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Accrued Liabilities - Summary of Accrued Liabilities (Detail) - USD ($)
$ in Thousands
Mar. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Payables and Accruals [Abstract]      
Accrued payroll and related expenses $ 526 $ 1,643 $ 1,189
Accrued restructuring cost 96 516  
Accrued research and development expenses 627 3,171 1,028
Other 106 153 510
Total accrued liabilities $ 1,355 $ 5,483 $ 2,727