Pension and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2018

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

Pension and other postretirement benefits expenses consisted of the following:

	Three months ended March 31,
Pensions	2018			2017
Service cost	$	1,590		$	1,643
Interest cost	4,309			4,621
Expected return on plan assets	(7,394		)	(6,860		)
Amortization of prior service cost	141			109
Amortization of actuarial losses	2,811			2,480
Settlement gain	—			(261		)
Net periodic benefit cost	$	1,457		$	1,732

	Three months ended March 31,
Other Postretirement Benefits	2018		2017
Service cost	$	24	$	22
Interest cost	344		389
Amortization of prior service cost (credit)	5		(17		)
Amortization of actuarial losses	160		69
Net periodic benefit cost	$	533	$	463