CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Research and Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	$ 609	$ 1,247	$ 2,198	$ 3,690
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	345	840	1,255	2,155
Cost of Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		$ 220		$ 220