Note 8 - Long-term Debt (Details Textual)	12 Months Ended
Dec. 31, 2017 USD ($)
Minimum [Member] \| Variable Interest Rate Notes [Member]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	3.10%
Debt Instrument, Periodic Payment	$ 5,330
Minimum [Member] \| Fixed Interest Rate Notes [Member]
Debt Instrument, Periodic Payment	$ 255
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	2.75%
Maximum [Member] \| Variable Interest Rate Notes [Member]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	3.60%
Debt Instrument, Periodic Payment	$ 125,833
Maximum [Member] \| Fixed Interest Rate Notes [Member]
Debt Instrument, Periodic Payment	$ 32,840
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	7.61%

Amount of the required periodic payments including both interest and principal payments.

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 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

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Balance Type:	debit
Period Type:	duration

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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- Definition

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