Common Stock (Tables)

9 Months Ended

Sep. 30, 2013

Common Stock

Schedule of shares reserved for future issuance

(in thousands)	December 31, 2012	September 30, 2013
Common stock warrants	2,842	2,777
Options to purchase common stock	18,066	20,355
Conversion premium on the Notes	—	25,000
	20,908	48,132