Note 8 - Long-term Debt and Credit Facility - Long-term Debt (Details) (Parentheticals)	Mar. 31, 2020	Dec. 31, 2019
Medium-term Notes [Member]
Current effective interest rate	3.35%	4.09%
Line of Credit [Member]
Current effective interest rate	3.11%	4.01%
Notes Payable, Other Payables [Member] \| Minimum [Member]
Current effective interest rate	3.30%	3.30%
Notes Payable, Other Payables [Member] \| Maximum [Member]
Current effective interest rate	7.80%	7.80%

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 3: 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=120391452&loc=d3e13212-122682

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