Employee Benefits (Tables)

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Schedule of components of net periodic pension benefit (income) expense and post-retirement benefit expense

Net periodic benefit (income) expense for our qualified and non-qualified pension plans included the following components:

	Pension Plans
	Three Months Ended September 30,					Nine Months Ended September 30,
	2018			2017		2018		2017
	(Dollars in millions)
Service cost	$	17		16		49		47
Interest cost	99			102		296		308
Expected return on plan assets	(171		)	(166	)	(513	)	(499	)
Recognition of prior service credit	(2		)	(2	)	(6	)	(6	)
Recognition of actuarial loss	45			51		135		154
Net periodic pension benefit (income) expense	$	(12	)	1		(39	)	4

Net periodic benefit expense for our post-retirement benefit plans included the following components:

	Post-Retirement Benefit Plans
	Three Months Ended September 30,				Nine Months Ended September 30,
	2018			2017	2018		2017
	(Dollars in millions)
Service cost	$	4		4	13		13
Interest cost	24			25	73		75
Expected return on plan assets	(1		)	—	(1	)	(1	)
Recognition of prior service cost	5			5	15		15
Net periodic post-retirement benefit expense	$	32		34	100		102