Other Current Assets- Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Other Assets Current	$ 902	$ 179
Acute Myeloid Leukemia [Member]
Other Assets Current	600
Prepaid Expenses [Member]
Other Assets Current		$ 200
Other Prepaid Expenses [Member]
Other Assets Current	$ 300