Employee Benefit Plans - Schedule of Net Periodic Benefit Cost Not Yet Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Retirement Benefits, Description [Abstract]
Unamortized net actuarial loss	$ (186)	$ (156)	$ (186)
Deferred tax benefit at 21% (for March 31, 2018 and December 31, 2017) and 35% (for March 31, 2017)	39	54	39
Net unrecognized postretirement benefits included in accumulated other comprehensive income (loss)	$ (147)	$ (102)	$ (147)
Deferred tax benefit, percentage	21.00%	35.00%	21.00%