Note 7 - Share-based Compensation (Details Textual) - USD ($)		3 Months Ended		4 Months Ended	9 Months Ended
	Jun. 07, 2023	Sep. 30, 2023	Sep. 30, 2022	Jun. 07, 2023	Sep. 30, 2023	Sep. 30, 2022
Share-Based Payment Arrangement, Expense, Tax Benefit		$ 310,000	$ 485,000		$ 1,900	$ 608,000
Proceeds from Stock Options Exercised					680,000	178,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount		$ 6,400,000			$ 6,400,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)					2 years 6 months
Employee and Nonemployee Stock Option [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value					$ 3,000,000	1,100,000
Proceeds from Stock Options Exercised					$ 789,000	$ 367,000
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares)					861	1,876
Shares Paid for Tax Withholding for Share Based Compensation Market Price (in dollars per share)					$ 127.05	$ 95.82
Restricted Stock Units (RSUs) [Member]
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares)					20,457	19,425
Shares Paid for Tax Withholding for Share Based Compensation Market Price (in dollars per share)					$ 117.95	$ 67.05
Director [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Net of Forfeitures (in shares)	4,215
Share Price (in dollars per share)	$ 167.98			$ 167.98
President and Chief Executive Officer [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Net of Forfeitures (in shares)				7,935
Share Price (in dollars per share)	$ 111.54			$ 111.54