Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation - Equity Incentive Plan - Additional Information (Detail)

v3.8.0.1
Stock Based Compensation - Equity Incentive Plan - Additional Information (Detail) - USD ($)
12 Months Ended
Apr. 10, 2015
Mar. 27, 2014
Mar. 10, 2014
Dec. 31, 2017
Dec. 31, 2016
Dec. 28, 2017
May 19, 2016
Mar. 06, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Employee contribution through payroll withholdings       $ 869,066 $ 727,784        
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period       1,253,085          
Performance Share Units [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share-based compensation arrangement by share-based payment award, number of shares authorized 1,310,104                
Share-based compensation arrangement by share-based payment award, number of shares available for grant       0          
Employee Stock Purchase Plan [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Common stock, capital shares reserved for future issuance 600,000                
Share-based compensation arrangement by share-based payment award, number of shares available for grant       405,921          
Lowest percentage of annual compensation to be utilized by an employee for the plan 1.00%                
Highest percentage of annual compensation to be utilized by an employee for the plan 10.00%                
Maximum number of shares permitted to purchase 7,500                
Offering period 6 months                
Exercise price discount from fair value on offering date 85.00%                
Exercise price discount from fair value on exercise date 85.00%                
Share-based compensation arrangement by share-based payment award, terms of award       On April 10, 2015, the Company’s board of directors approved the ESPP, under which 600,000 shares of common stock have been reserved for purchase by the Company’s employees, subject to approval by the stockholders. On May 21, 2015, the Company’s stockholders approved the ESPP. Employees may designate an amount not less than 1% but not more than 10% of their annual compensation, but for not more than 7,500 shares during an offering period. An offering period shall be six months in duration commencing on or about January 1 and July 1 of each year. The exercise price of the option will be the lesser of 85% of the fair market of the common stock on the first business day of the offering period and 85% of the fair market value of the common stock on the applicable exercise date.          
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period       64,542 85,356        
2013 Equity Incentive Plan [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share-based compensation arrangement by share-based payment award, number of shares authorized                 1,042,167
Percentage of total number of shares to be issued under incentive plan     18.00%            
Share-based compensation arrangement by share-based payment award, other share increase (decrease)   2,335,967              
Common stock to be issued       829,515          
2013 Equity Incentive Plan [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share-based compensation arrangement by share-based payment award, number of shares authorized             4,485,967    
Common stock, capital shares reserved for future issuance             2,150,000    
Share-based compensation arrangement by share-based payment award, number of shares available for grant       31,951          
Non-Employee Equity Compensation Plan 2014 [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share-based compensation arrangement by share-based payment award, number of shares authorized             600,000 250,000  
Common stock, capital shares reserved for future issuance             350,000    
Common stock available to be issued       292,655          
2017 Equity Inducement Plan [Member] | Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Common stock, capital shares reserved for future issuance           600,000