Note 7 - Debt - Current and Long-term Debt (Details) (Parentheticals)	Jun. 30, 2018	Dec. 31, 2017
Revenue Equipment Installment Notes [Member]
Long term debt, interest rate	3.60%	3.30%
Real Estate Note [Member]
Long term debt, interest rate	3.70%	3.10%

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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