Segment Reporting - Additional Information (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments \| Segment	1
Description of long-lived assets located	Substantially all of our long-lived assets are located in the United States.
Total revenue	$ 125,300	$ 112,287	$ 78,479
United States
Segment Reporting Information [Line Items]
Total revenue	$ 28,800	$ 25,900	$ 21,000
Readers and Gateways
Segment Reporting Information [Line Items]
Percentage of Revenue	19.00%	16.00%	22.00%

Percentage of revenue.

No definition available.

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- Definition

Disclosures about long-lived assets (except financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets) that are (1) located in the entity's country of domicile, and (2) located in all foreign countries in which the entity holds assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=68060357&loc=d3e9038-108599

+ Details

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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- Definition

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.

+ References

No definition available.

+ Details

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- Details

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Namespace Prefix:
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Period Type:

- Details

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