Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2017

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,
	2017		2016		2017		2016
	(in millions)
Interest cost	$	1	$	1	$	2	$	2
Amortization of prior service cost	1		—		1		—
Net periodic cost (1)	$	2	$	1	$	3	$	2

(1) Net periodic cost in this table is before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes.