Condensed Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Condensed Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 11,806	$ 11,494
Other comprehensive income, net of tax:
Unrealized pension plan gains and prior service costs	(9)	4
Cash flow hedges:
Unrealized loss on change in fair value of interest rate swap contracts, net of $93 tax	(153)
Less: Reclassification adjustment for losses included in net income, net of $(2) tax	(2)
Unrealized loss on change in fair value of interest rate swap contracts, Total	(151)
Foreign currency translation adjustments	3,291	5,908
Other comprehesive income, net of tax	3,131	5,912
Total comprehensive income	$ 14,937	$ 17,406