Note 11 - Share-based Compensation - Defined Contribution Plans (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Dec. 31, 2018	Dec. 31, 2019
Contribution to defined contribution plans	$ 10,125	$ 14,230

Amount of discretionary contributions made by an employer to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration