Note 12 - Fair Value Measurements - Schedule of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Sep. 30, 2025
Available-for-sale debt securities	$ 228,939	$ 262,722
Fair Value, Recurring [Member]
Cash equivalents	191,048	149,790
Investment in equity securities	2,100	2,100
Total assets	422,087	414,633
Net investment hedge	33,304	33,420
Foreign exchange contracts	126	120
Total liabilities	33,430	33,540
Foreign exchange contracts		21
Fair Value, Recurring [Member] | Excluding Convertible Debt Securities [Member]
Available-for-sale debt securities	228,939	262,722
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Cash equivalents	190,549	148,539
Investment in equity securities	0	0
Total assets	198,656	156,566
Net investment hedge	0	0
Foreign exchange contracts	0	0
Total liabilities	0	0
Foreign exchange contracts		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Excluding Convertible Debt Securities [Member]
Available-for-sale debt securities	8,107	8,027
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Cash equivalents	499	1,251
Investment in equity securities	0	0
Total assets	221,331	255,967
Net investment hedge	33,304	33,420
Foreign exchange contracts	126	120
Total liabilities	33,430	33,540
Foreign exchange contracts		21
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Excluding Convertible Debt Securities [Member]
Available-for-sale debt securities	220,832	254,695
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Cash equivalents	0	0
Investment in equity securities	2,100	2,100
Total assets	2,100	2,100
Net investment hedge	0	0
Foreign exchange contracts	0	0
Total liabilities	0	0
Foreign exchange contracts		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Excluding Convertible Debt Securities [Member]
Available-for-sale debt securities	$ 0	$ 0