SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Disaggregation of revenue
Product sales	$ 143,196	$ 139,165
Incremental costs of obtaining a contract	true
Dealer commission, reimbursed dealer expenses and other similar costs	$ 23,760	20,419
Revenue from contract with customer product and service benchmark \| Customer concentration risk \| Independent third party and affiliates
Disaggregation of revenue
Product sales	$ 38,439	$ 5,462
Concentration risk percentage	26.80%	3.90%
ASU 2014-09
Disaggregation of revenue
Impact of adoption			$ 0

Represents the amount of dealer commission, reimbursed dealer expenses and other similar costs.

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- Definition

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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- Definition

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

+ References

No definition available.

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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

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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- Definition

Indicates (true false) whether practical expedient was elected to recognize incremental cost of obtaining contract as expense when incurred if amortization period would have been one year or less.

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