Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 1996
Capital Lease Obligations [Abstract]
Term of lease				15 years
Capital leased property	$ 30,832	$ 30,832
Proceeds from assignment of purchase option under lease				$ 1,700
Increase in capital leased property				5,700
Capital lease obligations				22,000
Increase in capital lease obligations				6,700
Net book value of capital asset				$ 18,300
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments, Fiscal Year Maturity [Abstract]
2019	1,996
2020	2,046
2021	2,098
2022	2,149
2023	2,203
Remainder	12,916
Total minimum obligations	23,408
Less amounts representing interest (ranging from 5.8% to 21.8%)	(5,428)
Net present value of minimum obligations	17,980
Less current portion	(1,115)	(1,013)
Capital lease obligations	16,865	17,980
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	885
2020	551
2021	547
2022	394
2023	335
Remainder	28
Total minimum lease payments	2,740
Rent expense charged to operations	1,600	1,600	$ 1,700
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance Beginning of Year	30	51	133
Accruals	0	0	279
Warranty Expenses	0	(21)	(361)
Balance End of Year	$ 30	30	$ 51
Capital Lease Obligations [Member]
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments, Fiscal Year Maturity [Abstract]
Annual rent increase percentage	2.50%
Accumulated amortization for property and equipment under capital leases	$ 17,500	$ 16,300
Capital Lease Obligations [Member] | Minimum [Member]
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments, Fiscal Year Maturity [Abstract]
Interest rate percentage	5.00%
Capital Lease Obligations [Member] | Maximum [Member]
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments, Fiscal Year Maturity [Abstract]
Interest rate percentage	21.80%
Property [Member]
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments, Fiscal Year Maturity [Abstract]
2019	$ 1,995
2020	2,045
2021	2,096
2022	2,149
2023	2,203
Remainder	12,916
Total minimum obligations	23,404
Less amounts representing interest (ranging from 5.8% to 21.8%)	(5,427)
Net present value of minimum obligations	17,977
Less current portion	(1,114)
Capital lease obligations	16,863
Property [Member] | Capital Lease Obligations [Member]
Capital Lease Obligations [Abstract]
Term of lease					13 years	20 years
Capital leased property						$ 12,300
Increase in capital leased property					$ 11,700
Capital lease obligations					15,500
Net book value of capital asset					$ 13,100
Equipment [Member]
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments, Fiscal Year Maturity [Abstract]
2019	1
2020	1
2021	2
2022	0
2023	0
Remainder	0
Total minimum obligations	4
Less amounts representing interest (ranging from 5.8% to 21.8%)	(1)
Net present value of minimum obligations	3
Less current portion	(1)
Capital lease obligations	$ 2