Annual report pursuant to Section 13 and 15(d)

Cash Proceeds Along with Fair Value Disclosures Related to Grants, Exercises, and Vesting Options (Detail)

v3.21.1
Cash Proceeds Along with Fair Value Disclosures Related to Grants, Exercises, and Vesting Options (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]      
Proceeds from stock options exercised   $ 4 $ 2
Weighted-average fair value of options granted per share $ 0.29 $ 1.51 $ 1.38
Total fair value of shares vested during the year $ 227 $ 587 $ 1,191