Stockholders' Equity - Summary of Non-Vested Stock Options (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Nonvested at beginning of period (in shares)	3,873,247
Nonvested, shares, granted (in shares)	3,525,512
Nonvested, shares, vested (in shares)	(2,892,808)
Nonvested, shares, forfeited (in shares)	(460,751)
Nonvested at end of period (in shares)	4,045,200
Weighted average grant date fair value, nonvested at December 31, 2018 (in usd per share) | $ / shares	$ 4.45
Nonvested at December 31, 2018, aggregate intrinsic value | $	$ 1,261