PENSION AND OTHER POSTRETIREMENT BENEFITS

We have a noncontributory defined benefit pension plan covering substantially all employees first hired prior to July 1, 2015 after the completion of one year of service and 1,000 hours of service. The plan provides retirement benefits based on an employee’s average earnings and years of service. These employees become 100% vested after three years of service, regardless of age. A supplemental benefit plan provides nonqualified benefits for compensation in excess of the IRS compensation limits applicable to the plan and otherwise eligible compensation deferred.

Our plan funding policy is to make contributions, provided that the total annual contributions will not be less than ERISA and the Pension Protection Act of 2006 minimums or greater than the maximum tax-deductible amount, to review the contribution and funding strategy on a regular basis, and to allow discretionary contributions to be made by us from time to time. The assets of the defined benefit pension plan are invested primarily in fixed income investments and equity securities. We pay nonqualified pension benefits when they are due according to the terms of the supplemental benefit plan.

We provide certain postretirement healthcare and life insurance benefits to retired employees. Substantially all of our employees hired or rehired prior to 2014 may become eligible for postretirement medical benefits if they reach the age and service requirements of the retiree medical plan and retire on a pension (except a deferred pension) under the defined benefit pension plan. Medical benefits are self-insured and claims are administered through a third party administrator. The cost of coverage is determined based on the annual projected plan costs. The participant's premium or cost is determined based on Company guidelines. Postretirement life insurance benefits are insured through an insurance company. We fund postretirement benefits as incurred, and accordingly, there were no assets held in the postretirement benefits plan at March 31, 2018 and December 31, 2017.

The net periodic benefit cost for the three months ended March 31, 2018 and 2017 includes the following components:



	Pension Benefits						Postretirement Benefits
	Three Months Ended March 31,						Three Months Ended March 31,

Components of Net Periodic Benefit Cost	2018			2017			2018			2017
Selling, general, and administrative expenses:
Service cost	$	7,100		$	6,700		$	575		$	575
Non-operating expenses:
Interest cost	6,975			7,000			650			700
Expected return on plan assets	(8,075		)	(7,725		)	—			—
Amortization of:
Net actuarial loss	6,725			5,300			225			225
Prior service cost (gain)	75			100			(500		)	(550		)
Net periodic benefit cost	$	12,800		$	11,375		$	950		$	950

We made qualified and nonqualified pension contributions totaling $11,621 and $19,584 during the three-month periods ended March 31, 2018 and 2017, respectively. Additional contributions totaling $30,005 are expected to be paid during the remainder of 2018.