Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net income	$ 18,141	$ 11,658	$ 35,819	$ 26,574
Other comprehensive income (loss):
Change in unrecognized pension and post-retirement benefit costs	0	0	0	28
Income tax (provision) benefit on change in unrecognized pension and post-retirement benefit costs	(111)	(18)	(111)	9
Foreign currency translation adjustments	(2,017)	2,540	(287)	(3,718)
Income tax provision on foreign currency translation adjustments	(394)	(410)	(728)	(60)
Other comprehensive income (loss)	(2,522)	2,112	(1,126)	(3,741)
Comprehensive income	15,619	13,770	34,693	22,833
Comprehensive income (loss) attributable to non-controlling interest	14	(140)	74	(677)
Comprehensive income attributable to controlling interest	$ 15,605	$ 13,910	$ 34,619	$ 23,510