Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accounts payable	$ 710	$ 1,034
Accrued goods and services	1,399	2,082
Accrued clinical trial costs	684	1,683
Accrued drug purchase costs	371	4,245
Accrued payroll and related benefits		2,315
Accrued restructuring expenses	122	921
Income taxes payable	83	83
Deferred tax incentives	1,314	1,314
Total accounts payable, accrued expenses and other	$ 4,683	$ 13,677