Consolidated statements of comprehensive loss (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net loss	$ (13,713)	$ (5,840)	$ (34,591)	$ (15,110)
Other comprehensive income (loss)
Unrealized gain (loss) on investments, net of taxes	602	(208)	540	(692)
Unrealized loss on currency translation	(2)		(2)	(1)
Other comprehensive income (loss)	600	(208)	538	(693)
Comprehensive loss	$ (13,113)	$ (6,048)	$ (34,053)	$ (15,803)