Pension and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

Pension and other postretirement benefits expenses consisted of the following:

	Three months ended September 30,						Nine months ended September 30,
Pensions	2018			2017			2018			2017
Service cost	$	1,491		$	1,572		$	4,479		$	4,674
Interest cost	4,336			4,764			13,028			14,051
Expected return on plan assets	(7,615		)	(7,206		)	(22,392		)	(20,882		)
Amortization of prior service cost	141			110			422			330
Amortization of actuarial losses	2,879			2,703			8,719			7,846
Curtailment gain	—			—			—			(7,217		)
Settlement gain	—			298			—			(193		)
Net periodic benefit cost	$	1,232		$	2,241		$	4,256		$	(1,391	)

	Three months ended September 30,					Nine months ended September 30,
Other Postretirement Benefits	2018		2017			2018		2017
Service cost	$	22	$	20		$	64	$	62
Interest cost	338		389			1,019		1,170
Amortization of prior service cost (credit)	5		(17		)	15		(51		)
Amortization of actuarial losses	135		68			421		207
Net periodic benefit cost	$	500	$	460		$	1,519	$	1,388