Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest, net of capitalized interest		$ 363	$ 378	$ 406
Income taxes (refunds), net		89	15	(104)
Accounts payable related to capital expenditures		201	144	87
Capital distribution associated with the Internal Spin		0	0	0
Cash and cash equivalents	[1]	4,231	260
Total cash, cash equivalents and restricted cash shown in Statements of Consolidated Cash Flows		4,278	296	381	$ 300
Other, net [Member]
Interest income		28	2	1
Cash and Cash Equivalents [Member]
Temporary investments		3,900
Prepaid Expenses and Other Current Assets [Member]
Restricted cash		46	35
Other Noncurrent Assets [Member]
Restricted cash		1	1
Houston Electric [Member]
Interest, net of capitalized interest		200	205	209
Income taxes (refunds), net		154	76	128
Accounts payable related to capital expenditures		124	104	65
Capital distribution associated with the Internal Spin		0	0	0
Cash and cash equivalents	[2]	335	238
Total cash, cash equivalents and restricted cash shown in Statements of Consolidated Cash Flows		370	274	381	$ 299
Houston Electric [Member] | Other, net [Member]
Interest Income, Other		4	2	1
Houston Electric [Member] | Prepaid Expenses and Other Current Assets [Member]
Restricted cash		34	35
Houston Electric [Member] | Other Noncurrent Assets [Member]
Restricted cash		1	1
CERC Corp [Member]
Interest, net of capitalized interest		105	116	116
Income taxes (refunds), net		3	4	3
Accounts payable related to capital expenditures		80	56	35
Capital distribution associated with the Internal Spin		1,473	0	$ 0
Cash and cash equivalents		14	12
Total cash, cash equivalents and restricted cash shown in Statements of Consolidated Cash Flows		25	12
CERC Corp [Member] | Prepaid Expenses and Other Current Assets [Member]
Restricted cash		11	0
CERC Corp [Member] | Other Noncurrent Assets [Member]
Restricted cash		0	0
Bond Companies [Member] | Houston Electric [Member]
Cash and cash equivalents		$ 335	$ 230

[1] CenterPoint Energy’s Cash and cash equivalents as of December 31, 2018 included $3.9 billion of temporary investments resulting from the Merger financings. CenterPoint Energy recorded interest income of $28 million, $2 million and $1 million for the years ended December 31, 2018, 2017 and 2016, respectively, in Other, net on CenterPoint Energy’s Statements of Consolidated Income. See Notes 13 and 14 for further details related to the Merger financings.

[2] Houston Electric’s Cash and cash equivalents as of December 31, 2018 and 2017 included $335 million and $230 million, respectively, of cash related to the Bond Companies. Houston Electric recorded interest income of $4 million, $2 million and $1 million for the years ended December 31, 2018, 2017 and 2016, respectively, in Other, net on Houston Electric’s Statement of Consolidated Income.