Our qualified and nonqualified defined benefit plans were amended to freeze benefit accruals for all persons entitled to benefits under the plan in 2016. We will continue recording pension expense related to these plans, primarily representing interest costs on the accumulated benefit obligation and amortization of actuarial losses accumulated in the plan, as well as income from expected investment returns on pension assets. Since the plans have been frozen, no service costs are included in net periodic pension expense. The expected long-term rate of return on plan assets is 7.50 percent.

We made a $20.4 million contribution to our qualified defined benefit plan on September 7, 2018. The fair value of the plan was not re-measured for the impact of the contribution. The pension contribution was deducted on our 2017 Consolidated Federal Income Tax Return and we recognized a return to provision discrete tax benefit of $2.9 million due to the decrease in the federal statutory rate of 35 percent to 21 percent resulting from tax legislation in December 2017.

The following table summarizes the components of net periodic pension cost for the periods presented:



	Three Months Ended September 30,								Nine Months Ended September 30,
(dollars in thousands)	2018				2017				2018				2017
Components of Net Periodic Pension Cost
Interest cost on projected benefit obligation		$	978			$	1,025			$	2,912			$	3,075
Expected return on plan assets		(1,566		)		(1,582		)		(4,700		)		(4,746		)
Net amortization		512				475				1,601				1,424
Net Periodic Pension Expense		$	(76	)		$	(82	)		$	(187	)		$	(247	)

The components of net periodic pension expense are included in salaries and employee benefits on the Consolidated Statements of Comprehensive Income.