Stockholders' Equity (Equity Distribution Agreement) (Details) - Maxim 2012 Agreement [Member] - USD ($)						6 Months Ended
	Mar. 06, 2015	Dec. 23, 2013	Oct. 05, 2012	Sep. 14, 2012	Jul. 23, 2012	Jun. 30, 2015
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 sold under equity distribution agreement						38,919,883
Cash proceeds from shares sold under equity distribution agreement						$ 9,293,000
Commissions paid on shares sold under equity distribution agreement						$ 287,000
October 5, 2012 Prospectus Supplement Increased Offering [Member]
Class of Stock [Line Items]
Number of shares to be sold under the equity distribution agreement			40,000,000
December 23, 2013 Prospectus Supplement Increased Offering [Member]
Class of Stock [Line Items]
Number of shares to be sold under the equity distribution agreement		90,000,000
March 6, 2015 Prospectus Supplement Increased Offering [Member]
Class of Stock [Line Items]
Number of shares to be sold under the equity distribution agreement	117,600,000
Minimum [Member] | September 14, 2012 Prospectus Supplement Increased Offering [Member]
Class of Stock [Line Items]
Number of shares to be sold under the equity distribution agreement				12,000,000
Maximum [Member] | September 14, 2012 Prospectus Supplement Increased Offering [Member]
Class of Stock [Line Items]
Number of shares to be sold under the equity distribution agreement				20,000,000