Stockholders' Equity - Summary of Outstanding Warrants (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Jul. 30, 2018	Mar. 09, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding			39,100
Common Shares, Price per Share		$ 3.50	$ 11.40
(1) Warrants Related to February 2015 agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	306
Common Shares, Currently Exercisable	306
Common Shares, Price per Share	$ 450.45
Common Shares, Expiration Date	Feb. 13, 2020
(2) Warrants Related to March 2015 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	10,209
Common Shares, Currently Exercisable	10,209
Common Shares, Price per Share	$ 244.88
Common Shares, Expiration Date	Sep. 24, 2020
(3) Warrants Related to March 2015 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	1,021
Common Shares, Currently Exercisable	1,021
Common Shares, Price per Share	$ 306.09
Common Shares, Expiration Date	Mar. 20, 2020
(4) Warrants related to October 2015 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	135,517
Common Shares, Currently Exercisable	135,517
Common Shares, Price per Share	$ 60.00
Common Shares, Expiration Date	Oct. 14, 2020
(5) Warrants Related to October 2015 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	9,034
Common Shares, Currently Exercisable	9,034
Common Shares, Price per Share	$ 65.63
Common Shares, Expiration Date	Oct. 14, 2020
(6) Warrants related to August 2016 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	53,506
Common Shares, Currently Exercisable	53,506
Common Shares, Price per Share	$ 30.00
Common Shares, Expiration Date	Feb. 02, 2022
(7) Warrants Related to August 2016 Financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	4,994
Common Shares, Currently Exercisable	4,994
Common Shares, Price per Share	$ 38.55
Common Shares, Expiration Date	Aug. 02, 2021
(8) Warrants related to December 2016 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	685,667
Common Shares, Currently Exercisable	685,667
Common Shares, Price per Share	$ 20.00
Common Shares, Expiration Date	Dec. 14, 2021
(9) Warrants related to March 2018 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	158,100
Common Shares, Currently Exercisable	158,100
Common Shares, Price per Share	$ 11.40
Common Shares, Expiration Date	Sep. 09, 2023
(10) Warrants related to March 2018 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	11,067
Common Shares, Currently Exercisable	11,067
Common Shares, Price per Share	$ 15.80
Common Shares, Expiration Date	Mar. 06, 2023
(11) Warrants related to July 2018 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	2,571,429
Common Shares, Currently Exercisable	2,571,429
Common Shares, Price per Share	$ 3.50
Common Shares, Expiration Date	Jul. 25, 2023
(12) Warrants Related to July 2018 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	154,286
Common Shares, Currently Exercisable	154,286
Common Shares, Price per Share	$ 4.38
Common Shares, Expiration Date	Jul. 25, 2023
(13) Warrants related to May 2019 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	119,000	154,286
Common Shares, Currently Exercisable	119,000
Common Shares, Price per Share	$ 1.25	$ 4.375
Common Shares, Expiration Date	May 23, 2024
(14) Warrants related to October 2019 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	11,438,716
Common Shares, Currently Exercisable	11,438,716
Common Shares, Price per Share	$ 0.25
Common Shares, Expiration Date	Oct. 10, 2024
(15) Warrants related to October 2019 financing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding	828,380
Common Shares, Currently Exercisable	0
Common Shares, Price per Share	$ 0.31
Common Shares, Expiration Date	Oct. 08, 2024