Post-retirement and Similar Obligations (Tables)

9 Months Ended

Sep. 30, 2021

Retirement Benefits [Abstract]

Components of Net Periodic Pension and Post-retirement Benefits

The components of net periodic benefit cost for pension benefits for the three and nine months ended September 30, 2021 and 2020, respectively, consisted of:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
(Millions)
Service cost	$	10	$	12	$	30	$	35
Interest cost	22		27		66		81
Expected return on plan assets	(50)		(50)		(151)		(150)
Amortization of:
Prior service costs	—		—		1		—
Actuarial loss	29		31		88		94
Net Periodic Benefit Cost	$	11	$	20	$	34	$	60

The components of net periodic benefit cost for postretirement benefits for the three and nine months ended September 30, 2021 and 2020, respectively, consisted of: 

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
(Millions)
Service cost	$	1	$	1	$	2	$	2
Interest cost	2		4		7		10
Expected return on plan assets	(2)		(2)		(5)		(6)
Amortization of:
Prior service costs	(1)		(3)		(4)		(7)
Actuarial loss	—		—		1		1
Net Periodic Benefit Cost	$	—	$	—	$	1	$	—