Note 12 - Stock-based Compensation (Details Textual) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2021 USD ($) shares	Jul. 31, 2021 USD ($) shares
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares	80,000	83,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 6.2	$ 6.4
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 23.6	$ 23.6
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		2 years 7 months 6 days
Performance Shares [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares	23,000	23,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 1.8	$ 1.8
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 4.4	$ 4.4
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		1 year 3 months 18 days
Stock Appreciation Rights (SARs) [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares	69,000	69,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 5.1	$ 5.1
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 0.7	$ 0.7
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		10 months 24 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value		$ 11.8