Business (Details) (USD $)	0 Months Ended		1 Months Ended
	Jan. 14, 2014	Jul. 23, 2014	Jul. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Capitalization, Equity [Line Items]
Accumulated deficit				$ 486,614,000	$ 465,301,000
Cash and cash equivalents				48,555,000	8,629,000	3,405,000
Reverse stock split ratio	0.02
Underwriting Agreement [Member]
Schedule of Capitalization, Equity [Line Items]
Proceeds from common stock offering, net of issuance costs		$ 53,100,000	$ 53,100,000