Fair Value Of Financial Instruments (Details) (USD $)	6 Months Ended
	Jul. 31, 2014	Jul. 31, 2014 Senior Notes	Jan. 31, 2014 Senior Notes	Sep. 30, 2012 Senior Notes	Jul. 31, 2014 Level 1 Senior Notes	Jul. 31, 2014 Level 2 Fair Value, Measurements, Recurring	Jan. 31, 2014 Level 2 Fair Value, Measurements, Recurring	Jul. 31, 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						$ 2,960,000	$ 6,160,000
Foreign currency forward contracts, Liabilities						2,002,000	2,423,000
Deferred compensation plan assets, fair value disclosure	40,200,000
Deferred compensation liability, fair value disclosure	36,000,000
Convertible senior debentures, face value		350,000,000	350,000,000	350,000,000
Convertible debt, fair value disclosures					365,900,000
Payments for Previous Acquisition	7,000,000
Business Combination, Contingent Consideration, Liability								$ 3,799,000	$ 10,571,000