CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - UNAUDITED (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net income	$ 9,403	$ 12,072	$ 19,094	$ 26,970
Other comprehensive income, net of tax:
Foreign currency translation adjustments	3,171	(901)	4,075	(9,689)
Unrealized holding gains (losses) on short-term investments arising during period	(9)	(55)	10	(56)
Defined benefit pension plan:
Net loss arising from period (net of tax effect of $0, $0, $0, and $(119))				(183)
Amortization of net actuarial loss included in net periodic pension cost (net of tax effect of $0, $0, $0, and $28)				43
Partial settlement of pension plan liability (net of tax effect of $0, $0, $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 $0, $217, $110, and $350)		342	195	552
Reclassification adjustment for losses included in net income (net of tax effect of $0, $(113), $(55), and $(179))		(178)	(97)	(282)
Net change in cash flow hedges		164	98	270
Other comprehensive income (loss), net of tax	3,162	(792)	4,183	(9,069)
Total comprehensive income, net of tax	$ 12,565	$ 11,280	$ 23,277	$ 17,901