Post-retirement and Similar Obligations (Tables)

9 Months Ended

Sep. 30, 2020

Retirement Benefits [Abstract]

Components of Net Periodic Pension and Postretirement Benefits

The components of net periodic benefit cost for pension benefits for the three and nine months ended September 30, 2020 and 2019, respectively, consisted of:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
(Millions)
Service cost	$	12	$	10	$	35	$	30
Interest cost	27		33		81		98
Expected return on plan assets	(50)		(48)		(150)		(144)
Amortization of:
Prior service costs	—		—		—		(1)
Actuarial loss	31		28		94		85
Net Periodic Benefit Cost	$	20	$	23	$	60	$	68

The components of net periodic benefit cost for postretirement benefits for the three and nine months ended September 30, 2020 and 2019, respectively, consisted of: 

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
(Millions)
Service cost	$	1	$	1	$	2	$	2
Interest cost	4		4		10		12
Expected return on plan assets	(2)		(1)		(6)		(5)
Amortization of:
Prior service costs	(3)		(3)		(7)		(7)
Actuarial loss	—		—		1		(1)
Net Periodic Benefit Cost	$	—	$	1	$	—	$	1