Note 7 - Accounting for Share-based Payment Arrangement Compensation (Details Textual) - USD ($)	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Stock or Unit Option Plan Expense	$ 149,000	$ 290,000
Income Tax Expense (Benefit)	5,583,000	$ 5,717,000
Accounting Standards Update 2016-09 [Member]
Income Tax Expense (Benefit)	$ (95,000)

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration