Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 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 March 31,
	2012			2013
	(in millions)
Interest cost	$	4		$	3
Expected return on plan assets	(2		)	(1		)
Amortization of loss	1			1
Amortization of transition obligation	1			1
Net periodic cost	$	4		$	4