Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net foreign currency exchange gain (loss)	$ (1.2)	$ 4.9	$ (2.0)	$ 2.9
Notional amount of derivative financial instruments outstanding	$ 700.0	$ 500.0	$ 600.0	$ 500.0
Average maturities of derivatives, days	33 days	24 days	32 days	31 days