Note 2 - Summary of Significant Accounting Policies - Accounts Receivable, Net, Deferred Revenue and Deferred Sales Commissions (Details) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Opening, accounts receivable, net	[1]	$ 53,749	$ 43,619	$ 43,619
Opening, deferred revenue		74,688	60,600	60,600
Opening, deferred sales commissions		31,943	28,351	28,351
Closing, accounts receivable, net	[1]	60,330		53,749
Closing, deferred revenue		78,126		74,688
Closing, deferred sales commissions		35,267		31,943
Increase/(decrease), accounts receivable, net	[1]	6,581		10,130
Deferred revenue		5,377	$ 4,965	14,088
Increase/(decrease), deferred sales commissions		3,324		$ 3,592
Increase/(decrease), deferred revenue		$ 3,438

[1] Accounts receivable, net is inclusive of accounts receivable, net of allowance for doubtful accounts, short-term unbilled receivables and long-term unbilled receivables.