Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation - Performance Share Units - Additional Information (Detail)

v3.8.0.1
Stock Based Compensation - Performance Share Units - Additional Information (Detail) - USD ($)
12 Months Ended
Oct. 24, 2016
May 21, 2015
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Performance based equity plan market capitalization minimum amount         $ 100,000,000
Performance based equity plan market capitalization maximum amount         $ 1,100,000,000
Share-based compensation arrangement by share-based payment award, options, grants in period, gross     0 0 0
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period     1,253,085    
Share-based compensation arrangement by share-based payment award, options, vested in period, fair value       $ 106,600,000  
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected dividend rate       0.00%  
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected volatility rate       75.00%  
Share-based compensation arrangement by share-based payment award, fair value assumptions, risk free interest rate       1.04%  
Performance Shares [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement by share-based payment award, options, grants in period, gross     0    
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period     63,908    
Share based compensation arrangement by share based payment award options grants in period fair value     $ 3,218,000    
Share based compensation arrangement by share based payment award unamortized value     $ 819,910    
Share based compensation arrangement by share based payment award unamortized weighted average period     1 year    
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 available for grant     0    
Share-based compensation arrangement by share-based payment award, options, vested in period, fair value     $ 298,857,000    
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected dividend rate     0.00%    
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected volatility rate     75.00%    
Share-based compensation arrangement by share-based payment award, fair value assumptions, risk free interest rate     0.66%    
Allocated share-based compensation expense     $ 1,661,650 $ 2,285,683 $ 489,239
Performance Based Equity Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Performance based equity plan market capitalization minimum amount   $ 100,000,000      
Performance based equity plan market capitalization maximum amount   $ 1,100,000,000      
Percentage of performance share units to be earned on achievement of market capitalization growth   100.00% 100.00%   100.00%
Performance Based Equity Plan [Member] | Performance Share Units [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement by share-based payment award, options, grants in period, gross   639,075      
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 available for grant     31,951    
2013 Equity Incentive Plan [Member] | Performance Share Units [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share based compensation arrangement by share based payment award options grants in period fair value     $ 2,332,000    
2015 Performance Share Unit Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement by share-based payment award, options, grants in period, gross     1,342,061    
2015 Performance Share Unit Plan [Member] | Performance Shares [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement by share-based payment award, options, grants in period, gross     1,278,153    
Mr. Rizzone [Member] | 2013 Equity Incentive Plan [Member] | Performance Share Units [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period 150,000