Other Employee Benefit Plans (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net earnings (loss)	$ 1,286	$ 78	$ 500
Prior service cost	(15)	24	161
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	1,271	102	$ 661
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Net loss	(344)	(1,630)
Prior service cost	0	15
Total recognized in AOCI	$ (344)	$ (1,615)