Condensed Consolidated Statements of Comprehensive Income - Unaudited (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income	$ 15,300	$ 9,413	$ 42,270	$ 33,089
Other comprehensive income:
Foreign currency translation adjustments	6,359	6,091	(3,330)	4,609
Unrealized holding gains on short-term investments arising during period	81	2	25	2
Defined benefit pension plan:
Net loss arising from period (net of tax effect of $0, $0, $(119), and $0)			(183)
Amortization of prior service cost included in net periodic pension cost (net of tax effect of $0, $0, $28, and $0)			43	(9)
Partial settlement of pension plan liability (net of tax effect of $0, $0, $336, and $0)			546
Net change in defined benefit pension plan			406	(9)
Cash flow hedges:
Unrealized gains on change in fair value of interest rate swap contracts (net of tax effect of $199, $37, $549, and $27)	313	58	865	42
Reclassification adjustment for losses included in other income (expense) (net of tax effect of $(101), $(49), $(280), and $(101))	(160)	(78)	(442)	(160)
Net change in cash flow hedges	153	(20)	423	(118)
Other comprehensive income, net of tax	6,593	6,073	(2,476)	4,484
Total comprehensive income	$ 21,893	$ 15,486	$ 39,794	$ 37,573