Stockholders' Deficit - Summary of Outstanding Warrants to Purchase the Company's Common Stock (Detail) - Common Stock Warrants [Member] - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Class of Warrant or Right [Line Items]
Total Warrants	248,247	385,693
Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 4.47
Total Warrants	72,178	83,726
Warrants issued in 2015 [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 4.47
Expiration Dates	Jun. 30, 2025
Total Warrants	109,908	209,690
Warrants issued in 2016 [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 4.47
Expiration Dates	Jun. 30, 2025
Total Warrants	34,396	34,396
Warrants issued in 2017 [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 4.47
Expiration Dates	Jun. 30, 2025
Total Warrants	31,765	57,881
Minimum [Member] | Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Expiration Dates	Mar. 21, 2024
Maximum [Member] | Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Expiration Dates	Jun. 30, 2025