CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other comprehensive income (loss):
Currency translation adjustment, tax	$ (194)	$ (219)	$ 77
Reclassification adjustment for gain (loss) of marketable securities included in net earnings, tax	0	0	(37)
Unrealized holding gains (losses) on marketable securities arising during the period, tax	5	90	45
Change in unfunded SERP liability, tax	$ 2	$ (631)	$ 457