STATEMENTS OF COMPREHENSIVE LOSS (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
STATEMENTS OF COMPREHENSIVE LOSS [Abstract]
Net loss	$ (15,300)	$ (7,217)	$ (37,929)	$ (20,472)
Other comprehensive income (loss):
Net unrealized gains (losses) on investments available-for-sale	(33)	96	174	204
Foreign currency adjustment	509		509
Other comprehensive income (loss)	476	96	683	204
Comprehensive loss	$ (14,824)	$ (7,121)	$ (37,246)	$ (20,268)