Note 8 - Benefit Plans - Defined Benefit Plans Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in benefit obligation:
Benefit obligation at beginning of year	$ 27,125	$ 28,386
Service cost	117	108	$ 65
Interest cost	1,084	970	965
Actuarial (gain) loss	3,835	(1,597)
Benefits paid	(3,691)	(742)
Benefit obligation at end of year	28,470	27,125	28,386
Changes in plan assets:
Fair value of plan assets at beginning of year	19,980	22,145
Actual return on assets	3,547	(1,526)
Employer contributions	103	103
Benefits paid	(3,691)	(742)
Fair value of plan assets at end of year	19,939	19,980	$ 22,145
Funded status at end of year	(8,531)	(7,145)
Amounts recognized in balance sheets:
Other assets	1,825	1,663
Other current liabilities	(103)	(103)
Long-term pension liability	(10,253)	(8,705)
Net amount recognized	(8,531)	(7,145)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss	$ 10,828	$ 11,417