Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 31

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.30(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Subsequent Events (Details) (USD $)	9 Months Ended
Subsequent Events (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Subsequent Event [Line Items]
Net proceeds from the issuance of common shares	$ 24,100,000
Common stock, shares outstanding (in shares)	30,608,392	30,607,916
Current assets:
Cash and cash equivalents	6,036,220	14,344,088	12,453,637	17,988,590
Short-term investments	17,000,000	24,000,000
Prepaid and other current assets	875,093	1,212,041
Total current assets	23,991,724	39,692,448
Total assets	24,467,010	40,231,776
LIABILITIES AND STOCKHOLDERS' EQUITY
Total current liabilities	13,325,029	10,065,935
Stockholders' equity
Common stock	30,609	30,608
Additional paid-in capital	262,656,237	261,318,638
Treasury stock	(2,373,442)	(2,279,238)
Accumulated deficit	(249,171,423)	(228,904,167)
Total stockholders' equity	11,141,981	30,165,841
Total liabilities and stockholders' equity	24,467,010	40,231,776
Actual [Member]
Current assets:
Cash and cash equivalents	6,036,220
Short-term investments	17,000,000
Prepaid and other current assets	955,504
Total current assets	23,991,724
Non-current assets	475,286
Total assets	24,467,010
LIABILITIES AND STOCKHOLDERS' EQUITY
Total current liabilities	13,325,029
Stockholders' equity
Common stock	30,609
Additional paid-in capital	262,656,237
Treasury stock	(2,373,442)
Accumulated deficit	(249,171,423)
Total stockholders' equity	11,141,981
Total liabilities and stockholders' equity	24,467,010
Adjustment [Member]
Current assets:
Cash and cash equivalents	24,100,000
Short-term investments	0
Prepaid and other current assets	0
Total current assets	24,100,000
Non-current assets	0
Total assets	24,100,000
LIABILITIES AND STOCKHOLDERS' EQUITY
Total current liabilities	0
Stockholders' equity
Common stock	11,500
Additional paid-in capital	24,088,500
Treasury stock	0
Accumulated deficit	0
Total stockholders' equity	24,100,000
Total liabilities and stockholders' equity	24,100,000
Pro Forma [Member]
Current assets:
Cash and cash equivalents	30,136,220
Short-term investments	17,000,000
Prepaid and other current assets	955,504
Total current assets	48,091,724
Non-current assets	475,286
Total assets	48,567,010
LIABILITIES AND STOCKHOLDERS' EQUITY
Total current liabilities	13,325,029
Stockholders' equity
Common stock	42,109
Additional paid-in capital	286,744,737
Treasury stock	(2,373,442)
Accumulated deficit	(249,171,423)
Total stockholders' equity	35,241,981
Total liabilities and stockholders' equity	48,567,010
Subsequent Event [Member]
Subsequent Event [Line Items]
Stock issued, underwritten public offering, value	25,900,000
Stock issued underwritten public offering (in shares)	11,500,000
Share price (in dollars per share)	$ 2.25
Net proceeds from the issuance of common shares	$ 24,100,000
Common stock, shares outstanding (in shares)	42,100,000