Employee Benefits

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



	Pension Plans
	Three Months Ended June 30,					Six Months Ended June 30,
	2018			2017		2018		2017
	(Dollars in millions)
Service cost	$	16		14		32		31
Interest cost	98			105		197		206
Expected return on plan assets	(171		)	(167	)	(342	)	(333	)
Recognition of prior service credit	(2		)	(2	)	(4	)	(4	)
Recognition of actuarial loss	46			52		90		103
Net periodic pension benefit (income) expense	$	(13	)	2		(27	)	3

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



	Post-Retirement Benefit Plans
	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018	2017
	(Dollars in millions)
Service cost	$	5	5		9	9
Interest cost	25		25		49	50
Expected return on plan assets	—		(1	)	—	(1	)
Recognition of prior service cost	5		5		10	10
Net periodic post-retirement benefit expense	$	35	34		68	68

Benefits paid by our qualified pension plan are paid through a trust that holds all plan assets. Based on current laws and circumstances, we do not expect any contributions to be required for our qualified pension plan during the remainder of 2018. However, we made a voluntary contribution of $100 million to the trust for our qualified pension plan in June 2018, and made an additional voluntary contribution of $400 million during the third quarter of 2018.