Reportable Business Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 2,531		$ 1,853
Operating Income (Loss)	188		250
Assets	10,780				10,542
Equity in earnings of unconsolidated affiliates, net	91		5
Investment in unconsolidated affiliates	4,540				4,518
Natural Gas Distribution
Segment Reporting Information [Line Items]
Revenues	1,478		1,043
Operating Income (Loss)	162		139
Assets	5,104				4,976
Energy Services
Segment Reporting Information [Line Items]
Revenues	1,052		588
Operating Income (Loss)	26		7
Assets	1,053				895
Interstate Pipelines
Segment Reporting Information [Line Items]
Revenues			92
Operating Income (Loss)			52
Assets					0
Field Services
Segment Reporting Information [Line Items]
Revenues			130
Operating Income (Loss)			53
Assets					0
Midstream Investments (1)
Segment Reporting Information [Line Items]
Revenues	0	[1]	0	[1]
Operating Income (Loss)	0	[1]	0	[1]
Assets	4,540				4,518
Other
Segment Reporting Information [Line Items]
Revenues	1		0
Operating Income (Loss)	0		(1)
Assets	1,320				1,149
Midstream Partnership [Member]
Segment Reporting Information [Line Items]
Investment in unconsolidated affiliates	4,340				4,319
Midstream Partnership [Member] | Midstream Investments (1)
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated affiliates, net	88
Investment in unconsolidated affiliates	4,340				4,319
CERC Remaining Interest in SESH [Member] | Midstream Investments (1)
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated affiliates, net	3
SESH [Member]
Segment Reporting Information [Line Items]
Investment in unconsolidated affiliates	200				199
SESH [Member] | Midstream Investments (1)
Segment Reporting Information [Line Items]
Investment in unconsolidated affiliates	200				199
Consolidation, Eliminations [Member]
Segment Reporting Information [Line Items]
Assets	(1,237)				(996)
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(41)		(68)
Intersegment Eliminations | Natural Gas Distribution
Segment Reporting Information [Line Items]
Revenues	(9)		(8)
Intersegment Eliminations | Energy Services
Segment Reporting Information [Line Items]
Revenues	(32)		(9)
Intersegment Eliminations | Interstate Pipelines
Segment Reporting Information [Line Items]
Revenues			(40)
Intersegment Eliminations | Field Services
Segment Reporting Information [Line Items]
Revenues			(11)
Intersegment Eliminations | Midstream Investments (1)
Segment Reporting Information [Line Items]
Revenues	0	[1]	0	[1]
Intersegment Eliminations | Other
Segment Reporting Information [Line Items]
Revenues	$ 0		$ 0

[1] Midstream Investments reported equity earnings of $88 million from Enable and $3 million of equity earnings from CenterPoint Energy’s retained interest in SESH for the three months ended March 31, 2014. Included in total assets of Midstream Investments as of March 31, 2014 and December 31, 2013 is $4,340 million and $4,319 million, respectively, related to CenterPoint Energy’s investment in Enable and $200 million and $199 million, respectively, related to CenterPoint Energy’s retained interest in SESH.