Condensed Consolidated Statements of Comprehensive Income (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Condensed Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net income	$ 9,547	$ 13,251
Other comprehensive income
Change in unrecognized pension and post-retirement benefit costs	0	(123)
Income tax (provision) benefit on change in unrecognized pension and post-retirement benefit costs	(15)	70
Foreign currency translation adjustments	250	(2,169)
Income tax benefit on foreign currency translation adjustments	64	310
Other comprehensive income (loss)	299	(1,912)
Comprehensive income	9,846	11,339
Comprehensive income (loss) attributable to non-controlling interest	131	(45)
Comprehensive income attributable to controlling interest	$ 9,715	$ 11,384