Prepaid Expenses and Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Prepaid Expenses and Other Assets
Prepaid insurance	$ 297	$ 358
Right of use assets	42
Deferred offering costs	534	569
Recoupable deposits and other	376	261
Prepaid expenses and other assets	$ 1,249	$ 1,188