Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net foreign currency exchange gain (loss)	$ (7.4)	$ (8.0)
Notional amount of derivative financial instruments outstanding	$ 500.0	$ 500.0
Average maturities of derivatives, days	30 days	37 days