Note 8 - Investments in Marketable Securities - Amortized Cost and Estimated Fair Value of Debt Securities as Available for Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Within 1 year, cost	$ 15,726	$ 11,448
Within 1 year, fair value	15,767	11,401
1 to 5 years, cost	88,314	98,487
1 to 5 years, fair value	90,408	97,430
6 to 10 years, cost	40,126	64,932
6 to 10 years, fair value	41,231	62,527
Over 10 years, cost	0	1,200
Over 10 years, fair value	0	1,235
Cost	144,166	176,067
Fair Value	$ 147,406	$ 172,593

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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