Activity with Respect to Options Granted (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Shares
Beginning balance, shares	5,042,325
Granted, shares	606,900
Exercised, shares	(500)
Expired, shares	(476,087)
Ending balance, shares	5,172,638	5,042,325
Nonvested, shares	944,433	439,194
Exercisable, shares	4,228,205
Weighted Average Exercise Price
Beginning Balance, Weighted Average Exercise Price	$ 82.42
Granted, Weighted Average Exercise Price	9.96
Exercised, Weighted Average Exercise Price	3.75
Expired, Weighted Average Exercise Price	92.81
Ending Balance, Weighted Average Exercise Price	72.97	$ 82.42
Nonvested, Weighted Average Exercise Price	13.49
Exercisable, Weighted Average Exercise Price	$ 86.25
Weighted Average Remaining Contractual Term (years)
Weighted Average Remaining Contractual Term (years)	5 years 6 months	5 years 2 months 12 days
Granted, Weighted Average Remaining Contractual Term (years)	9 years 8 months 12 days
Nonvested, Weighted Average Remaining Contractual Term (years)	9 years 4 months 24 days
Exercisable, Weighted Average Remaining Contractual Term (years)	4 years 7 months 6 days
Aggregate Intrinsic Value
Shares, Outstanding, Aggregate Intrinsic Value	$ 3,723	$ 1,951
Exercised, Aggregate Intrinsic Value	5
Exercisable, Aggregate Intrinsic Value	$ 2,329