Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net income	$ 7,053	$ 9,963	$ 23,343	$ 27,770
Other comprehensive income (loss)
Foreign currency translation adjustment	(367)	(664)	(297)	(271)
Amortization of net actuarial loss included in net periodic cost	622	523	1,245	1,050
Retirement liabilities - before tax	622	523	1,245	1,050
Income tax expense	(246)	(205)	(493)	(410)
Net current period other comprehensive income, Retirement plan items	376	318	752	640
Net current period other comprehensive income	9	(346)	455	369
Comprehensive income	$ 7,062	$ 9,617	$ 23,798	$ 28,139