Reportable Business Segments (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues		$ 2,798	$ 2,186	$ 6,329	$ 5,341
Operating Income (Loss)		287	187	532	438
Equity in earnings from investment in Enable		74	58	136	127
Assets		34,189		34,189		$ 27,009
Total regulatory assets		2,248		2,248		2,044
Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	765	854	1,454	1,605
Operating Income (Loss)		169	181	253	296
Houston Electric T&D [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		165	169	316	330
Houston Electric T&D [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		59	59	113	113
Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Revenues		140	0	223	0
Operating Income (Loss)		25	0	16	0
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		650	487	2,039	1,630
Operating Income (Loss)		47	7	214	163
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		838	841	2,020	2,098
Operating Income (Loss)		29	15	62	(11)
Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues		325	0	471	0
Operating Income (Loss)		24	0	8	0
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0	0	0
Operating Income (Loss)	[2]	0	0	0	0
Equity in earnings from investment in Enable		74	58	136	127
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		80	4	122	8
Operating Income (Loss)		(7)	(16)	(21)	(10)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(28)	(27)	(102)	(65)
Assets		(2,982)		(2,982)		(652)
Intersegment Eliminations [Member] | Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Intersegment Eliminations [Member] | Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		(10)	(8)	(20)	(18)
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(17)	(19)	(81)	(47)
Intersegment Eliminations [Member] | Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues		(1)	0	(1)	0
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0	0	0
Intersegment Eliminations [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Operating Segments [Member] | Houston Electric T&D [Member]
Segment Reporting Information [Line Items]
Assets		11,478		11,478		10,509
Operating Segments [Member] | Indiana Electric Integrated [Member]
Segment Reporting Information [Line Items]
Assets	[3]	2,989		2,989		0
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets	[3]	12,946		12,946		6,956
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,262		1,262		1,558
Operating Segments [Member] | Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Assets	[3]	1,303		1,303		0
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets		2,915		2,915		2,482
Operating Segments [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Assets	[3],[4]	4,278		4,278		6,156
Pension and Other Postretirement Plans Costs [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total regulatory assets		639		639		665
Houston Electric [Member]
Segment Reporting Information [Line Items]
Revenues		765	854	1,451	1,609
Operating Income (Loss)		169	181	250	300
Assets		11,478		11,478		10,507
Total regulatory assets		1,016		1,016		1,124
Houston Electric [Member] | Houston Electric T&D [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		0	169	0	330
Houston Electric [Member] | Houston Electric T&D [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		0	59	0	113
CERC Corp [Member]
Segment Reporting Information [Line Items]
Revenues		1,342	1,328	3,710	3,728
Operating Income (Loss)		58	22	254	153
Assets		7,815		7,815		8,214
Total regulatory assets		207		207		258
CERC Corp [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		503	487	1,688	1,630
Operating Income (Loss)		28	7	192	163
CERC Corp [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		839	841	2,021	2,098
Operating Income (Loss)		29	15	62	(11)
CERC Corp [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		0	0	1	0
Operating Income (Loss)		1	0	0	1
CERC Corp [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(26)	(27)	(100)	(65)
Assets		(398)		(398)		(366)
CERC Corp [Member] | Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		(10)	(8)	(20)	(18)
CERC Corp [Member] | Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(16)	(19)	(80)	(47)
CERC Corp [Member] | Intersegment Eliminations [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues		0	$ 0	0	$ 0
CERC Corp [Member] | Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		6,843		6,843		6,956
CERC Corp [Member] | Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,262		1,262		1,558
CERC Corp [Member] | Operating Segments [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Assets	[3]	$ 108		$ 108		66
Cash and Cash Equivalents [Member]
Segment Reporting Information [Line Items]
Short-term Investments						$ 3,900

[1] Houston Electric T&D revenues from major external customers are as follows:     Three Months Ended June 30,   Six Months Ended June 30,     2019   2018   2019   2018     (in millions) Affiliates of NRG   $ 165
  $ 169
  $ 316
  $ 330
Affiliates of Vistra Energy Corp.   59
  59
  113
  113

[2] CenterPoint Energy’s Midstream Investments’ equity earnings, net are as follows:     Three Months Ended June 30,   Six Months Ended June 30,     2019   2018   2019   2018     (in millions) Enable   $ 74
  $ 58
  $ 136
  $ 127

[3] Total assets by reportable segment include assets acquired in the Merger, which are based on preliminary estimates and allocations and are subject to change. See Note 3.

[4] Includes pension and other postemployment-related regulatory assets of $639 million and $665 million, respectively, as of June 30, 2019 and December 31, 2018. Additionally, total assets as of December 31, 2018 included $3.9 billion of temporary investments included in Cash and cash equivalents on CenterPoint Energy’s Consolidated Balance Sheets.