Derivative Instruments (Narrative) (Details) (USD $)	3 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net foreign currency exchange loss	$ (8,800,000)	$ 16,900,000
Notional amount of derivative financial instruments outstanding	$ 800,000,000	$ 2,100,000,000
Average maturities of derivatives, days	34 days	28 days