Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2012

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 September 30,						Nine Months Ended September 30,
	2011			2012			2011			2012
	(in millions)
Interest cost	$	4		$	4		$	12		$	12
Expected return on plan assets	(2		)	(2		)	(6		)	(5		)
Amortization of loss	1			1			1			2
Amortization of transition obligation	1			2			4			5
Net periodic cost	$	4		$	5		$	11		$	14