Note 11 - Stock-based Compensation - Options/SARs Activity (Details) - Options/SARs [Member] $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jul. 31, 2018 USD ($) $ / shares shares
Outstanding (in shares) | shares	3,024
Outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 17.78
Granted (in shares) | shares	380
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 53.50
Exercised (in shares) | shares	(384)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 9.39
Expired (in shares) | shares	(5)
Expired, weighted average exercise price (in dollars per share) | $ / shares	$ 8.97
Forfeited (in shares) | shares	(1)
Forfeited, weighted average exercise price (in dollars per share) | $ / shares	$ 19.40
Outstanding (in shares) | shares	3,014
Outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 23.37
Outstanding at July 31, 2018 (Year)	4 years 182 days
Outstanding at July 31, 2018 | $	$ 77,830
Vested and exercisable (in shares) | shares	2,064
Vested and exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 17.02
Vested and exercisable, weighted average remaining contractual term (Year)	3 years 146 days
Vested and exercisable, aggregate intrinsic value | $	$ 64,899