Note 9 - Employee Retirement Plans - Pension Plan Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair value of plan assets	$ 30,843	$ 45,378	$ 56,779	$ 56,495
Pension Plan [Member] \| Change In Plan Assets [Member]
Fair value of plan assets	30,843	45,378
Pension Plan [Member] \| Fair Value, Inputs, Level 1 [Member] \| Change In Plan Assets [Member]
Fair value of plan assets	14,508	30,281
Pension Plan [Member] \| Fair Value, Inputs, Level 2 [Member] \| Change In Plan Assets [Member]
Fair value of plan assets	10,831	11,895
Pension Plan [Member] \| Fair Value, Inputs, Level 3 [Member] \| Change In Plan Assets [Member]
Fair value of plan assets	5,504	3,202
Pension Plan [Member] \| Fair Value Measured at Net Asset Value Per Share [Member] \| Change In Plan Assets [Member]
Fair value of plan assets	0	0
Pension Plan [Member] \| Defined Benefit Plan, Equity Securities [Member]
Fair value of plan assets	19,773	31,196
Pension Plan [Member] \| Defined Benefit Plan, Equity Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value of plan assets	14,212	26,847
Pension Plan [Member] \| Defined Benefit Plan, Equity Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value of plan assets	57	1,147
Pension Plan [Member] \| Defined Benefit Plan, Equity Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value of plan assets	5,504	3,202
Pension Plan [Member] \| Defined Benefit Plan, Equity Securities [Member] \| Fair Value Measured at Net Asset Value Per Share [Member]
Fair value of plan assets	0	0
Pension Plan [Member] \| Defined Benefit Plan, Debt Security [Member]
Fair value of plan assets	10,058	12,928
Pension Plan [Member] \| Defined Benefit Plan, Debt Security [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value of plan assets	296	3,434
Pension Plan [Member] \| Defined Benefit Plan, Debt Security [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value of plan assets	9,762	9,494
Pension Plan [Member] \| Defined Benefit Plan, Debt Security [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value of plan assets	0	0
Pension Plan [Member] \| Defined Benefit Plan, Debt Security [Member] \| Fair Value Measured at Net Asset Value Per Share [Member]
Fair value of plan assets	0	0
Pension Plan [Member] \| Defined Benefit Plan, Cash and Cash Equivalents [Member]
Fair value of plan assets	1,012	1,254
Pension Plan [Member] \| Defined Benefit Plan, Cash and Cash Equivalents [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair value of plan assets	0	0
Pension Plan [Member] \| Defined Benefit Plan, Cash and Cash Equivalents [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value of plan assets	1,012	1,254
Pension Plan [Member] \| Defined Benefit Plan, Cash and Cash Equivalents [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value of plan assets	0	0
Pension Plan [Member] \| Defined Benefit Plan, Cash and Cash Equivalents [Member] \| Fair Value Measured at Net Asset Value Per Share [Member]
Fair value of plan assets	$ 0	$ 0