Leases - Lease expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Lease cost:
Operating lease cost	$ 1,071
Short-term lease cost	37
Variable lease cost	217
Finance lease cost:
Total net lease cost	2,059
Cost of goods sold
Finance lease cost:
Amortization of leased assets	520
Interest Expense.
Finance lease cost:
Interest on lease liabilities	$ 214