XML 55 R32.htm IDEA: XBRL DOCUMENT v3.7.0.1
Description of Business, Basis of Presentation and Going Concern - Additional Information (Detail) - USD ($)
$ in Thousands, shares in Millions
12 Months Ended
Nov. 21, 2016
Apr. 30, 2017
Apr. 30, 2016
Apr. 30, 2015
Apr. 30, 2014
Organization And Basis Of Presentation [Line Items]          
Percentage of voting interest owned 81.00%        
Accumulated deficit   $ 55,855 $ 37,252    
Cash and cash equivalents   $ 30,950 $ 21,764 $ 2,526 $ 481
Carbylan Therapeutics Inc. [Member]          
Organization And Basis Of Presentation [Line Items]          
Date of share purchase transaction   Nov. 21, 2016      
Percentage of interest owned by equity holders 19.00%        
Common shares issued to stockholders 7.8        
Common shares retained by stockholders 1.9