Post-retirement and Similar Obligations (Tables)

3 Months Ended

Mar. 31, 2017

Compensation And Retirement Disclosure [Abstract]

Components of Net Periodic Pension and Postretirement Benefits

The components of net periodic benefit cost for pension benefits for the three months ended March 31, 2017 and 2016, respectively, consisted of:

	Three Months Ended
	March 31,
	2017			2016
(Millions)
Service cost	$	11		$	11
Interest cost		35			35
Expected return on plan assets		(50	)		(51	)
Amortization of:
Prior service costs		—			—
Actuarial loss		32			38
Net Periodic Benefit Cost	$	28		$	33

The components of net periodic benefit cost for postretirement benefits for the three months ended March 31, 2017 and 2016, respectively, consisted of:

	Three Months Ended
	March 31,
	2017			2016
(Millions)
Service cost	$	1		$	1
Interest cost		5			6
Expected return on plan assets		(2	)		(3	)
Amortization of:
Prior service costs		(2	)		(2	)
Actuarial loss		1			2
Net Periodic Benefit Cost	$	3		$	4