Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net income	$ 11,658	$ 14,490	$ 26,574	$ 24,036
Other comprehensive income
Change in unrecognized pension and post-retirement benefit costs	0	0	28	0
Income tax (provision) benefit on change in unrecognized pension and post-retirement benefit costs	(18)	(1)	9	(16)
Foreign currency translation adjustments	2,540	1,877	(3,718)	2,128
Income tax (provision) benefit on foreign currency translation adjustments	(410)	(1)	(60)	63
Other comprehensive income (loss)	2,112	1,875	(3,741)	2,175
Comprehensive income	13,770	16,365	22,833	26,211
Comprehensive income (loss) attributable to non-controlling interest	(140)	61	(677)	192
Comprehensive income attributable to controlling interest	$ 13,910	$ 16,304	$ 23,510	$ 26,019