Interim Financial Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Public Offering [Abstract]
Proceeds				$ 37,459
Public Offering shares issued		8,750,000
Common stock offering price		$ 4.60
Proceeds from future sales of common stock under an agreement with investment bank	$ 50,000		$ 50,000
Funding and Financial Matters [Abstract]
Cash and cash equivalents at end of period	99,309		99,309	85,347
Increase (decrease) in cash and cash equivalents	$ (9,121)		$ (19,993)	$ 19,487
Minimum number of years cash will fund operations (in years)			1 year