Note 12 - Commitments and Contingencies (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Litigation Settlement, Expense	$ 3,300
Class Action In United States District Court [Member]
Litigation Settlement, Expense	$ 3,300

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

No definition available.

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