Common Stock Offerings (Details Textual) (USD $)	1 Months Ended										12 Months Ended
	Nov. 30, 2012	Jan. 31, 2012	Feb. 28, 2011	Oct. 31, 2010	Sep. 30, 2010	Mar. 31, 2010	Jul. 31, 2009	Nov. 30, 2007	Mar. 31, 2007	Feb. 28, 2006	Dec. 31, 2012	Dec. 31, 2006	Dec. 31, 2004	Feb. 29, 2012	Dec. 31, 2011	Jul. 31, 2010
Proceeds from Issuance of Common Stock		$ 23,700,000	$ 40,300,000	$ 40,300,000	$ 2,900,000	$ 18,200,000	$ 13,300,000	$ 48,900,000	$ 12,500,000			$ 21,500,000	$ 14,500,000
Common stock issued during period, shares		4,989,275	10,062,500	8,214,286	634,500	6,700,000	3,325,000	7,388,172	2,648,306			7,166,666	5,532,994
Stock Authorized Under Shelf Registration		63,950,000	63,950,000	61,566,686			62,218,060							100,000,000
Common Stock, Shares, Available For Issuance																3,000,000
Proceeds From Equity Issuance, Per Share Amount					$ 4.49
Warrants Issued To Purchase Common Stock, Shares						2,345,000			794,492	716,666	1,286,764	2,149,999	483,701
Warrant Fair Value						3,900,000			1,300,000	700,000		1,100,000	14,000
Common stock, par value (in dollars per share)						$ 2.79			$ 5.66	$ 3.30	$ 0.0001	$ 4.20	$ 2.88		$ 0.0001
Payments of Stock Issuance Costs		1,600,000	2,500,000			1,500,000	900,000	3,200,000	1,000,000	1,600,000			1,000,000
Value Of Common Stock Sold, Percentage										110.00%
Warrant, Expiration Period										7 years			7 years
Debt Conversion, Converted Instrument, Amount													1,700,000
Common stock issued in conversion of loan													677,919
Sale Of Shares Aggregate Offering Price Maximum Limit	$ 20,000,000
Volume Weighted Average Closing Bid Price Common Stock									$ 12.00			$ 9.00