Condensed Consolidated Statements of Comprehensive Income (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Condensed Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net income	$ 11,153	$ 10,429	$ 24,403	$ 22,687
Other comprehensive income
Change in unrecognized pension and post-retirement benefit costs	0	0	2	0
Income tax (provision) benefit on change in unrecognized pension and post-retirement benefit costs	(12)	(16)	58	(41)
Foreign currency translation adjustments	(4,523)	(2,638)	(6,816)	(527)
Income tax benefit on foreign currency translation adjustments	684	529	993	118
Other comprehensive income (loss)	(3,851)	(2,125)	(5,763)	(450)
Comprehensive income	7,302	8,304	18,640	22,237
Comprehensive income (loss) attributable to non-controlling interest	(212)	(40)	(257)	3
Comprehensive income attributable to controlling interest	$ 7,514	$ 8,344	$ 18,897	$ 22,234