Stockholders' Equity, Registered Public Offerings (Details) (Registered Public Offerings [Member], Common Stock [Member], USD $)	0 Months Ended						1 Months Ended
	Nov. 08, 2013	Nov. 05, 2013	May 28, 2013	May 10, 2013	Apr. 30, 2012	Mar. 21, 2012	Dec. 05, 2013	Jun. 10, 2013	Apr. 30, 2012
Registered Public Offerings [Member] | Common Stock [Member]
Stockholders' Equity [Line Items]
Issuance of common stock, financing (in shares)		25,000,000		9,500,000		16,071,429
Issue price of common unit (in dollars per unit)	$ 2.00	$ 2.00	$ 1.50	$ 1.50	$ 2.80	$ 2.80			$ 2.80
Gross proceeds	$ 7,500,000	$ 50,000,000	$ 2,000,000	$ 14,300,000		$ 45,000,000
Net proceeds from issuance of common stock	$ 7,100,000	$ 46,800,000	$ 1,900,000	$ 13,200,000		$ 42,100,000
Number of days option granted to underwriters							30 days	30 days	30 days
Number of shares covered under options granted to underwriter (in shares)							3,750,000	1,425,000	2,410,714
Number of shares exercised by the underwriter	3,750,000		1,347,000		0