Leases - Adoption of new lease standard (Details) - USD ($)	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
ASSETS
Property, plant and equipment, net	$ 52,525,000	$ 27,335,000	$ 27,335,000	$ 15,000,000
Operating lease right of use assets	20,785,000	10,424,000
Finance lease right-of-use assets	5,800,000	4,500,000
Other non-current assets	3,214,000	2,741,000	2,857,000
LIABILITIES
Current portion of operating leases	4,619,000.00	2,921,000
Operating leases, less current installments	16,580,000.00	7,644,000
Current portion of long-term debt and finance lease	3,821,000	2,251,000	2,251,000
Finance leases, less current installments	3,331,000	2,319,000	2,319,000
Other non-current liabilities	117,000	267,000	524,000
Current portion of finance lease	1,573,000	1,500,000	$ 1,455,000
ASU 2016-02 | Previously reported
ASSETS
Property, plant and equipment, net	52,525,000
Other non-current assets	3,276,000
LIABILITIES
Current portion of long-term debt and finance lease	3,821,000
Finance leases, less current installments	3,331,000
Other non-current liabilities	485,000
ASU 2016-02 | Adjustment
ASSETS
Operating lease right of use assets	(20,785,000)	10,424,000
Other non-current assets	62,000	(116,000)
LIABILITIES
Current portion of operating leases	(4,619,000)	2,921,000
Operating leases, less current installments	(16,580,000)	7,644,000
Other non-current liabilities	$ 368,000	$ (257,000)