Quarterly report pursuant to Section 13 or 15(d)

Equity-Based Compensation - Additional Information (Detail)

v3.10.0.1
Equity-Based Compensation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
May 31, 2016
Aug. 31, 2015
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Nov. 02, 2012
Restricted Stock Units                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Compensation expense     $ 832 $ 832 $ 2,433 $ 2,447    
Unrecognized compensation expense related to unvested awards     $ 2,739   $ 2,739   $ 5,140  
Recognition period of unrecognized compensation expense related to unvested awards         1 year 4 months 2 days   2 years 1 month 2 days  
2012 Equity Incentive Plan                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Shares reserved for issuance     690,077   690,077      
Shares reserved for issuance, authorized               1,687,500
Restricted stock units granted 3,791 966,510            
Fair Value per unit $ 13.19 $ 13.23            
Restricted stock units granted description         Twenty-five percent of the RSUs granted vest and settle on each of the first, second, third and fourth anniversaries of the grant date.      
2012 Equity Incentive Plan | Employee                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock units granted 7,582              
Fair Value per unit $ 13.19              
Restricted stock units granted description         Twenty-five percent of the RSUs granted vest and settle on each of the first, second, third and fourth anniversaries of the grant date.      
2012 Equity Incentive Plan | Board of Directors                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock units granted 3,000              
Fair Value per unit $ 13.19              
Restricted stock units granted description         One hundred percent of the RSUs granted vested and settled on the first anniversary of the grant date.      
2012 Equity Incentive Plan | First Anniversary                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 25.00% 25.00%            
2012 Equity Incentive Plan | First Anniversary | Employee                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 25.00%              
2012 Equity Incentive Plan | First Anniversary | Board of Directors                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 100.00%              
2012 Equity Incentive Plan | Second Anniversary                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 25.00% 25.00%            
2012 Equity Incentive Plan | Second Anniversary | Employee                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 25.00%              
2012 Equity Incentive Plan | Third Anniversary                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 25.00% 25.00%            
2012 Equity Incentive Plan | Third Anniversary | Employee                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 25.00%              
2012 Equity Incentive Plan | Fourth Anniversary                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 25.00% 25.00%            
2012 Equity Incentive Plan | Fourth Anniversary | Employee                
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                
Restricted stock, vesting percentage 25.00%