Employee Benefits (Tables)

9 Months Ended

Sep. 30, 2017

Retirement Benefits [Abstract]

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

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

	Pension Plans
	Three Months Ended September 30,					Nine Months Ended September 30,
	2017			2016		2017		2016
	(Dollars in millions)
Service cost	$	16		16		47		48
Interest cost	102			107		308		321
Expected return on plan assets	(166		)	(183	)	(499	)	(550	)
Recognition of prior service credit	(2		)	(2	)	(6	)	(6	)
Recognition of actuarial loss	51			44		154		131
Net periodic pension benefit expense (income)	$	1		(18	)	4		(56	)

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,
	2017		2016		2017		2016
	(Dollars in millions)
Service cost	$	4	4		13		14
Interest cost	25		29		75		84
Expected return on plan assets	—		(2	)	(1	)	(6	)
Recognition of prior service cost	5		5		15		15
Net periodic post-retirement benefit expense	$	34	36		102		107