Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2018

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

Net periodic benefit cost (credit) is as follows:

	Pension Benefits
	Three Months Ended   March 31,
	2018			2017
	(Millions)
Components of net periodic benefit cost (credit):
Service cost	$	14		$	13
Interest cost	11			15
Expected return on plan assets	(16		)	(20		)
Amortization of net actuarial loss	6			7
Net periodic benefit cost (credit)	$	15		$	15

	Other Postretirement Benefits
	Three Months Ended   March 31,
	2018			2017
	(Millions)
Components of net periodic benefit cost (credit):
Interest cost	$	2		$	2
Expected return on plan assets	(3		)	(3		)
Amortization of prior service credit	(1		)	(3		)
Reclassification to regulatory liability	1			1
Net periodic benefit cost (credit)	$	(1	)	$	(3	)