Note 8 - Investments in Marketable Securities - Marketable Securities and Restricted Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Restricted investments available for sale, amortized cost	$ 144,166	$ 176,067
Restricted investments available for sale, fair value	147,406	172,593
Investments available for sale, amortized cost	174,342	206,243
Investments available for sale, fair value	299,859	312,816
Equity Securities [Member]
Unrestricted investments available for sale, amortized cost	30,176	30,176
Unrestricted investments available for sale, fair value	152,453	140,223
Corporate Debt Securities [Member]
Restricted investments available for sale, amortized cost	63,414	69,439
Restricted investments available for sale, fair value	65,653	67,632
Collateralized Mortgage Backed Securities [Member]
Restricted investments available for sale, amortized cost	54,451	62,772
Restricted investments available for sale, fair value	55,185	62,068
US Government Corporations and Agencies Securities [Member]
Restricted investments available for sale, amortized cost	13,379	22,038
Restricted investments available for sale, fair value	13,410	21,457
US States and Political Subdivisions Debt Securities [Member]
Restricted investments available for sale, amortized cost	12,922	21,818
Restricted investments available for sale, fair value	$ 13,158	$ 21,436

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
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Amount 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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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