Note 3 - Supplemental Balance Sheet Information (in Thousands) - Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accounts receivable	$ 54,735	$ 47,477
Less allowance for doubtful accounts	(564)	(563)
Accounts receivable, net	54,171	46,914
Trade Accounts Receivable [Member]
Accounts receivable	44,424	37,502
Unbilled [Member]
Accounts receivable	8,168	7,369
Non-Trade [Member]
Accounts receivable	$ 2,143	$ 2,606