Note 21 - Weighted-average Assumption Used to Determine Net Post-retirement Benefit Cost (Details) - Other Postretirement Benefits Plan [Member]	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Weighted Average Assumption Used To Determine Net Postretirement Benefit Cost [Line Items]
Effective rate for interest cost	3.26%	2.88%
Salary increase rate	2.35%	2.35%

Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration