Note 4 - Income Taxes (Details Textual) - USD ($)	3 Months Ended	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2019	Apr. 30, 2018	Feb. 01, 2018	Jan. 31, 2018
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%
Income Tax Rate, Transition Tax on Accumulated Foreign Earnings, Percent		15.50%
Transition Tax for Accumulated Foreign Earnings, Liability	$ 700,000	$ 700,000			$ 2,000,000
Tax Cuts and Jobs Act of 2017, Measurement Period Adjustment, Income Tax Expense (Benefit)	(1,300,000)
Undistributed Earnings of Foreign Subsidiaries	89,000,000	89,000,000
Deferred Tax Assets, Valuation Allowance, Total	34,898,000	34,898,000			33,665,000
Sale of Intangible Assets, Additional Tax Basis	10,000,000
Deferred Tax Assets, Net of Valuation Allowance, Total	20,365,000	20,365,000			$ 8,617,000
Operating Loss Carryforwards, Total	38,500,000	38,500,000
Tax Credit Carryforward, Amount	23,200,000	23,200,000
Unrecognized Tax Benefits, Period Increase (Decrease), Total		500,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total		9,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	100,000	100,000
Research Tax Credit Carryforward [Member] | Expiring October 2019 [Member]
Tax Credit Carryforward, Amount	167,000	167,000
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	6,500,000	6,500,000
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member] | California Franchise Tax Board [Member]
Tax Credit Carryforward, Amount	$ 10,800,000	$ 10,800,000
Accounting Standards Update 2016-16 [Member]
Deferred Tax Assets, Net of Valuation Allowance, Total			$ 9,600,000	$ 9,600,000