Organization and Business (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2013	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Organization and Business [Abstract]
Common stock, issued (in shares)	9,775	8,750	8,750	9,775
Common stock public offering price (in dollars per share)			$ 4.60	$ 4.40
Common stock public offering proceeds	$ 40,078	$ 37,459	$ 37,459	$ 40,078	$ 23,348
Funding and Financial Matters [Abstract]
Cash and cash equivalents at end of period			119,302	65,860	58,838	70,105
Decrease in cash and cash equivalents			53,442	7,022	(11,267)
Minimum number of years cash will fund operations			1 year
Proceeds from future sales of common stock under an agreement with investment bank			$ 50,000