Employee Retirement Plans (Components of Net Periodic Pension and Other Post-Retirement Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost	$ 59	$ 66	$ 88
Amortization of unrecognized prior service cost	6	14	15
Net periodic pension cost	$ 52	$ 80	$ 103
Discount rate	3.81%	3.94%	3.74%