CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - UNAUDITED (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net income	$ 9,691	$ 14,898
Other comprehensive income, net of tax:
Foreign currency translation adjustments	904	(8,788)
Unrealized holding gains (losses) on short-term investments arising during period	19	(1)
Defined benefit pension plan:
Net loss arising from period (net of tax effect of $0 and $(119))		(183)
Amortization of net actuarial loss included in net periodic pension cost (net of tax effect of $0 and $28)		43
Partial settlement of pension plan liability (net of tax effect of $0 and $336)		546
Net change in defined benefit pension plan		406
Cash flow hedges:
Unrealized gains on change in fair value of interest rate swap contracts (net of tax effect of $110 and $133)	195	210
Reclassification adjustment for losses included in net income (net of tax effect of $(55) and $(66))	(97)	(104)
Net change in cash flow hedges	98	106
Other comprehensive income (loss), net of tax	1,021	(8,277)
Total comprehensive income, net of tax	$ 10,712	$ 6,621