Note 8 - Summary of Fair Value Measurements by Level (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Inputs, Level 1 [Member] \| Equity Securities [Member]
Marketable equity securities	$ 125,871	$ 116,168
Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member]
Marketable equity securities	$ 32,936	$ 32,683
Fair Value, Inputs, Level 1 [Member] \| Commercial Mortgage Backed Securities [Member]
Marketable equity securities
Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Marketable equity securities	$ 20,187	$ 21,033
Fair Value, Inputs, Level 1 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Marketable equity securities
Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	$ 49,183	$ 38,208
Restricted cash and cash equivalents	14,455	11,106
Total financial assets	$ 242,632	$ 219,198
Fair Value, Inputs, Level 2 [Member] \| Equity Securities [Member]
Marketable equity securities
Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Marketable equity securities	$ 39,786	$ 38,460
Fair Value, Inputs, Level 2 [Member] \| Commercial Mortgage Backed Securities [Member]
Marketable equity securities	$ 59,460	$ 60,910
Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities [Member]
Marketable equity securities
Fair Value, Inputs, Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Marketable equity securities	$ 15,804	$ 16,780
Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents
Restricted cash and cash equivalents
Total financial assets	$ 115,050	$ 116,150
Equity Securities [Member]
Marketable equity securities	125,871	116,168
Corporate Debt Securities [Member]
Marketable equity securities	72,722	71,143
Commercial Mortgage Backed Securities [Member]
Marketable equity securities	59,460	60,910
US Treasury Securities [Member]
Marketable equity securities	20,187	21,033
US States and Political Subdivisions Debt Securities [Member]
Marketable equity securities	15,804	16,780
Cash and cash equivalents	49,183	38,208
Restricted cash and cash equivalents	14,455	11,106
Marketable equity securities	294,044	286,034
Total financial assets	$ 357,682	$ 335,348

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 1
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

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The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.5-02.1)
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