Lease (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Finance lease cost components:
Amortization of finance lease assets	$ 17	$ 34
Interest on finance lease liabilities	14	30
Total finance lease costs	31	64
Operating lease cost components:
Operating lease cost	123	246
Variable lease cost	27	54
Short-term lease cost	30	52
Total operating lease costs	180	352
Total lease cost	$ 211	$ 416