Note 13 - Employee Retirement Plans - Assumed Health Care Trend Rates (Details)	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Health care cost trend rate assumed for next year	6.25%	6.50%
Rate that the cost trend rate gradually declines to	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2027	2027

Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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- Definition

Ultimate trend rate for health care cost for defined benefit postretirement plan.

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- Definition

Year ultimate health care cost trend rate is expected to be reached, in YYYY format.

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