CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Net income	$ 31,966	$ 34,206	$ 39,214
Other comprehensive loss:
Change in unrecognized pension and post-retirement benefit costs	(178)	(1,820)	2,742
Tax (expense) benefit on change in unrecognized pension and post-retirement benefit costs	36	699	(974)
Foreign currency translation adjustments	(13,848)	(7,670)	(8,821)
Tax benefit on foreign currency translation adjustments	3,341	770	1,657
Other comprehensive loss	(10,649)	(8,021)	(5,396)
Comprehensive loss attributable to non-controlling interest	(1,603)	(565)	(236)
Comprehensive income attributable to controlling interest	$ 22,920	$ 26,750	$ 34,054