For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount of lease income from operating, direct financing, and sales-type leases. Includes, but is not limited to, variable lease payments, interest income, profit (loss) recognized at commencement, and lease payments paid and payable to lessor.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Industry, Geographic and Revenue Disaggregation - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) segment	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting [Abstract]
Number of operating segments \| segment			1
Segment Reporting Information [Line Items]
Trade accounts receivable	$ 1,911		$ 1,911		$ 1,860
Lease Income	$ 200		$ 400
Lease income		$ 200		$ 200
Geographic concentration \| Foreign \| Total revenue
Segment Reporting Information [Line Items]
Risk concentration	24.00%	28.00%	28.00%	27.00%
Geographic concentration \| Foreign \| Net accounts receivable
Segment Reporting Information [Line Items]
Trade accounts receivable	$ 1,100		$ 1,100		$ 900