Annual report pursuant to Section 13 and 15(d)

Capital Stock - ATM Agreements - Additional Information (Details)

v3.6.0.2
Capital Stock - ATM Agreements - Additional Information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Class Of Warrant Or Right [Line Items]      
Proceeds from issuance of common stock $ 57,000 $ 481,000 $ 41,442,000
Common Stock [Member]      
Class Of Warrant Or Right [Line Items]      
Sale of shares 13,000   405,000
2015 ATM Agreement [Member]      
Class Of Warrant Or Right [Line Items]      
Sales commission paid per transaction (in hundredths) 3.00%    
Proceeds from issuance of common stock $ 56,000    
Offering costs offset against proceeds upon sale of common stock $ 56,000    
2015 ATM Agreement [Member] | Common Stock [Member]      
Class Of Warrant Or Right [Line Items]      
Sale of shares 10,365 0  
2015 ATM Agreement [Member] | Prepaid Expenses and Other Current Assets [Member]      
Class Of Warrant Or Right [Line Items]      
Capitalized offering costs $ 200,000 $ 100,000