Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019		Dec. 31, 2019	Dec. 31, 2018
Interest, net of capitalized interest			$ 196	$ 231
Income tax refunds, net			4	142
Accounts payable related to capital expenditures			195	173
ROU assets obtained in exchange for lease liabilities (1)			14	42	[1]
Beneficial conversion feature			32
Amortization of Beneficial Conversion Feature	$ (9)	$ 0	(9)	0
Cash and cash equivalents	168		168			$ 241
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	194	332	194	332		271	$ 4,278
Prepaid expenses and other current assets [Member]
Restricted cash	26		26			30
Houston Electric [Member]
Interest, net of capitalized interest			93	113
Income tax refunds, net			0	73
Accounts payable related to capital expenditures			76	86
ROU assets obtained in exchange for lease liabilities (1)			0	1	[1]
Cash and cash equivalents	151		151			216
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	170	293	170	293		235	370
Houston Electric [Member] | Prepaid expenses and other current assets [Member]
Restricted cash	19		19			19
CERC Corp [Member]
Interest, net of capitalized interest			55	55
Income tax refunds, net			0	3
Accounts payable related to capital expenditures			87	72
ROU assets obtained in exchange for lease liabilities (1)			5	28	[1]
Cash and cash equivalents	1		1			2
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	1	$ 5	1	$ 5		2	$ 25
CERC Corp [Member] | Prepaid expenses and other current assets [Member]
Restricted cash	$ 0		$ 0			$ 0

[1] 2019 includes the transition impact of adoption of ASU 2016-02 Leases.