Shareholders' Equity - Summary of Outstanding Warrants for Company's Common Stock (Detail)	3 Months Ended
	Mar. 31, 2021 $ / shares shares
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	42,356,273
Exercise Price One [Member]
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	72,869
Exercise Price | $ / shares	$ 8.98
Expiration Date	2021-06
Exercise Price Two [Member]
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	775,000
Exercise Price | $ / shares	$ 0.01
Expiration Date	2024-10
Exercise Price Three [Member]
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	24,725
Exercise Price | $ / shares	$ 2.87
Expiration Date	2027-04
Exercise Price Four [Member]
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	41,736
Exercise Price | $ / shares	$ 2.87
Expiration Date	2027-06
Exercise Price Five [Member]
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	11,332
Exercise Price | $ / shares	$ 2.87
Expiration Date	2028-12
Exercise Price Six [Member]
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	5,780,537
Exercise Price | $ / shares	$ 0.001
Expiration Date	None
Exercise Price Seven [Member]
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	3,474,902
Exercise Price | $ / shares	$ 1.48
Expiration Date	Earlier of December 2021 or 30 days after clinical milestone
Exercise Price Eight [Member]
Class Of Warrant Or Right [Line Items]
Shares Underlying Outstanding Warrants	32,175,172
Exercise Price | $ / shares	$ 0.001
Expiration Date	None