Note 6 - Stock-based Compensation - Options/SARs Activity (Details) - Options/SARs [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Outstanding (in shares)		2,533	3,024	2,793
Outstanding, weighted average exercise price (in dollars per share)		$ 20.81	$ 17.78	$ 15.51
Granted (in shares)			380	380
Granted, weighted average exercise price (in dollars per share)			$ 53.50	$ 31.65
Exercised (in shares)		(1,184)	(390)	(139)
Exercised, weighted average exercise price (in dollars per share)		$ 16.19	$ 9.43	$ 10.52
Expired (in shares)			(5)	(10)
Expired, weighted average exercise price (in dollars per share)			$ 9.17	$ 9.74
Forfeited (in shares)			(476)
Forfeited, weighted average exercise price (in dollars per share)			$ 37.14
Outstanding (in shares)		1,349	2,533	3,024
Outstanding, weighted average exercise price (in dollars per share)		$ 24.86	$ 20.81	$ 17.78
Outstanding, weighted average remaining contractual term (Year)		3 years 109 days
Outstanding, aggregate intrinsic value		$ 34,018
Vested and exercisable (in shares)	[1]	1,064
Vested and exercisable, weighted average exercise price (in dollars per share)		$ 20.70
Vested and exercisable, weighted average remaining contractual term (Year)		2 years 255 days
Vested and exercisable, aggregate intrinsic value		$ 30,691

[1] The number of SARs vested and exercisable at January 31, 2019 includes 877,500 Class A and 127,500 Class B shares previously held by Mr. Karl Lopker which will expire on August 25, 2019 if not exercised by his estate. Exercise prices for these SARs range from $10.50 to $31.65.