Note 8 - Shareholders' Equity (Details Textual) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares
Share Price (in dollars per share) | $ / shares	$ 56.41
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)	225,000	229,000	193,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	$ 8.5	$ 7.9	$ 7.5
Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount | $	$ 1,581
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value | $	113	$ 165	$ 454
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested in Period, Fair Value | $	$ 1,309	$ 1,464	$ 1,783
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)	22,000	40,000	53,000
Excess Tax Deduction Exceeding Related Share-based Compensation, Operating Activities | $	$ 16	$ 143
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-Based Payment Arrangement, Amount | $	$ 5	$ 30
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	12,000	12,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased (in shares)	0
Additional Classes of Stock Authorized	2
Additional Classes of Stock Authorized, Shares Authorized, Per Class (in shares)	1,000,000
Common Stock, Shares Authorized (in shares)	150,000,000	150,000,000
Common Stock, Shares, Outstanding, Ending Balance (in shares)	26,671,000	26,913,000
Common Class B [Member]
Common Stock, Shares, Outstanding, Ending Balance (in shares)	0
NQSO [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	10 years
Restricted Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	3 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value | $	$ 508	$ 492	$ 527
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms (Year)		1 year 2 months 12 days
Share-Based Payment Arrangement, Expense | $	$ 250	$ 525	$ 610
Share-Based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	3 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares)	705
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		1 year 8 months 12 days
Stock Appreciation Rights (SARs) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	0	0	0