Stockholders' Equity (Secondary Public Offerings) (Details) (USD $)	1 Months Ended					1 Months Ended					1 Months Ended	12 Months Ended		1 Months Ended
	May 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Nov. 30, 2010 Secondary Public Offering [Member]	Oct. 31, 2009 Secondary Public Offering [Member]	May 31, 2008 Secondary Public Offering [Member]	Sep. 30, 2012 Secondary Public Offering [Member] Aegis Capital Corp. [Member]	Sep. 19, 2012 Secondary Public Offering [Member] Aegis Capital Corp. [Member]	Feb. 28, 2011 At The Market Equity Offering Sales Agreement [Member]	Dec. 31, 2013 At The Market Equity Offering Sales Agreement [Member]	Jan. 31, 2012 At The Market Equity Offering Sales Agreement [Member]	Dec. 31, 2011 Shelf Registration Statement [Member]	Dec. 31, 2013 Shelf Registration Statement [Member]
Equity Offering [Line Items]
Secondary public offering, shares (in shares)	2,500,000	2,500,000				5,250,000	4,615,385	4,370,000	9,166,700		386,050	1,972,181
New shares issued due to underwriter exercise of over-allotment								570,000
Share price (in dollars per share)						$ 4.15	$ 6.50	$ 14.00		$ 1.20
Proceeds from issuance of common stock	$ 1,400,000	$ 1,425,000				$ 20,400,000	$ 27,900,000	$ 56,800,000	$ 10,200,000		$ 315,270	$ 1,900,000
Issuance of common stock to service provider, shares			240,000
Proceeds from issuance or sale of equity														25,000,000
Unused shelf registration															2,000,000
Potential proceeds from additional shares issued													5,000,000
Percent of share sales payable for compensation													3.00%
Common stock, par value (in dollars per share)				$ 0.0001	$ 0.0001					$ 0.0001
Underwriting discount and offering expenses									$ 837,000
Common stock, shares outstanding (in shares)				61,748,524	51,143,906