Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (Tables)

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of Indexed Debt Securities and Marketable Securities [Table Text Block]

In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received certain TW securities as partial consideration. A subsidiary of CenterPoint Energy holds shares of certain securities detailed in the table below, which are classified as trading securities and are expected to be held to facilitate CenterPoint Energy’s ability to meet its obligation under the ZENS. Unrealized gains and losses resulting from changes in the market value of the ZENS-Related Securities are recorded in CenterPoint Energy’s Condensed Statements of Consolidated Income.

	Shares Held
	June 30, 2018	December 31, 2017
AT&T Common	10,212,945	—
Charter Common	872,503	872,503
Time Common	—	888,392
TW Common	—	7,107,130

As a result, CenterPoint Energy recorded the following during the six months ended June 30, 2018:

	Meredith/Time				AT&T/TW
	(in millions)				(in millions)
Cash payment to ZENS note holders	$	16		Due to ZENS note holders (1)	$	382
Indexed debt – reduction	(4		)	Indexed debt – reduction	(95		)
Indexed debt securities derivative – reduction	(1		)	Indexed debt securities derivative – reduction	(45		)
Loss on indexed debt securities	$	11		Loss on indexed debt securities	$	242

(1)Cash of approximately $382 million was paid to ZENS note holders in July 2018.

CenterPoint Energy’s reference shares for each ZENS consisted of the following:

	June 30, 2018	December 31, 2017
	(in shares)
AT&T Common	0.7185	—
Charter Common	0.061382	0.061382
Time Common	—	0.0625
TW Common	—	0.5