Principal Business Activity and Significant Accounting Policies - Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Receivables and Credit Policy
Accounts receivable, gross	$ 22,486	$ 18,526
Less: Allowance for doubtful accounts	(343)	(498)
Non-current portion of receivables	(384)	(833)
Total accounts receivable, net	21,759	17,195
Trade receivables
Receivables and Credit Policy
Accounts receivable, gross	22,189	18,086
Notes receivable
Receivables and Credit Policy
Accounts receivable, gross	$ 297	$ 440
Notes receivable \| Maximum
Receivables and Credit Policy
Fixed interest rate	4.00%
Notes receivable \| Minimum
Receivables and Credit Policy
Fixed interest rate	0.00%

Accounts Receivable Noncurrent

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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.

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- Definition

For unclassified balance sheet, amounts due from customers or clients for goods or services that have been delivered or sold in the normal course of business.

+ References

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- Definition

For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

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- Definition

For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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