RETIREMENT BENEFITS AND ASSETS HELD IN TRUST (Tables)

9 Months Ended

Sep. 30, 2017

Defined Benefit Plans

Defined Benefit Plan Disclosure

Schedule of Net Defined Benefit Cost Components

Net periodic benefit cost for the pension plans, by component, was as follows for the three and nine months ended September 30, 2017 and 2016:

	Three months ended						Nine months ended
	September 30,						September 30,
(in millions)	2017			2016			2017			2016
Service cost	$	2		$	2		$	5		$	5
Interest cost	1			1			3			3
Expected return on plan assets	(1		)	(1		)	(3		)	(3		)
Amortization of unrecognized loss	—			1			1			3
Net pension cost	$	2		$	3		$	6		$	8

Other Postretirement Benefits Plan

Defined Benefit Plan Disclosure

Schedule of Net Defined Benefit Cost Components

Net postretirement benefit plan cost, by component, was as follows for the three and nine months ended September 30, 2017 and 2016:

	Three months ended						Nine months ended
	September 30,						September 30,
(in millions)	2017			2016			2017			2016
Service cost	$	2		$	2		$	6		$	6
Interest cost	1			1			2			2
Expected return on plan assets	(1		)	(1		)	(2		)	(2		)
Net postretirement cost	$	2		$	2		$	6		$	6