Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accounts payable	$ 1,034	$ 2,887
Accrued goods and services	2,082	5,663
Accrued clinical trial costs	1,683	3,901
Accrued drug purchase costs	4,245	222
Accrued payroll and related benefits	2,315	2,884
Accrued restructuring expenses	921	628	$ 774
Income taxes payable	83
Accrued dividends payable		19
Deferred tax incentives	1,314	1,402
Total accounts payable, accrued expenses and other	$ 13,677	$ 17,606