Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2013

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,
	2012			2013			2012			2013
	(in millions)
Interest cost	$	4		$	4		$	8		$	7
Expected return on plan assets	(1		)	(2		)	(3		)	(3		)
Amortization of loss	—			1			1			2
Amortization of transition obligation	2			1			3			2
Net periodic cost	$	5		$	4		$	9		$	8