We sponsor a non-contributory defined benefit pension plan for certain union employees. The plan is funded in accordance with the funding requirements of the Employee Retirement Income Security Act of 1974.

We also sponsor a postretirement health care plan for office employees retired before January 1, 1990. The plan allowed retirees who attained the age of 65 to elect the type of coverage desired.

We present service cost within cost of sales and selling and administrative expenses depending on where the relevant employees compensation costs are recorded, and we present other components of net periodic benefit cost (gain) within other expense, net on the Condensed Consolidated Statements of Income.

Retirement and health care plan expense is based on valuations performed by plan actuaries as of the beginning of each fiscal year. The components of the expense consisted of the following:

	Three Months Ended March 31,
(table only in thousands)	2019			2018
Pension plan:
Service cost	$	—		$	97
Interest cost		326			298
Expected return on plan assets		(313	)		(476	)
Amortization of net actuarial loss		65			59
Net periodic benefit cost (gain)	$	78		$	(22	)
Health care plan:
Interest cost	$	1		$	1
Amortization of loss		2			2
Net periodic benefit cost	$	3		$	3

We made contributions to our defined benefit plans during the three-months ended March 31, 2019 and 2018 totaling $0.1 million and $0.2 million, respectively. We anticipate $0.4 million and $24,000 of further contributions to fund the pension plan and the retiree health care plan, respectively, during the remainder of 2019. The unfunded liability of the plans of $8.8 million as of March 31, 2019 and December 31, 2018 is included in Other liabilities on our Condensed Consolidated Balance Sheets.