Share-Based Compensation (Options Granted Under Stock Option Plans) (Details) shares in Thousands	9 Months Ended
	Oct. 31, 2020 $ / shares shares
Number of Shares
Options outstanding at beginning of year	2,881
Granted	1,069
Exercised	(10)
Expired or cancelled	(235)
Options outstanding at end of period	3,705
Options exercisable at end of period	2,560
Options available for future grant at end of period	6,171
Weighted-Average Exercise Price
Options outstanding at beginning of year | $ / shares	$ 54.21
Granted | $ / shares	21.61
Exercised | $ / shares	17.44
Expired or cancelled | $ / shares	34.34
Options outstanding at end of period | $ / shares	46.16
Options exercisable at end of period | $ / shares	$ 53.90
Options outstanding, weighted-average remaining contractual life	5 years 8 months 12 days
Options exercisable at end of period, Weighted-average remaining contractual life	4 years 2 months 12 days