Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts Payable and Accrued Liabilities
Accounts payable	$ 3,787	$ 4,517
Accrued expenses	3,247	2,004
Accrued compensation	7,936	6,477
Accounts Payable and Accrued Expenses	$ 14,970	$ 12,998