Other Current Assets- Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Other Assets, Current	$ 281	$ 353
Acute Myeloid Leukemia
Other Assets, Current	200
Prepaid Expenses
Other Assets, Current	300
Other Prepaid Expenses [Member]
Other Assets, Current		$ 400
Prepaid Insurance	$ 100