Derivative Instruments (Narrative) (Details) (USD $)	12 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net foreign currency exchange loss	$ (18,800,000)	$ (17,200,000)	$ 13,100,000
Notional amount of derivative financial instruments outstanding	$ 700,000,000	$ 1,600,000,000
Average maturities of derivatives, days	32 days	28 days