Employee Benefits (Tables)

9 Months Ended

Sep. 30, 2020

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 combined pension plan includes the following components:

	Combined Pension Plan
	Three Months Ended September 30,			Nine Months Ended September 30,
	2020		2019	2020	2019
	(Dollars in millions)
Service cost	$	15	14	44	42
Interest cost	81		109	243	326
Expected return on plan assets	(147)		(155)	(445)	(464)
Recognition of prior service credit	(3)		(2)	(7)	(6)
Recognition of actuarial loss	50		54	152	167
Net periodic pension benefit (income) expense	$	(4)	20	(13)	65

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,
	2020		2019	2020	2019
	(Dollars in millions)
Service cost	$	4	3	11	11
Interest cost	17		27	57	82
Recognition of prior service cost	4		5	12	13
Curtailment loss	7		—	7	—
Net periodic post-retirement benefit expense	$	32	35	87	106