Summary of Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2021	Dec. 31, 2020
Equity [Abstract]
Beginning Balance		2,398
Granted at fair market value		20
Forfeited, cancelled, or expired		(100)
Ending Balance		2,318	2,398
Options exercisable at June 30, 2021		2,222
Vested options expired during the period ended June 30, 2021		91
Beginning Balance		$ 2.96
Granted at fair market value		1.29
Forfeited, cancelled, or expired		7.87
Ending Balance		2.73	$ 2.96
Options exercisable at June 30, 2021		2.80
Vested options expired during the period ended June 30, 2021		$ 8.48
Weighted-Average Remaining Contractual Term (Years)
Options outstanding		6 years 10 months 24 days	7 years 2 months 12 days
Options exercisable		6 years 10 months 24 days
Options outstanding	[1]	$ 405	$ 53
Options exercisable	[1]	$ 396

[1] The intrinsic value calculation does not include negative values, which can occur when the fair market value on the reporting date is less than the exercise price of the award.