Supplemental Balance Sheet Information - Customer Financing Leases Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Total minimum lease payments to be received	$ 103,013	$ 109,431
Less: Amounts representing estimated executing costs	(25,836)	(27,815)
Net present value of minimum lease payments to be received	77,177	81,616
Estimated residual value of leased assets	1,051	1,051
Less: Unearned income	(4,197)	(4,781)
Net investment in sales-type financing leases	74,031	77,886
Less: Current portion	(5,496)	(5,209)
Non-current portion of investment in sales-type financing leases	$ 68,535	$ 72,677

Capital Leases, Net Investment in Sales Type Leases, Minimum Payments to be Received, Net of Executory Costs

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- Definition

The net amount due within one year of the balance sheet date or the normal operating cycle, if longer, consisting of: (a) minimum lease payments on sales type leases and (b) unguaranteed residual value; less: (i) executory costs, (ii) unearned income, and (iii) the accumulated allowance for uncollectible minimum lease payments.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)
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The net amount due after one year of the balance sheet date or beyond the normal operating cycle, if longer, consisting of: (a) minimum lease payments on sales type leases, and (b) unguaranteed residual value; less: (i) executory costs, (ii) unearned income, and (iii) the accumulated allowance for uncollectible minimum lease payments.

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The net investment in sales type leases as of the balance sheet date consisting of: (a) minimum lease payments on sales type leases and (b) unguaranteed residual value; less: (i) executory costs, (ii) unearned income, and (iii) the accumulated allowance for uncollectible minimum lease payments.

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The remaining (unamortized) difference between the gross investment in a sales-type lease and the cost or carrying amount of the leased property as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(4)
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Estimated remaining costs to be incurred to service the sales-type lease, such as taxes, maintenance and insurance and the profit thereon, that are included in the minimum lease payments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(1)(i)
-URI http://asc.fasb.org/extlink&oid=84165051&loc=d3e45377-112738

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Amount of remaining payments as of the balance sheet date that lessees are obligated to make or can be required to make under sales-type leases, including any guarantee of residual value and executory costs. The amount also includes any guaranteed rental payments by an unrelated third-party provided that are financially capable of making such payments.

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-Publisher FASB
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The estimate of the lease property's economic value at the end of the sales-type lease term excluding any amounts guaranteed by either the lessee or a third-party.

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