Warrants - Summary of Common Stock Warrants Outstanding (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	10,384,706	7,344,297	78,336
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	62	1,612
Per Share Exercise Price	$ 80.10	$ 80.10
Issuance Date	Aug. 16, 2017	Aug. 16, 2017
Expiration Date	Aug. 16, 2022	Aug. 16, 2022
Warrants Issued with Common Units in Unit Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	2,505,250	2,516,250
Per Share Exercise Price	$ 2.75	$ 4.18
Issuance Date	Oct. 02, 2018	Oct. 02, 2018
Expiration Date	Oct. 02, 2023	Oct. 02, 2023
Underwriter Warrant Issued with Public Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	196,650	196,650
Per Share Exercise Price	$ 6.25	$ 6.25
Issuance Date	Oct. 02, 2018	Oct. 02, 2018
Expiration Date	Sep. 28, 2021	Sep. 28, 2021
Issued With Common Units in the Second Registered Direct Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	4,629,630	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 the Third Registered Direct Offering [Member]
Class of Warrant or Right [Line Items]
Number of Common Stock Warrants	3,052,959
Per Share Exercise Price	$ 3.21
Issuance Date	Mar. 12, 2019
Expiration Date	Mar. 12, 2024