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, 2018 USD ($)
Effect of a 1% increase on postretirement benefit obligation	$ 1,652
Effect of a 1% decrease on postretirement benefit obligation	(1,277)
Effect of a 1% increase on total service and interest cost	147
Effect of a 1% decrease on total service and interest cost	$ (111)

Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate.

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 (m)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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- Definition

Amount of decrease in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point decrease in assumed health care cost trend rate.

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Amount of increase in accumulated postretirement benefit obligation from one-percentage-point increase in assumed health care cost trend rate.

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Amount of increase in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point increase in assumed health care cost trend rate.

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