Note 3 - Investment Securities (Tables)

3 Months Ended

Mar. 31, 2025

Notes Tables

Debt Securities, Held-to-Maturity [Table Text Block]

	March 31, 2025
	Amortized		Gross		Gross
	cost, as		unrealized		unrealized			Estimated
(in thousands)	adjusted		holding gains		holding losses			fair value
Short-term investments:
Obligations of domestic governmental agencies (maturing between April 2025 and January 2026) (held-to-maturity)	$	144,101	$	27	$	(6	)	$	144,122
Total short-term investments	$	144,101	$	27	$	(6	)	$	144,122

	December 31, 2024
	Amortized		Gross		Gross
	cost, as		unrealized		unrealized		Estimated
	adjusted		holding gains		holding losses		fair value
Short-term investments:
Obligations of domestic governmental agencies (maturing between January 2025 and December 2025) (held-to-maturity)	$	131,106	$	64	$	—	$	131,170
Total short-term investments	$	131,106	$	64	$	—	$	131,170