Consolidated statements of comprehensive loss (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (5,894)	$ (1,312)	$ (9,270)	$ (4,679)
Other comprehensive income (loss):
Unrealized gain (loss) on investments, net of tax	120		(483)	42
Unrealized loss on currency translation	(1)	(1)	(2)	(4)
Other comprehensive income (loss)	119	(1)	(485)	38
Comprehensive loss	$ (5,775)	$ (1,313)	$ (9,755)	$ (4,641)