Shareholders' Equity - Company's Outstanding and Exercisable Warrants (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Apr. 06, 2018
Class of Warrant or Right [Line Items]
Exercise Price		$ 2.00
Total Warrants Outstanding	7,371,925
Exercisable Warrants Outstanding	7,371,925
Class One [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 3.10
Total Warrants Outstanding	48,387
Exercisable Warrants Outstanding	48,387
Expiration Date	Sep. 19, 2022
Class Two [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 3.10
Total Warrants Outstanding	462,106
Exercisable Warrants Outstanding	462,106
Expiration Date	May 10, 2024
Class Three [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 3.10
Total Warrants Outstanding	602,414
Exercisable Warrants Outstanding	602,414
Expiration Date	Jul. 25, 2024
Class Four [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 3.10
Total Warrants Outstanding	1,064,518
Exercisable Warrants Outstanding	1,064,518
Expiration Date	Nov. 08, 2024
Class Five [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 2.00
Total Warrants Outstanding	900,000
Exercisable Warrants Outstanding	900,000
Expiration Date	Apr. 10, 2023
Class Six [Member]
Class of Warrant or Right [Line Items]
Exercise Price	$ 1.00
Total Warrants Outstanding	4,294,500
Exercisable Warrants Outstanding	4,294,500
Expiration Date	Jul. 17, 2025