Note 12 - Pension and Other Postretirement Benefit Plans - Effect of a One Percentage Point Change in Assumed Health Care Trend Rates (Details) $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($)
Effect of a 1% increase on postretirement benefit obligation	$ 1,614
Effect of a 1% decrease on postretirement benefit obligation	(1,230)
Effect of a 1% increase on total service and interest cost	159
Effect of a 1% decrease on total service and interest cost	$ (118)

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

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

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- Definition

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

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- Definition

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

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The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

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