Note 11 - Stock-based Compensation (Details Textual) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2020 USD ($) shares	Jul. 31, 2020 USD ($) shares
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares	74,000	76,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 3.1	$ 3.2
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 27.8	$ 27.8
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		3 years
Performance Shares [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares	8,000	8,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 0.3	$ 0.3
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 3.4	$ 3.4
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		1 year 4 months 24 days
Stock Appreciation Rights (SARs) [Member]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares) | shares	56,000	57,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 2.4	$ 2.4
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 1.9	$ 1.9
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		1 year 8 months 12 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value		$ 6.0