Note 17 - Weighted-average Assumption Used to Determine Net Post-retirement Benefit Cost (Details) - Other Postretirement Benefit Plans [Member]	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted Average Assumption Used To Determine Net Postretirement Benefit Cost [Line Items]
Effective rate for interest cost	2.85%	3.49%	4.28%
Salary increase rate	1.80%	2.60%	2.50%

Expected rate of compensation increases (for pay-related plans).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration