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Description of Business - Additional Information (Detail)
$ in Thousands
12 Months Ended
Dec. 31, 2019
USD ($)
shares
Dec. 31, 2018
USD ($)
shares
Organization Consolidation And Presentation Of Financial Statements [Abstract]    
Place of incorporation Arizona  
Year of incorporation 2002  
Place of reincorporation Delaware  
Date of reincorporation 2015-03  
Reverse split of issued and outstanding common stock 1:20  
Stock split conversion ratio 0.05  
Common stock, authorized | shares 150,000,000 150,000,000
Accumulated deficit $ (207,171) $ (178,366)
Cash and cash equivalents 8,417 11,998
Short-term investments 16,915 9,825
Net losses (28,873) (13,480)
Net cash used in operations $ (17,198) $ (13,631)