Employee Benefits (Tables)

9 Months Ended

Sep. 30, 2019

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 combined pension plan includes the following components:

	Combined Pension Plan
	Three Months Ended September 30,					Nine Months Ended September 30,
	2019			2018		2019		2018
	(Dollars in millions)
Service cost	$	14		17		42		50
Interest cost	109			99		326		295
Expected return on plan assets	(155		)	(171	)	(464	)	(513	)
Recognition of prior service credit	(2		)	(2	)	(6	)	(6	)
Recognition of actuarial loss	54			45		167		134
Net periodic pension benefit expense (income)	$	20		(12	)	65		(40	)

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

	Post-Retirement Benefit Plans
	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019	2018
	(Dollars in millions)
Service cost	$	3	4		11	13
Interest cost	27		24		82	73
Expected return on assets	—		(1	)	—	(1	)
Recognition of prior service cost	5		5		13	15
Net periodic post-retirement benefit expense	$	35	32		106	100