Related Party Transactions (Houston Electric and CERC) (Tables)

6 Months Ended

Jun. 30, 2018

Related Party Transactions [Abstract]

Schedule of Money Pool Investment and Borrowing [Table Text Block]

The table below summarizes money pool activity:

	June 30, 2018						December 31, 2017
	Houston Electric			CERC			Houston Electric			CERC
	(in millions)
Money pool investments (borrowings) (1)	$	26		$	—		$	(60	)	$	(570	)
Weighted average interest rate	2.00		%	—		%	1.90		%	1.90		%

(1) Included in Accounts and notes receivable (payable)–affiliated companies in the Condensed Consolidated Balance Sheets.

Schedule of Related Party Transactions [Table Text Block]

Amounts charged for these services were as follows and are included primarily in operation and maintenance expenses:

	Three Months Ended June 30,										Six Months Ended June 30,
	2018					2017					2018					2017
	Houston Electric			CERC		Houston Electric			CERC		Houston Electric			CERC		Houston Electric			CERC
	(in millions)
Corporate service charges	$	47		$	35	$	44		$	32	$	91		$	69	$	86		$	63
Net affiliate service charges (billings)	(3		)	3		(4		)	4		(5		)	5		(5		)	5

Houston Electric and CERC paid dividends on their common shares and stock, respectively, to Utility Holding, LLC as follows:

	Three Months Ended June 30,								Six Months Ended June 30,
	2018				2017				2018				2017
	Houston Electric		CERC		Houston Electric		CERC		Houston Electric		CERC		Houston Electric		CERC
	(in millions)
Dividends paid	$	31	$	125	$	10	$	140	$	63	$	211	$	42	$	248

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
	(in millions)
Affiliates of NRG	$	169	$	167	$	330	$	319
Affiliates of Vistra Energy Corp.	59		53		113		100