Note 3 - Investment Securities (Tables)

12 Months Ended

Dec. 31, 2024

Notes Tables

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

	December 31, 2024
	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 January 2025 and December 2025) (held-to-maturity)	$	131,106	$	64	$	—	$	131,170
Total short-term investment securities	$	131,106	$	64	$	—	$	131,170

	December 31, 2023
	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 2023 and December 2023) (held-to-maturity)	$	124,575	$	30	$	53	$	124,552
Total short-term and long-term investment securities	$	124,575	$	30	$	53	$	124,552