Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Restricted Stock Units - Additional Information (Detail)

v3.19.1
Stock-Based Compensation - Restricted Stock Units - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized stock-based compensation expense related to to non-vested stock options and restricted stock units $ 9.9    
2017 Omnibus Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock, vesting period 6 years    
Restricted Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total fair value vested $ 2.7 $ 0.3  
Unrecognized stock-based compensation expense, expected recognition weighted-average period 47 months    
Restricted Stock Units [Member] | 2017 Omnibus Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock, vesting period 5 years    
Employee Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized stock-based compensation expense, expected recognition weighted-average period 50 months    
Nonemployee Restricted Stock Units [Member] | Cellectis [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividends $ 2.3 $ 3.6 $ 0.0