Note 3 - Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Schedule of Available-for-Sale Securities Reconciliation [Table Text Block]

	As at December 31, 2023
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Available-for-sale - matures within one year:
Corporate bonds	$	27,690	$	4	$	(243	)	$	27,451
Available-for-sale - matures after one year through three years:
Corporate bonds		108,700		278		(3,734	)		105,244
Total	$	136,390	$	282	$	(3,977	)	$	132,695

	As at December 31, 2022
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Available-for-sale - matures within one year:
Corporate bonds	$	17,552	$	—	$	(1,330	)	$	16,222
Available-for-sale - matures after one year through four years:
Corporate bonds		101,355		38		(5,535	)		95,858
Total	$	118,907	$	38	$	(6,865	)	$	112,080

Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block]

	Less than 12 months					12 months or greater
	Fair value		Gross unrealized loss			Fair value		Gross unrealized loss
As of December 31, 2023	$	18,193	$	(49	)	$	86,643	$	(3,928	)
As of December 31, 2022	$	58,706	$	(1,885	)	$	48,539	$	(4,980	)

Schedule of Realized Gain (Loss) [Table Text Block]

	Year ended December 31,
	2021			2022			2023
Gross realized gains from sale of available-for-sale marketable securities	$	43		$	—		$	114
Gross realized losses from sale of available-for-sale marketable securities	$	(30	)	$	(55	)	$	(24	)