Retirement Benefit Plans - Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning projected benefit obligation	$ 145.2	$ 144.7
Service cost	5.6	5.7	$ 4.6
Interest cost	3.0	3.3	3.9
Actuarial loss (gain)	7.1	6.3
Benefits paid	(2.6)	(6.5)
Foreign currency exchange rate changes	(9.5)	(10.1)
Curtailments and settlements	(6.8)	(2.2)
Contributions by plan participants	4.4	4.0
Ending projected benefit obligation	146.4	145.2	144.7
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning fair value of plan assets	101.4	104.2
Actual return on plan assets	4.2	1.3
Contributions paid by employer	15.3	4.5
Contributions paid by plan participants	4.4	4.0
Benefit payments	(2.6)	(6.5)
Curtailments and settlements	(6.8)	0.0
Foreign currency exchange rate changes	(8.5)	(6.1)
Ending fair value of plan assets	107.4	101.4	$ 104.2
Funded status	$ (39.0)	$ (43.8)