STATEMENTS OF COMPREHENSIVE LOSS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
STATEMENTS OF COMPREHENSIVE LOSS [Abstract]
Net loss	$ (13,810)	$ (9,996)
Other comprehensive income (loss):
Net unrealized gains (losses) on investments available-for-sale	(1)	39
Reclassification adjustment for gains included in net loss	(615)
Foreign currency translation adjustment	(133)
Other comprehensive income (loss)	(749)	39
Comprehensive loss	$ (14,559)	$ (9,957)