Note 5 - Stock-based Compensation - Options/SARs Activity (Details) - Options/SARs [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Outstanding (in shares)	2,793	2,596	2,499
Outstanding, weighted average exercise price (in dollars per share)	$ 15.51	$ 14.74	$ 12.69
Granted (in shares)	380	380	380
Granted, weighted average exercise price (in dollars per share)	$ 31.65	$ 18.64	$ 25.34
Exercised (in shares)	(139)	(158)	(266)
Exercised, weighted average exercise price (in dollars per share)	$ 10.52	$ 10.94	$ 10.69
Expired (in shares)	(10)	(17)	(12)
Expired, weighted average exercise price (in dollars per share)	$ 9.74	$ 12.56	$ 14.22
Forfeited (in shares)		(8)	(5)
Forfeited, weighted average exercise price (in dollars per share)		$ 12.09	$ 12.05
Outstanding (in shares)	3,024	2,793	2,596
Outstanding, weighted average exercise price (in dollars per share)	$ 17.78	$ 15.51	$ 14.74
Outstanding, weighted average remaining contractual term (Year)	4 years
Outstanding, aggregate intrinsic value	$ 72,901
Vested and exercisable (in shares)	2,073
Vested and exercisable, weighted average exercise price (in dollars per share)	$ 14.25
Vested and exercisable, weighted average remaining contractual term (Year)	2 years 328 days
Vested and exercisable, aggregate intrinsic value	$ 57,045