Leases - Net Lease Cost and Other Selected Information (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Net lease cost:
Operating lease cost	$ 466	$ 932
Variable lease cost	(43)	(89)
Sub lease income	(44)	(88)
Net lease cost	$ 379	$ 755
Weighted average remaining lease term	14 years	14 years
Weighted average discount rate	3.40%	3.40%