Related Party Transactions - Summary of Private Placement Participation (Detail) - Private Placement $ in Thousands	1 Months Ended
	Dec. 31, 2017 USD ($) shares
Related Party Transaction [Line Items]
Units Purchased | shares	372,956
Subscription Amount | $	$ 3,655
A&B (HK) Company Ltd.
Related Party Transaction [Line Items]
Units Purchased | shares	204,081
Subscription Amount | $	$ 2,000
Director 1
Related Party Transaction [Line Items]
Units Purchased | shares	76,530
Subscription Amount | $	$ 750
Director 2
Related Party Transaction [Line Items]
Units Purchased | shares	51,019
Subscription Amount | $	$ 500
CEO
Related Party Transaction [Line Items]
Units Purchased | shares	25,510
Subscription Amount | $	$ 250
CFO/CEO
Related Party Transaction [Line Items]
Units Purchased | shares	15,816
Subscription Amount | $	$ 155