Derivative Instruments (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net foreign currency exchange (gain) loss	$ 7,600,000	$ (6,900,000)	$ 2,100,000	$ 13,600,000
Notional amount of derivative financial instruments outstanding	$ 600,000,000	$ 1,400,000,000
Average maturities of derivatives, days	35 days	30 days