Organization and Business (Details) (USD $) Share data 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, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Organization and Business [Abstract]
Common stock, issued (in shares)	9,775	8,750	9,800
Common stock public offering price (in dollars per share)		$ 4.60	$ 4.40
Common stock public offering proceeds	$ 40,100,000	$ 37,500,000	$ 40,078,000	$ 23,348,000	$ 0
Funding and Financial Matters [Abstract]
Cash and cash equivalents at end of period			65,860,000	58,838,000	70,105,000	47,918,000
Decrease in cash and cash equivalents			7,022,000	(11,267,000)	22,187,000
Minimum number of years cash will fund operations			1 year
Cash, cash equivalents and auction rate securities			68,068,000	62,078,000
Increase in cash, cash equivalents and auction rate securities			$ 6,000,000