Summary of Significant Accounting Policies - Recently issued pronouncements (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Sep. 30, 2019
Recently Issued Pronouncement
Practical expedient - package	true
Right-of-use assets		$ 2,595
Operating leases liabilities		$ 2,913
ASU 2016-02
Recently Issued Pronouncement
Right-of-use assets	$ 3,600
Operating leases liabilities	4,000
Derecognized deferred rent liability	$ 390