Employee Benefit Plans Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2013

Compensation and Retirement Disclosure [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

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

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2012		2013		2012		2013
	(in millions)
Interest cost on accumulated benefit obligation	2		1		3		2
Amortization of prior service cost	—		—		1		1
Amortization of loss	1		1		1		1
Net periodic cost	$	3	$	2	$	5	$	4