Consolidated statements of comprehensive loss (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (10,894)	$ (3,376)
Other comprehensive loss:
Unrealized loss on investments, net of tax	(156)	(603)
Unrealized loss on currency translation	1	(1)
Other comprehensive loss	(155)	(604)
Comprehensive loss	$ (11,049)	$ (3,980)