Summary of Warrant Activity (Detail) - Warrants shares in Thousands	6 Months Ended
	Jun. 30, 2020 $ / shares shares
Class Of Warrant Or Right [Line Items]
Beginning Balance | shares	2,083
Granted or Issued | shares	10,864
Ending Balance | shares	12,947
Warrants exercisable at June 30, 2020 | shares	12,947
Beginning Balance | $ / shares	$ 6.12
Granted or Issued | $ / shares	0.51
Ending Balance | $ / shares	1.39
Warrants exercisable at June 30, 2020 | $ / shares	$ 1.39