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, 2019	Jan. 31, 2018	Jan. 31, 2017
Outstanding (in shares)		3,024	2,793	2,596
Outstanding, weighted average exercise price (in dollars per share)		$ 17.78	$ 15.51	$ 14.74
Granted (in shares)		380	380	380
Granted, weighted average exercise price (in dollars per share)		$ 53.50	$ 31.65	$ 18.64
Exercised (in shares)		(390)	(139)	(158)
Exercised, weighted average exercise price (in dollars per share)		$ 9.43	$ 10.52	$ 10.94
Expired (in shares)		(5)	(10)	(17)
Expired, weighted average exercise price (in dollars per share)		$ 9.17	$ 9.74	$ 12.56
Forfeited (in shares)		(476)		(8)
Forfeited, weighted average exercise price (in dollars per share)		$ 37.14		$ 12.09
Outstanding (in shares)		2,533	3,024	2,793
Outstanding, weighted average exercise price (in dollars per share)		$ 20.81	$ 17.78	$ 15.51
Outstanding, weighted average remaining contractual term (Year)		3 years 182 days
Outstanding, aggregate intrinsic value		$ 53,155
Vested and exercisable (in shares)	[1]	2,058
Vested and exercisable, weighted average exercise price (in dollars per share)		$ 17.04
Vested and exercisable, weighted average remaining contractual term (Year)		2 years 328 days
Vested and exercisable, aggregate intrinsic value		$ 48,873

[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.