Leases – Adoption of new lease standard (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
ASSETS
Property, plant and equipment, net	$ 45,815	$ 27,335	$ 27,335
Operating lease right of use assets	21,987	10,424
Finance lease right-of-use assets	3,800	4,500
Other non-current assets	1,966	2,741	2,857
LIABILITIES
Current portion of operating leases	4,745	2,921
Operating leases, less current installments	17,561	7,644
Current portion of long-term debt and finance lease	3,504	2,251	2,251
Finance leases, less current installments	1,879	2,319	2,319
Other non-current liabilities	238	267	$ 524
Finance lease right-of-use assets	3,800	4,500
Current portion of finance lease	1,238	1,500
ASU 2016-02 | Balance without adoption of ASC 842
ASSETS
Property, plant and equipment, net	26,303
Other non-current assets	2,040
LIABILITIES
Current portion of long-term debt and finance lease	3,504
Finance leases, less current installments	1,879
Other non-current liabilities	494
ASU 2016-02 | Adjustment
ASSETS
Property, plant and equipment, net	(19,512)
Operating lease right of use assets	(21,987)	10,424
Other non-current assets	74	(116)
LIABILITIES
Current portion of operating leases	(4,745)	2,921
Operating leases, less current installments	(17,561)	7,644
Other non-current liabilities	$ 256	$ (257)