Lease liabilities - Schedule of Company's Operating and Finance Lease Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finance lease liability
December 31, 2020	$ 66
December 31, 2021	60
December 31, 2022	60
December 31, 2023	59
Total undiscounted lease payments	245
Less: imputed interest	(37)
Total lease liabilities	208
Less: current portion	(62)	$ (9)
Non-current lease liabilities—December 31, 2019	146	$ 6
Operating lease liability
December 31, 2020	570
December 31, 2021	481
December 31, 2022
December 31, 2023
Total undiscounted lease payments	1,051
Less: imputed interest	(48)
Total lease liabilities	1,003
Less: current portion	(556)
Non-current lease liabilities—December 31, 2019	$ 447