Note 2 - Investments - Contractual Maturities of Available-for-sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Due in one year or less, cost	$ 88,803
Due in one year or less, fair value	89,049
Due between one and five years, cost	50,645
Due between one and five years, fair value	51,082
Available-for-sale securities, cost	139,448	$ 235,766
Available-for-sale securities, fair value	$ 140,131	$ 235,339

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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