Lease liabilities - Schedule of Company's Operating and Finance Lease Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Finance lease liability
December 31, 2020 (remaining nine months)	$ 62
December 31, 2021	60
December 31, 2022	60
December 31, 2023	60
Total undiscounted lease payments	242
Less: imputed interest	(37)
Total lease liabilities	205
Less: current portion	(59)	$ (62)
Non-current lease liabilities – March 31, 2020	146	146
Operating lease liability
December 31, 2020 (remaining nine months)	414
December 31, 2021	2,502
December 31, 2022	2,086
December 31, 2023	2,139
December 31, 2024	2,192
Thereafter	9,124
Total undiscounted lease payments	18,457
Less: imputed interest	(7,734)
Total lease liabilities	10,723
Less: current portion	(541)	(556)
Non-current lease liabilities – March 31, 2020	$ 10,182	$ 447