Quarterly report pursuant to Section 13 or 15(d)

Notes Payable to Former Stockholders - Additional Information (Detail)

v3.10.0.1
Notes Payable to Former Stockholders - Additional Information (Detail) - USD ($)
$ in Millions
9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Restricted Stock - Notes Payable [Member]    
Debt Instrument [Line Items]    
Unsecured notes interest rate 5.00%  
Unsecured notes maturity date Jun. 30, 2020  
SARs - Notes Payable [Member]    
Debt Instrument [Line Items]    
Unsecured notes interest rate 5.00%  
Unsecured notes maturity date Jun. 30, 2020  
Notes Payable to Former Stockholders [Member]    
Debt Instrument [Line Items]    
Principal and interest payments on notes payable to former stockholders $ 1.5 $ 1.5