Stockholders' Equity (Equity Distribution Agreement) (Details) (Maxim 2012 Agreement [Member], USD $)	0 Months Ended	3 Months Ended	20 Months Ended	0 Months Ended
	Jul. 23, 2012	Mar. 31, 2014	Mar. 31, 2014	Oct. 05, 2012 October 5, 2012 Prospectus Supplement Increased Offering [Member]	Oct. 05, 2012 December 23, 2013 Prospectus Supplement Increased Offering [Member]	Sep. 14, 2012 Minimum [Member] September 14, 2012 Prospectus Supplement Increased Offering [Member]	Sep. 14, 2012 Maximum [Member] September 14, 2012 Prospectus Supplement Increased Offering [Member]
Class of Stock [Line Items]
Maximum dollar amount of shares under the EDA	$ 75,000,000
Fixed commission rate for gross proceeds $10,000,000 or less (percent)	4.00%
Gross proceeds from common stock, threshold	10,000,000
Fixed commission rate for gross proceeds in excess of $10,000,000 (percent)	3.00%
Number of shares to be sold under the equity distribution agreement				40,000,000	90,000,000	12,000,000	20,000,000
Number of shares sold under equity distribution agreement		14,471,585	44,941,739
Cash proceeds from shares sold under equity distribution agreement		6,385,000	29,388,000
Commissions paid on shares sold under equity distribution agreement		$ 197,000	$ 1,025,000