Employee Benefits

3 Months Ended

Mar. 31, 2018

Retirement Benefits [Abstract]

Employee Benefits

EMPLOYEE BENEFITS

Net Periodic Benefit Cost

The components of the net periodic benefit cost for our pension and postretirement benefit plans are as follows:

	Pension Plan						Postretirement Benefit Plan
Three Months Ended March 31,	2018			2017			2018			2017
Net periodic benefit cost
Service cost	$	2,175		$	1,714		$	749		$	505
Interest cost	1,875			1,765			502			482
Expected return on plan assets	(2,625		)	(2,412		)	—			—
Amortization of prior service credit	—			—			(1,352		)	(1,352		)
Amortization of net loss	1,071			890			589			461
Net periodic benefit cost	$	2,496		$	1,957		$	488		$	96

Employer Contributions

We previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2017 that we expected to contribute $6,400 to the pension plan in 2018. For the three-month period ended March 31, 2018, we contributed $1,600 to the pension plan.