Condensed Consolidated Statements of Comprehensive Income - Unaudited (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Comprehensive Income Net Of Tax [Abstract]
Net income	$ 14,898	$ 11,806
Other comprehensive income, net of tax:
Foreign currency translation adjustments	(8,788)	3,291
Unrealized holding losses on short-term investments arising during period	(1)
Defined Benefit Pension Plan:
Net loss arising from period (net of tax effect of $(119) and $0)	(183)
Amortization of actuarial loss included in net periodic pension cost (net of tax effect of $28 and $9)	43	(9)
Partial settlement of pension plan liability (net of tax effect of $336 and $0)	546
Net change in defined benefit pension plan	406	(9)
Cash flow hedges:
Unrealized gains (losses) on change in fair value of interest rate swap contracts (net of tax effect of $67 and ($94))	210	(153)
Reclassification adjustment for gains (losses) included in other income (expense) (net of tax effect of $66 and ($2))	104	(2)
Net change in cash flow hedges	106	(151)
Other comprehensive income, net of tax	(8,277)	3,131
Total comprehensive income	$ 6,621	$ 14,937