Postretirement Benefit Obligations (Tables)

9 Months Ended

Sep. 30, 2018

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

The components of net periodic benefit cost of the Company’s pension plan are as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Service costs	$	2,001	$	1,908	$	6,004	$	5,724
Interest costs	469		333		1,407		999
Expected return on plan assets	(287)		(76)		(862)		(228)
Net periodic benefit cost	$	2,183	$	2,165	$	6,549	$	6,495