in millions)
Enable (1)	$	(1,633	)	$	303	$	173
SESH	—			5		8
Total	$	(1,633	)	$	308	$	181

(1) These amounts include CERC’s share of Enable’s impairment of goodwill and long-lived assets and the impairment of CERC’s equity method investment in Enable totaling $1,846 million during the year ended December 31, 2015. This impairment is offset by $213 million of earnings for the year ended December 31, 2015.

Midstream Investments’ total assets are as follows:

	December 31, 2015		December 31, 2014
	(in millions)
Enable	$	2,594	$	4,520
SESH	—		1
Total	$	2,594	$	4,521