Note 11 - Stock-based Compensation (Details Textual)	3 Months Ended	9 Months Ended
	Oct. 31, 2020 USD ($) shares	Oct. 31, 2020 USD ($) shares
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares	200	76,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 9,000	$ 3,200,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	24,800,000	$ 24,800,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		2 years 9 months 18 days
Performance Shares [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares		8,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation		$ 300,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 2,800,000	$ 2,800,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		1 year 2 months 12 days
Stock Appreciation Rights (SARs) [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares	400	57,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 15,000	$ 2,400,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 1,600,000	$ 1,600,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		1 year 4 months 24 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value		$ 6,000,000.0