Consolidated Statements of Operations and Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Tax expense (benefit) on changes in value of financial instruments designated as cash flow hedges	$ 671	$ (491)	$ 134	$ 161
Tax on foreign currency translation adjustments	0	0	0	0
Tax (benefit) expense on unrealized gain (loss) on investments	$ (37)	$ 26	$ (8)	$ (11)