Stock Offering (Details Textual) (USD $)	1 Months Ended	3 Months Ended
	Apr. 30, 2011	Mar. 31, 2012
Stock Offering (Textual) [Abstract]
Sale of common stock shares	$ 125,000,000
Number of shares sold under sales agreement		572,510
Net proceeds on sale of common stock		$ 10,300,000