Debt Obligations - Future Payments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Future principal payments of long-term debt
2019	$ 3,279
2020	13,822
2021	9,817
2023	50,000
Total debt	76,918
Interest expense
Interest expense on notes to former owners	642	$ 365	$ 70
Interest expense on borrowings and unused commitment fees	2,211	1,862	1,251
Letter of credit fees	474	553	657
Amortization of debt financing costs	383	376	367
Total	$ 3,710	$ 3,156	$ 2,345

Represents the amount of fees associated with the letter of credit.

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- Definition

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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- Definition

Represents the charge against earnings during the period for commitment fees and debt issuance expenses.

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

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Amount of interest expense incurred on a debt or other obligation to related party.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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