Note 8 - Employee Benefit Plans - Fair Value Measurements (Details) - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Fair value, plan assets		$ 36,187	$ 32,415
Fair Value, Inputs, Level 1 [Member]
Fair value, plan assets		29,127	26,040
Fair Value, Inputs, Level 2 [Member]
Fair value, plan assets		7,060	6,375
Cash [Member]
Fair value, plan assets		1,390	4,336
Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value, plan assets		1,390	4,336
Defined Benefit Plan, Equity Securities, US [Member]
Fair value, plan assets		19,758	15,129
Defined Benefit Plan, Equity Securities, US [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value, plan assets		19,758	15,129
Defined Benefit Plan, Equity Securities, Non-US [Member]
Fair value, plan assets		2,722	2,735
Defined Benefit Plan, Equity Securities, Non-US [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value, plan assets		2,722	2,735
Equity Funds [Member]
Fair value, plan assets	[1]	5,257	3,840
Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value, plan assets	[1]	5,257	3,840
US States and Political Subdivisions Debt Securities [Member]
Fair value, plan assets		57	152
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value, plan assets		57	152
Corporate Debt Securities [Member]
Fair value, plan assets	[2]	7,003	6,223
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value, plan assets	[2]	$ 7,003	$ 6,223

[1] This category comprises actively managed equity funds invested in large-cap and mid-cap U.S. companies.

[2] This category represents investment grade bonds of U.S. issuers from diverse industries.