Stock-Based Compensation - (Stock Option) - Additional Information (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) installment $ / shares	Sep. 30, 2019 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation option awards contractual term	10 years
Vesting period for subsequent stock options granted to employees and new directors	4 years
Portion of initial stock options granted to employees and new directors that vests on first anniversary of grant date	25.00%
Portion of initial stock options granted to employees and new directors that vests ratably over three years after completion of first year of service	75.00%
Number of vesting equal installments | installment	36
Options granted, weighted average fair value per share (in dollars per share) | $ / shares	$ 5.53	$ 10.34
Proceeds from exercise of employee stock options	$ 4,202	$ 4,148
Service option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Full acceleration of vesting, employee or executive officer subject to involuntary termination, period post change of control of the Company	24 months
Unrecognized compensation expenses	$ 7,900
Unrecognized compensation expenses, weighted average period	1 year 4 months 24 days