Note 6 - Note Payable - Summary of Note Payable (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
2019 (remaining 9 months)	$ 2,103
2020	2,901
2021	16,673
2022	19,306
2023	6,220
Total payments	47,203
Less: Amount representing interest	(15,135)
Present value of obligations	32,068
Less: Unamortized debt discount	(1,141)
Note payable, noncurrent portion	$ 30,927	$ 30,528

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after accumulated amortization, of debt discount.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying value as of the balance sheet date of notes payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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