Leases - Lease costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases
Operating lease cost	$ 648	$ 650	$ 1,297	$ 1,299
Variable lease cost	38	47	59	57
Total lease costs	686	697	1,356	1,356
Cash paid for amounts included in the measurement of lease liabilities	566	$ 344	1,123	$ 854
ROU assets exchanged for lease liabilities	$ 100		$ 100
Remaining lease term	5 years 2 months 12 days		5 years 2 months 12 days
Discount rate	5.50%		5.50%