CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income	$ 121,485us-gaap_NetIncomeLoss	$ 73,573us-gaap_NetIncomeLoss	$ 68,098us-gaap_NetIncomeLoss
Cash flows hedges [Abstract]
Net unrealized gain (loss), net of tax of $0, $13, and $0 in 2014, 2013, and 2012, respectively	(118)	104	0
Reclassification of net realized (gain) loss into current operations	46	0	0
Net change related to cash flow hedges	(72)	104	0
Net unrealized gain (loss), net of tax of $40, ($147), and $129 in 2014, 2013, and 2012, respectively	579	(190)	2,079
Reclassification of net realized (gain) loss into current operations	(673)	(314)	(1,695)
Net change related to available-for-sale investments	(94)	(504)	384
Currency translation adjustments
Foreign currency translation adjustments, net of tax of ($870), $22, and ($7) in 2014, 2013, and 2012, respectively	(9,400)	82	(12,546)
Other comprehensive income (loss), net of tax	(9,566)	(318)	(12,162)
Total comprehensive income	$ 111,919us-gaap_ComprehensiveIncomeNetOfTax	$ 73,255us-gaap_ComprehensiveIncomeNetOfTax	$ 55,936us-gaap_ComprehensiveIncomeNetOfTax

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