Stock-Based Compensation - Summary of Director Awards Activity (Detail) - Board of Directors [Member]	9 Months Ended
	Sep. 30, 2020 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, Beginning balance, Shares | shares	4,831,000
Options Outstanding, Granted | shares	60,998
Shares vested, Shares | shares	(63,413)
Outstanding, Ending balance, Shares | shares	2,416,000
Weighted Average Fair Value, Beginning balance | $ / shares	$ 6.90
Shares awarded, Weighted Average Fair Value | $ / shares	6.59
Shares vested, Weighted Average Fair Value | $ / shares	6.60
Weighted Average Fair Value, Ending balance | $ / shares	$ 6.90