Note 6 - Stock-based Compensation - RSUs Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares shares in Thousands		12 Months Ended
		Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Restricted stock (in shares)		627	663	653
Restricted stock, weighted average grant date fair value (in dollars per share)		$ 39.86	$ 36.64	$ 25.10
Granted (in shares)		350	281	300
Granted, weighted average grant date fair value (in dollars per share)		$ 40.50	$ 40.43	$ 51.70
Released (in shares)	[1]	(258)	(267)	(263)
Released, weighted average grant date fair value (in dollars per share)	[1]	$ 35.99	$ 32.71	$ 25.80
Forfeited (in shares)		(21)	(50)	(27)
Forfeited, weighted average grant date fair value (in dollars per share)		$ 41.67	$ 38.51	$ 30.63
Restricted stock (in shares)		698	627	663
Restricted stock, weighted average grant date fair value (in dollars per share)		$ 41.56	$ 39.86	$ 36.64

[1] The number of RSUs released includes shares withheld on behalf of employees to satisfy minimum statutory tax withholding requirements. During the fiscal years ended January 31, 2021, 2020 and 2019, the Company withheld 80,000 shares, 82,000 shares and 81,000 shares, respectively, for payment of these taxes. The value of the withheld shares for the fiscal years ended January 31, 2021, 2020 and 2019 were $3.4 million, $3.5 million and $4.3 million, respectively.