Annual report pursuant to Section 13 and 15(d)

Employee Benefits - Additional Information (Detail)

v3.20.1
Employee Benefits - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Postemployment Benefits [Abstract]      
Defined contribution plan, Employees voluntary contributions, Amount $ 192,000 $ 239,000 $ 217,000
Eligibility criteria for employees to participate in the plan Employees are eligible to participate in the plan beginning on the first day of employment.