Accumulated Other Comprehensive Loss Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Beginning of period	$ 24,424
End of period	21,633	$ 24,424
AOCI Attributable to Parent [Member]
Beginning of period	(2,437)	(1,594)
Change during the year	616	(843)
End of period	(1,821)	(2,437)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Beginning of period	(2)	(12)
Change during the year	(1)	10
End of period	(3)	(2)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Beginning of period	(2,435)	(1,582)
Change during the year	617	(853)
End of period	$ (1,818)	$ (2,435)