Leases - Components of lease cost (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Lease cost:
Operating lease cost	$ 308
Short-term lease cost	46
Total lease cost	354
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases	$ 334
Weighted average remaining lease term- operating leases	5 years 9 months 18 days
Weighted average discount rate- operating leases	3.08%