Other Current Assets- Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets, Current	$ 593	$ 353
Prepaid Insurance	100	100
Chronic Myelogenous Lleukemia [Member]
Other Assets, Current	400	200
Prepaid Expenses [Member]
Other Assets, Current	600	400
Other Prepaid Expenses [Member]
Other Assets, Current	$ 100	$ 100