Annual report pursuant to Section 13 and 15(d)

Property and Equipment - Additional Information (Detail)

v3.6.0.2
Property and Equipment - Additional Information (Detail) - USD ($)
1 Months Ended 12 Months Ended
Sep. 30, 2016
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Property, Plant and Equipment [Line Items]        
Depreciation   $ 400,000 $ 26,000 $ 23,000
National Holdings Corporation [Member]        
Property, Plant and Equipment [Line Items]        
Depreciation $ 36,000