Warrants - Summary of Common Stock Warrants Outstanding (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 02, 2018
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	1,777,611	10,384,706	7,344,297
Replacement Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	155	155
Per Share Exercise Price	$ 483.00	$ 483.00
Issuance Date	Mar. 03, 2012	Mar. 03, 2012
Expiration Date	Mar. 03, 2022	Mar. 03, 2022
Warrants Issued with Redeemable Preferred [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	1,420	62
Per Share Exercise Price	$ 3.50	$ 80.10
Issuance Date	Aug. 16, 2017	Aug. 16, 2017
Expiration Date	Aug. 16, 2022	Aug. 16, 2022
Warrants Issued With Common Units In 2018 Unit Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	3,300	2,505,250
Per Share Exercise Price	$ 2.7568	$ 2.7568
Issuance Date	Oct. 02, 2018	Oct. 02, 2018
Expiration Date	Oct. 02, 2023	Oct. 02, 2023
Underwriter Warrant Issued In 2018 Unit Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants		196,650		196,650
Per Share Exercise Price		$ 6.25
Issuance Date		Oct. 02, 2018
Expiration Date		Sep. 28, 2021
Issued With Common Units In 2018 Registered Direct Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	92,300	4,629,630
Per Share Exercise Price	$ 5.40	$ 5.40
Issuance Date	Oct. 10, 2018	Oct. 10, 2018
Expiration Date	Oct. 10, 2023	Oct. 10, 2023
Issued with Common Units in Registered Direct Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	50,000	3,052,959
Per Share Exercise Price	$ 3.21	$ 3.21
Issuance Date	Mar. 12, 2019	Mar. 12, 2019
Expiration Date	Mar. 12, 2024	Mar. 12, 2024
Issued with Common Units in Public Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	1,630,436
Per Share Exercise Price	$ 0.0001
Issuance Date	Jul. 16, 2020