CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - UNAUDITED (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 9,358us-gaap_NetIncomeLoss	$ 9,691us-gaap_NetIncomeLoss
Other comprehensive income, net of tax:
Foreign currency translation adjustments	(9,535)	904
Unrealized holding gains on short-term investments arising during period	3	19
Cash flow hedges:
Unrealized gains on change in fair value of interest rate swap contracts (net of tax effect of $0 and $110)		195
Reclassification adjustment for losses included in net income (net of tax effect of $0, and $(55))		(97)
Net change in cash flow hedges		98
Other comprehensive income (loss), net of tax	(9,532)	1,021
Total comprehensive income (loss), net of tax	$ (174)us-gaap_ComprehensiveIncomeNetOfTax	$ 10,712us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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