Consolidated Statement of Stockholders' Equity (Deficit) (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Stockholders' Equity [Abstract]
Issuance costs of common stock from secondary offering	$ 4,529		$ 3,564
Issuance costs of common stock from conversion of convertible notes			18
Issuance costs of common stock from financing agreement, (in usd per share)			$ 3.86
Issuance of common stock from financing agreement, issuance cost			96
Issuance costs of common stock from July 2012 offering		3,328
Issuance costs of controlled equity offering	$ 371