Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 8,499	$ 41,317	$ 17,212	$ 94,408
Other comprehensive income, net of tax:
Foreign currency translation adjustment during the period	(876)	302	(957)	(697)
Change in fair value of corporate debt securities
Unrealized holding losses on corporate debt securities arising during the period				(98)
Less: Reclassification adjustments for gains included in net income				(1,296)
Change in fair value of corporate debt securities, net				(1,394)
Other comprehensive income (loss)	(876)	302	(957)	(2,091)
Comprehensive Income	$ 7,623	$ 41,619	$ 16,255	$ 92,317