Note 8 - Fair Value Measurements - Summary of Fair Value Measurements by Level (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Equity Securities [Member]
Available-for-sale securities	$ 147,017	$ 116,168
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities	34,538	32,683
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Commercial Mortgage Backed Securities [Member]
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Available-for-sale securities	27,188	21,033
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	19,212	38,208
Restricted cash and cash equivalents	17,158	11,106
Total financial assets	245,113	219,198
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Equity Securities [Member]
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities	33,288	38,460
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Commercial Mortgage Backed Securities [Member]
Available-for-sale securities	53,913	60,910
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities [Member]
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities	29,959	16,780
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents
Restricted cash and cash equivalents
Total financial assets	117,160	116,150
Fair Value, Measurements, Recurring [Member] \| Equity Securities [Member]
Available-for-sale securities	147,017	116,168
Fair Value, Measurements, Recurring [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities	67,826	71,143
Fair Value, Measurements, Recurring [Member] \| Commercial Mortgage Backed Securities [Member]
Available-for-sale securities	53,913	60,910
Fair Value, Measurements, Recurring [Member] \| US Treasury Securities [Member]
Available-for-sale securities	27,188	21,033
Fair Value, Measurements, Recurring [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities	29,959	16,780
Fair Value, Measurements, Recurring [Member]
Cash and cash equivalents	19,212	38,208
Restricted cash and cash equivalents	17,158	11,106
Total financial assets	362,273	335,348
Available-for-sale securities	$ 325,903	$ 286,034

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)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

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)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ 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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- Definition

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
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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