Employee Benefit Plans (Tables)

9 Months Ended

Sep. 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						Nine Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(in millions)
Service cost	$	1		$	1		$	1		$	1
Interest cost	1			1			3			3
Expected return on plan assets	(1		)	(1		)	(1		)	(1		)
Amortization of prior service cost	—			—			1			—
Net periodic cost (1)	$	1		$	1		$	4		$	3

(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.