Employee Retirement Plans (Schedule of Funded Status) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at	$ 1,377	$ 1,685
Interest cost	46	59	$ 66
Actuarial losses (gains)	7	5
Benefits paid	(360)	(372)
Projected benefit obligation at	1,070	1,377	$ 1,685
Fair value of plan assets	0	0
Under funded status	(1,070)	(1,377)
Unamortized prior service cost	2	4
Unrecognized actuarial gain	(173)	(200)
Net amount recognized	$ (1,241)	$ (1,573)