Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2020

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

Net periodic benefit cost (credit) is as follows:

	Pension Benefits
	Three Months Ended  June 30,						Six Months Ended  June 30,
	2020			2019			2020			2019
	(Millions)
Components of net periodic benefit cost (credit):
Service cost	$	7		$	11		$	15		$	22
Interest cost	9			13			19			25
Expected return on plan assets	(14		)	(16		)	(27		)	(31		)
Amortization of net actuarial loss	7			4			11			8
Net actuarial loss from settlements	2			—			8			—
Net periodic benefit cost (credit)	$	11		$	12		$	26		$	24

	Other Postretirement Benefits
	Three Months Ended  June 30,						Six Months Ended  June 30,
	2020			2019			2020			2019
	(Millions)
Components of net periodic benefit cost (credit):
Interest cost	$	1		$	2		$	3		$	4
Expected return on plan assets	(2		)	(3		)	(5		)	(5		)
Reclassification to regulatory liability	—			1			1			1
Net periodic benefit cost (credit)	$	(1	)	$	—		$	(1	)	$	—