Note 9 - Investments in Marketable Securities - Amortized Cost and Estimated Fair Value of Debt Securities as Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Within 1 year, cost	$ 14,754	$ 15,726
Within 1 year, fair value	14,600	15,767
1 to 5 years, cost	94,416	88,314
1 to 5 years, fair value	94,603	90,408
6 to 10 years, cost	37,947	40,126
6 to 10 years, fair value	38,608	41,231
Over 10 years, cost	0	0
Over 10 years, fair value	0	0
Cost	147,117	144,166
Fair Value	$ 147,811	$ 147,406

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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