Annual report pursuant to Section 13 and 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.20.1
Organization and Description of Business - Additional Information (Detail) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 12 Months Ended
Feb. 11, 2019
Nov. 14, 2018
Sep. 09, 2016
Dec. 31, 2018
Organization And Nature Of Business [Line Items]        
Sale of Stock, Transaction Date Feb. 11, 2019 Nov. 14, 2018    
Sale of Stock, Number of Shares Issued in Transaction 4.0      
National Holdings Corporation [Member]        
Organization And Nature Of Business [Line Items]        
Merger Agreement Minimum Percentage Of Shares In Tender Offer To Completed Merger     56.60%  
Business Acquisition, Share Price     $ 3.25  
Sale of Stock, Percentage of Ownership before Transaction   56.10%    
Sale of Stock, Price Per Share   $ 3.25    
Sale of Stock, Consideration Received on Transaction   $ 22.9    
Sale of Stock, Consideration Received Per Transaction $ 13.1 $ 9.8    
Sale of Stock, Number of Shares Issued in Transaction 4.0 3.0    
Sale of Stock, Percentage of Ownership after Transaction       32.10%
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares     7.0  
Business Combination, Consideration Transferred     $ 22.9