Note 6 - Investments in Marketable Securities (Details Textual) - USD ($)	1 Months Ended
Feb. 28, 2018	Jun. 30, 2018	Sep. 30, 2017
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax, Total		$ 149,050,000	$ 165,872,000
Deferred Tax Liabilities, Investments		39,683,000	64,550,000
Bonds [Member]
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax, Total			$ 3,348,000
Proceeds from Sale of Available-for-sale Securities, Total	$ 8,125,000
Debt Securities, Available-for-sale, Realized Gain (Loss), Total	3,180,000
Reclassification of Tax Effect from AOCI to Retained Earnings	$ 30,000

Reclassification of stranded tax effects from accumulated other comprehensive income to retained earnings.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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- Definition

Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563

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Amount of deferred tax liability attributable to taxable temporary differences from investments (excludes investments in subsidiaries and equity method investments).

+ References

No definition available.

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26853-111562

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

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