Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accounts payable	$ 271	$ 1,034
Accrued goods and services	372	2,082
Accrued clinical trial costs	320	1,683
Accrued drug purchase costs	371	4,245
Accrued payroll and related benefits		2,315
Accrued restructuring expenses	66	921	$ 628
Income taxes payable		83
Deferred tax incentives	1,314	1,314
Total accounts payable, accrued expenses and other	$ 2,714	$ 13,677