Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) [Abstract]
Net income (loss)	$ 2,955	$ 6,903	$ 40,535	$ (13,649)
Other comprehensive loss:
Foreign currency translation adjustments	(3,524)	(1,536)	(2,671)	(7,845)
Change in unrecognized pension benefit cost	0	0	0	65
Other comprehensive loss	(3,524)	(1,536)	(2,671)	(7,780)
Comprehensive income (loss)	(569)	5,367	37,864	(21,429)
Comprehensive loss attributable to non-controlling interest	105	122	167	407
Comprehensive income (loss) attributable to controlling interest	$ (464)	$ 5,489	$ 38,031	$ (21,022)