Fair Value Measurements (Details) (USD $)	12 Months Ended									12 Months Ended
	Jan. 31, 2014	Jan. 31, 2014 Senior Notes	Jan. 31, 2013 Senior Notes	Sep. 30, 2012 Senior Notes	Jan. 31, 2014 Level 1 Senior Notes	Jan. 31, 2014 Level 2 Fair Value, Measurements, Recurring	Jan. 31, 2013 Level 2 Fair Value, Measurements, Recurring	Jan. 31, 2014 Level 3 Fair Value, Measurements, Recurring	Jan. 31, 2013 Level 3 Fair Value, Measurements, Recurring	Jan. 31, 2014 Selling, General and Administrative Expenses	Jan. 31, 2014 Other Expense (Income)
Assets, Fair Value Disclosure [Abstract]
Foreign currency forward contracts						$ 6,160,000	$ 19,835,000
Liabilities, Fair Value Disclosure [Abstract]
Foreign currency forward contracts						2,423,000	19,628,000
Business Combination, Contingent Consideration, Liability								10,571,000	18,147,000
Adjustments to the fair value of acquisition-related contingent consideration										800,000	500,000
Acquisition related contingent consideration paid	8,700,000
Fair value of deferred compensation plan assets	38,400,000
Fair value of deferred compensation plan liabilities	33,800,000
Convertible senior debentures, face value		350,000,000	350,000,000	350,000,000
Convertible debt, fair value disclosures					$ 364,200,000