Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 1996
Property Subject to or Available for Operating Lease [Line Items]
Term of lease			15 years
Capital leased property	$ 30,829	$ 30,829
Proceeds from assignment of purchase option under lease	0	0	$ 1,669
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]
2015	1,900
2016	1,947
2017	1,995
2018	2,045
2019	2,096
Remainder	17,268
Total minimum obligations	27,251
Less amounts representing interest (ranging from 5.8% to 18.8%)	(7,343)
Net present value of minimum obligations	19,908
Less current portion	(918)	(827)
Capital lease obligations	18,990	19,908
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2015	560
2016	491
2017	491
2018	505
2019	502
Remainder	719
Total minimum lease payments	3,268
Rent expense charged to operations	1,700	1,800	1,100
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Balance Beginning of Year	133	189		$ 113
Accruals	279	125		140
Warranty Expenses	(361)	(181)		$ (64)
Balance End of Year	$ 51	133	189
Capital Lease Obligations [Member]
Property Subject to or Available for Operating Lease [Line Items]
Proceeds from assignment of purchase option under lease			$ 1,700
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	$ 15,700	$ 14,500
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	18.80%
Property [Member]
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments, Fiscal Year Maturity [Abstract]
2015	$ 1,899
2016	1,947
2017	1,995
2018	2,045
2019	2,096
Remainder	17,268
Total minimum obligations	27,250
Less amounts representing interest (ranging from 5.8% to 18.8%)	(7,343)
Net present value of minimum obligations	19,907
Less current portion	(917)
Capital lease obligations	18,990
Property [Member] | Capital Lease Obligations [Member]
Property Subject to or Available for Operating Lease [Line Items]
Term of lease				13 years	20 years
Capital leased property					$ 12,300
Increase in capital leased property				$ 11,700
Capital lease obligations				15,500	$ 12,300
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]
2015	1
2016	0
2017	0
2018	0
2019	0
Remainder	0
Total minimum obligations	1
Less amounts representing interest (ranging from 5.8% to 18.8%)	0
Net present value of minimum obligations	1
Less current portion	(1)
Capital lease obligations	$ 0