Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Summary of Stock-Based Compensation Granted as Deemed Dividends (Detail)

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Stock-Based Compensation - Summary of Stock-Based Compensation Granted as Deemed Dividends (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Nonemployee Restricted Stock Units [Member] | Cellectis [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Deemed dividends from grants to Cellectis employees $ 1,358 $ 2,253 $ 3,574