Note 15 - Employee Benefit Plans - Amounts Recognized in Balance Sheet (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Benefit obligation	$ 5,222	$ 4,493	$ 5,223
Fair value of assets	9,157	8,092	$ 8,513
Interest cost	182	173
Grayson Plan [Member]
Plan benefit cost	5,169	4,912
Unrecognized net actuarial loss	(1,234)	(1,313)
Amount recognized in other assets	3,935	3,599
Unrecognized net actuarial loss	(1,234)	(1,313)
Deferred taxes	259	275
Amount recognized in accumulated comprehensive income (loss), net	(975)	(1,038)
Benefit obligation	5,222	4,493
Fair value of assets	9,157	8,092
Unrecognized net actuarial loss	1,234	1,313
Prepaid benefit cost	5,169	4,912
Interest cost	182	173
Expected return on plan assets	(551)	(576)
Recognized net loss due to settlement	71
Recognized net actuarial loss	41	30
Net periodic benefit expense	(257)	(373)
Accumulated benefit obligation	5,222	4,493
Vested benefit obligation	$ 5,222	$ 4,493
Discount rate used for net periodic pension cost	4.25%	3.50%
Discount rate used for disclosure	3.25%	4.25%
Expected return on plan assets	7.00%	7.00%
Rate of compensation increase