Note 9 - Marketable Securities - Maturities of Held-to-maturity Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Due within one year	$ 37,918
Due in one to five years	10,000
Total marketable securities	$ 47,918	$ 66,100	$ 81,103

Amount of investment in debt security measured at amortized cost (held-to-maturity).

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