Note 4 - Marketable Securities - Maturities of Available-for-sale Securities (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Due within one year, amortized cost	$ 3,081
Due within one year, estimated fair value	3,092
Due after one year through five years, amortized cost	6,757
Due after one year through five years, estimated fair value	6,854
Due after five years, amortized cost
Due after five years, estimated fair value
Total available-for-sale securities, amortized cost	9,838
Total available-for-sale securities, estimated fair value	$ 9,946

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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