Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2015

Defined Benefit Plan Disclosure [Line Items]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

CenterPoint Houston’s employees participate in CenterPoint Energy’s postretirement benefit plan. CenterPoint Houston’s net periodic cost includes the following components relating to postretirement benefits:

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
	(in millions)
Service cost	$	1		$	—		$	1		$	—
Interest cost	3			3			6			7
Expected return on plan assets	(1		)	(2		)	(3		)	(3		)
Amortization of prior service credit	(1		)	(1		)	(1		)	(1		)
Amortization of loss	1			1			2			1
Amortization of transition obligation	—			1			—			2
Net periodic cost	$	3		$	2		$	5		$	6