Pension and Other Post Retirement Benefit Plans - Schedule of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Service cost	$ 10	$ 9	$ 55
Interest cost	3,353	3,273	3,087
Expected return on plan assets	(4,778)	(4,508)	(4,471)
Amortization of prior service costs	90	79	64
Amortization of net loss	1,218	1,656	1,722
Settlement loss recognized	761
Net periodic pension cost	$ 654	$ 509	$ 457