Fair Value Of Financial Instruments (Details) (USD $)	3 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014 Senior Notes	Jan. 31, 2014 Senior Notes	Sep. 30, 2012 Senior Notes	Apr. 30, 2014 Fair Value, Measurements, Recurring	Apr. 30, 2014 Level 1 Senior Notes	Apr. 30, 2014 Level 2 Fair Value, Measurements, Recurring	Jan. 31, 2014 Level 2 Fair Value, Measurements, Recurring	Apr. 30, 2014 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring	Jan. 31, 2014 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts, Assets								$ 2,024,000	$ 6,160,000
Foreign currency forward contracts, Liabilities								2,408,000	2,423,000
Business Combination, Contingent Consideration, Liability										6,790,000	10,571,000
Payments for Previous Acquisition	4,200,000	6,183,000
Deferred compensation plan assets, fair value disclosure						39,400,000
Deferred compensation liability, fair value disclosure						34,900,000
Convertible senior debentures, face value			350,000,000	350,000,000	350,000,000
Convertible debt, fair value disclosures							$ 368,000,000