Annual report pursuant to Section 13 and 15(d)

Summary of Treasury Stock Activity (Parenthetical) (Detail)

v3.20.4
Summary of Treasury Stock Activity (Parenthetical) (Detail) - $ / shares
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Schedule of Treasury Stock [Line Items]      
Common stock repurchased value as result of restricted stock forfeitures $ 0.001 $ 0.001 $ 0.001
Minimum      
Schedule of Treasury Stock [Line Items]      
Market Value of Restricted Shares 8.03 8.03 8.03
Maximum      
Schedule of Treasury Stock [Line Items]      
Market Value of Restricted Shares $ 44.44 $ 44.44 $ 44.44