Capital Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Capital Leases
Total assets under capital leases	$ 3,100	$ 2,500
Accumulated depreciation of assets under capital leases	1,900	2,300
Net book value of assets under capital leases	1,200	200
Future minimum lease payments required under capital leases
2018	134
2019	98
2020	90
2021	11
Total minimum lease payments	333
Amounts representing interest	(5)
Net present value of minimum lease payments	328
Less: current portion of capital lease obligations	(132)	(188)
Long-term capital lease obligation	$ 196	$ 15

Amount of capital lease obligation due within one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid more than one year (or one operating cycle, if longer) after the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Publisher FASB
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Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

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The total gross amount less the charge for the use of the long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

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Amount of minimum lease payments for capital leases.

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Amount of minimum lease payments for capital leases due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount necessary to reduce net minimum lease payments to present value for capital leases.

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Present value of minimum lease payments for capital leases net of executory costs, including amounts paid by the lessee to the lessor for insurance, maintenance and taxes.

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The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

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