Leases - Lease Cost (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($) lease_arrangement
Lessee, Lease, Description [Line Items]
Number of lease arrangements | lease_arrangement		10
Operating lease cost	$ 171	$ 343
Short-term lease cost	0	68
Total lease cost	$ 171	$ 411
Weighted average remaining lease term	4 years 4 months 6 days	4 years 4 months 6 days
Weighted average discount rate	3.61%	3.61%
Minimum
Lessee, Lease, Description [Line Items]
Term of lease	1 year	1 year
Maximum
Lessee, Lease, Description [Line Items]
Term of lease	6 years	6 years