Interim Financial Statements (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Public Offering [Abstract]
Proceeds		$ 37,459	$ 40,079
Public Offering shares issued		8,750,000
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	85,230	85,230	75,597	65,860	58,838
Increase (decrease) in cash and cash equivalents	$ (117)	$ 19,370	$ 16,759
Minimum number of years cash will fund operations (in years)		1 year