Share-Based Compensation (Options Granted Under Stock Option Plans) (Details) shares in Thousands	3 Months Ended
	Apr. 30, 2016 $ / shares shares
Number of Shares
Options outstanding at beginning of year	3,694
Granted	465
Exercised	(324)
Expired or cancelled	(18)
Options outstanding at end of period	3,817
Options exercisable at end of period	2,713
Options vested and expected to vest at end of period	3,767
Options available for future grant at end of period	12,050
Weighted-Average Exercise Price
Options outstanding at beginning of year | $ / shares	$ 32.62
Granted | $ / shares	63.79
Exercised | $ / shares	22.16
Expired or cancelled | $ / shares	52.96
Options outstanding at end of period | $ / shares	37.21
Options exercisable at end of period | $ / shares	27.86
Options vested and expected to vest at end of period | $ / shares	$ 36.89
Options outstanding, Weighted-average Remaining Contractual Life	5 years 10 months 24 days
Options exercisable at end of period, Weighted-average remaining contractual life	4 years 7 months 6 days
Options vested and expected to vest, Weighted-average remaining contractual life	5 years 10 months 24 days